NCHurricane2009's Blog

2016 Atlantic Hurricane Season Birdseye Discussion #157

By: NCHurricane2009, 5:49 AM GMT on October 31, 2016

...MONDAY OCTOBER 31 2016 1:49 AM EDT...
The following statement concerns area of interest #1 marked over the western Caribbean Sea in the atmospheric features chart below. The surface low in the region has begun to fire thunderstorm activity over and west of its center as the vertical shear favorably reduces due to the upper vortex in the western Gulf of Mexico weakening into an upper trough moving westward and away into Mexico. Will continue to monitor this surface low as the shear will remain favorably low for a few more days.

The following statement concerns area of interest #2 marked over the western Atlantic to the north of Puerto Rico and Lesser Antilles. The surface low in this area will become enhanced by a southern fracture of the shortwave upper trough currently entering the Atlantic from eastern North America. This fracture is expected to evolve into a cut-off upper vortex such that the surface low could evolve into a subtropical disturbance while it moves northeastward into the central Atlantic. Therefore will also watch this area over the next days.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0128Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

2016 Atlantic Hurricane Season Birdseye Discussion #156

By: NCHurricane2009, 5:20 AM GMT on October 30, 2016

...SUNDAY OCTOBER 30 2016 1:20 AM EDT...
The following statement concerns area of interest #1 marked over the western Caribbean Sea in the atmospheric features chart below. The surface low in the region is not showing signs of development despite the shearing upper vortex in the western Gulf of Mexico beginning to shift westward and away. However will continue to monitor this surface low as the shear will remain favorably low for a period of time.

The following statement concerns area of interest #2 marked over the western Atlantic to the north of Puerto Rico and Lesser Antilles. The decaying surface cold front in this region has evolved into a surface trough with 1012 mb surface low. It is likely this surface low will become enhanced by a southern fracture of the shortwave upper trough currently over the central United States. This fracture is expected to evolve into a cut-off upper vortex such that the surface low could evolve into a subtropical disturbance. Therefore will also watch this area over the next days.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1928Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

2016 Atlantic Hurricane Season Birdseye Discussion #155

By: NCHurricane2009, 6:54 AM GMT on October 29, 2016

...SATURDAY OCTOBER 29 2016 2:55 AM EDT...
The following statement concerns area of interest #1 marked over the western Caribbean Sea in the atmospheric features chart below. A 1008 mb surface low in the western Caribbean Sea persists while remaining supported by upper divergence on the east side of an upper vortex that is currently over the western Gulf of Mexico. The upper vortex is also shearing all shower and thunderstorm activity northward from the surface low. However due to a strong upper ridge over the western United States...the upper vortex is expected to shift westward and away which will favorably reduce the shear over this disturbance. Therefore will continue to monitor this disturbance.

The following statement concerns area of interest #2 marked over the western Atlantic to the north of Puerto Rico and Lesser Antilles. A decaying surface cold front in this region will likely become enhanced by a southern fracture of a shortwave upper trough to eject from the United States. Some of the latest model runs suggest this fracture could evolve into a cut-off upper vortex located far south enough over warm water to enhance the decaying front into a subtropical disturbance. Therefore will also watch this area over the next days...especially if more models agree with this solution.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0130Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

2016 Atlantic Hurricane Season Birdseye Discussion #154

By: NCHurricane2009, 6:34 AM GMT on October 28, 2016

...FRIDAY OCTOBER 28 2016 2:35 AM EDT...
The following statement concerns area of interest #1 marked over the western Caribbean Sea...eastern Gulf of Mexico...and western Bahamas in the atmospheric features chart below. A 1009 mb surface low in the western Caribbean Sea has developed from the remnants of a surface front while supported by upper divergence on the east side of an upper vortex that is currently over the western Gulf of Mexico. The upper vortex is also shearing all shower and thunderstorm activity northward from the surface low and into the eastern Gulf of Mexico and western Bahamas. However due to a strong upper ridge moving into the western United States...the upper vortex is expected to shift westward and away which will favorably reduce the shear over this disturbance. Therefore will continue to monitor this disturbance.

The following statement concerns area of interest #2 marked over the western Atlantic to the east of the Bahamas and north of Puerto Rico. The decaying surface cold front mentioned in area of interest #1 extends through this region and will likely become enhanced by a southern fracture of the upper trough currently over the northeastern United States and southern fracture of another shortwave upper trough to follow behind. Some of the latest model runs suggest these fractures could evolve into a cut-off upper vortex located far south enough over warm water to enhance the decaying front in this area into a subtropical disturbance. Therefore will also watch this area over the next days...especially if more models agree with this solution.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1933Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

2016 Atlantic Hurricane Season Birdseye Discussion #153

By: NCHurricane2009, 6:24 AM GMT on October 27, 2016

...THURSDAY OCTOBER 27 2016 2:24 AM EDT...
The following statement concerns area of interest #1 marked over the central tropical Atlantic in the atmospheric features chart below. The thunderstorm activity in this area once induced by divergence on the perimeter of a cut-off upper vortex has diminished. Therefore this is my final statement on this disturbance on this blog.

The following statement concerns area of interest #2 marked over the western Caribbean Sea in the atmospheric features chart below. The tail end of a surface cold front in the area has decayed into a surface trough...with the shower and thunderstorm activity more widespread and stronger since the previous blog update due to supportive upper divergence on the east side of an upper trough that is currently over the western Gulf of Mexico. Due to a strong upper ridge moving into the western United States...the upper trough is expected to evolve into a cut-off upper vortex that moves westward and away which will favorably reduce the shear over this disturbance. The shear is also likely to reduce as the upper ridging currently over the Caribbean will continue to expand northward due to warm air advection ahead of the 1015 mb frontal cyclone moving into the northeastern United States. Therefore will continue to monitor this disturbance.

The following statement concerns area of interest #3 marked over the western Atlantic to the north of the Lesser Antilles and Puerto Rico in the atmospheric features chart below. The decaying surface cold front mentioned in area of interest #2 extends through this region and will likely become enhanced by a southern fracture of the upper trough currently moving into the northeastern United States. Some of the latest model runs suggest this fracture could evolve into a cut-off upper vortex located far south enough over warm water to enhance the decaying front in this area into a subtropical disturbance. Therefore will also watch this area over the next days...especially if more models agree with this solution.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0127Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

2016 Atlantic Hurricane Season Birdseye Discussion #152

By: NCHurricane2009, 6:50 AM GMT on October 25, 2016

...TUESDAY OCTOBER 25 2016 2:51 AM EDT...
The following statement concerns area of interest #1 marked over the central tropical Atlantic in the atmospheric features chart below. The thunderstorm activity in this area persists while remaining supported by divergence on the east side of a cut-off upper vortex. By 72 hours the upper ridging currently over the Caribbean is expected to expand northeastward into the Atlantic due to warm air advection ahead of a frontal cyclone expected to move into the northeastern United States...which will push the cut-off upper vortex southward while the expanding upper ridging possibly provides a more favorable atmospheric environment for these thunderstorms to develop. Therefore will continue to monitor this area of disturbed weather.

The following statement concerns area of interest #2 marked over the western Caribbean Sea in the atmospheric features chart below. The tail end of a surface cold front in the area is beginning to become enhanced by the east side of a shortwave upper trough nearing from the Gulf of Mexico and southeastern United States. The upper trough is then expected to evolve into a cut-off upper vortex that moves westward and away which will favorably reduce the shear...due to a strong upper ridge expected to move into the western United States. The shear is also likely to reduce by 72 hours as the upper ridging currently over the Caribbean is expected to expand northward due to warm air advection ahead of a frontal cyclone expected to move into the northeastern United States. Therefore will also be watching the western Caribbean sea for the development of a tropical disturbance over the next few days.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0117Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

2016 Atlantic Hurricane Season Birdseye Discussion #151

By: NCHurricane2009, 8:36 AM GMT on October 24, 2016

...MONDAY OCTOBER 24 2016 4:36 AM EDT...
The following statement concerns area of interest #1 marked over the northwestern Atlantic in the atmospheric features chart below. The broad surface low that was northeast of the Bahamas has become drawn northward and become absorbed by a frontal system moving offshore from the United States since the previous blog update. Therefore this is my final statement on this blog concerning this system.

The following statement concerns area of interest #2 marked over the central tropical Atlantic in the atmospheric features chart below. The vigorous tropical wave that was in the eastern tropical Atlantic has shifted into the central tropical Atlantic since the previous blog update. The tropical wave is currently inactive while approaching the Lesser Antilles...but the thunderstorm activity that was once associated with the tropical wave persists while supported by divergence on the east side of a cut-off upper vortex that has developed in the central Atlantic. By 96 hours the upper ridging currently over the Caribbean is expected to expand northeastward into the Atlantic due to warm air advection ahead of a frontal cyclone expected to move into the northeastern United States...which will push the cut-off upper vortex southward while the expanding upper ridging possibly provides a more favorable atmospheric environment for these thunderstorms to develop. Therefore will continue to monitor this area of disturbed weather.

The following statement concerns area of interest #3 marked over the western Caribbean Sea in the atmospheric features chart below. The tail end of a surface cold front in the area may become enhanced by divergence on the east side of a shortwave upper trough currently over Mexico and Texas as the upper trough nears. The upper trough is then expected to evolve into a cut-off upper vortex that moves westward and away which will favorably reduce the shear...due to a strong upper ridge expected to move into the western United States. The shear is also likely to reduce by 96 hours as the upper ridging currently over the Caribbean is expected to expand northward due to warm air advection ahead of a frontal cyclone expected to move into the northeastern United States. Therefore will also be watching the western Caribbean sea for the development of a tropical disturbance over the next few days.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0116Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

2016 Atlantic Hurricane Season Birdseye Discussion #150

By: NCHurricane2009, 6:07 AM GMT on October 20, 2016

**I will continue to be on vacation through the 23rd of October. Therefore my blog updates on the Atlantic tropics will likely be limited in the next days. Visit www.nhc.noaa.gov...www.wunderground.com/hurricane. ..or other sources on the Atlantic tropics for up to the minute latest information**

...THURSDAY OCTOBER 20 2016 2:15 AM EDT...
The following statement concerns area of interest #1 marked in the atmospheric features chart. Since the previous blog post...Nicole has transitioned into a non-tropical remnant gale currently located on the east coast of Greenland. Therefore this is my final statement on Nicole on this blog.

The following statement concerns area of interest #2 marked over the western Atlantic to the northeast of the Bahamas. The cut-off upper trough in the region has amplified further into a cut-off upper vortex...with divergence on the east side of the upper vortex continuing to support a broad surface low. There are no signs of a consolidating circulation developing and this system only has 48 hours to further develop before becoming absorbed by the frontal system currently over the central US. Therefore it is becoming less likely that a tropical or subtropical cyclone will form from this system...and I have cancelled it as a special feature on this blog.

The following statement concerns area of interest #3 marked over the eastern tropical Atlantic in the atmospheric features chart below. The tropical wave in the region is producing a larger and stronger area of showers and thunderstorms while taking advantage of a low shear and good upper outflow environment beneath favorable upper ridge. However this activity is not currently organized...but the CMC...NAVGEM...and GFS models suggest some additional development may be possible with this system. Therefore will continue to watch this area over the next couple of days as well.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 0127Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

2016 Atlantic Hurricane Season Birdseye Discussion #149

By: NCHurricane2009, 8:28 AM GMT on October 18, 2016

**I will continue to be on vacation through the 23rd of October. Therefore my blog updates on the Atlantic tropics will likely be limited in the next days. Visit www.nhc.noaa.gov...www.wunderground.com/hurricane. ..or other sources on the Atlantic tropics for up to the minute latest information**

...TUESDAY OCTOBER 18 2016 4:30 AM EDT...
Nicole weakens to a tropical storm in the north-central Atlantic...but significant waves and wind in the north Atlantic affecting shipping interests are expected during the next day or so. See the first special feature section for more details. Visit www.nhc.noaa.gov for up to the minute latest information on Nicole.

The following statement concerns area of interest #1 marked over the western Atlantic to the northeast of the Bahamas. The amplified cut-off upper trough in the region continues to support a developing disturbance and computer models continue to agree that a subtropical or tropical cyclone is likely to form in the next few days. However this system is likely to stay away from land areas and become absorbed by a cold front emerging from North America in about 4 days. I was not able to post a special update yesterday with a tropical cyclone formation forecast due to circumstances on my vacation...but have now finally been able to produce a speical feature section for this system with this update. See the second special feature section below for additional details.

The following statement concerns area of interest #2 marked over the eastern tropical Atlantic in the atmospheric features chart below. A tropical wave in the region has not become any better organized despite favorable upper ridging (with low shear and good upper outflow) shifting overhead. However the CMC and NAVGEM computer models continue to suggest that tropical development may occurr and therefore will continue to watch this area over the next couple of days as well.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0131Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...TROPICAL STORM NICOLE...
Current Prognosis...Nicole's thunderstorm activity is becoming weaker while rapdily accelerating northward into cooler waters...and more asymmetric in distribution due to increasing southwesterly vertical shear. As a result Nicole has weakened to a tropiacl storm. As of 0000Z earlier this evening the center of Nicole was located at 43.5N-41.5W.

Atmospheric Outlook for the Forecast Period...Nicole is accelerating northward as the 1001 mb frontal cyclone that is emerging from the east coast of Canada approaches from the west. Southwesterly vertical shear over the tropical storm is increasing as the overhead upper vortex has opened into an upper trough while merging with the upper trough associated with the incoming frontal cyclone. The shear should strip away Nicole's thunderstorms from its center which should help in the transition to non-tropical in the next 24 hours.

Thermodynamic Outlook for the Forecast Period...As Nicole accelerates northward toward even cooler water temps in the teens of deg C in the next 24 hours...transition to non-tropical is expected.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 19)...Strong non-tropical remnant gale centered at 55N-38W

Track Forecast...Although Nicole is only slightly east of my previous forecast track based on the 0000Z center fix in the above current prognosis...I have also shifted the forecast slightly northward to keep up with the latest computer model guidance that shows a faster northward acceleration.

Intensity Forecast...Nicole is likely to maintain its current tropical storm force strength for the next day or so while receiving supportive upper divergence when from the east side of the upper trough associated with the eastern Canada 1001 mb frontal cyclone.

Impact Forecast...The impact swath in the above forecast graphic is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track. Due to the large field of winds and waves...the north Atlantic will be treacherous for shipping interests in the next day or so.

...SPECIAL FEATURE...SURFACE LOW INVEST 99-L...
This special feature section is for area of interest #1 marked in the above atmospheric features chart.

Current Prognosis...The cut-off upper trough over the Gulf of Mexico and western Atlantic remains amplified in nature...in response to amplifying upper ridging propped up by warm air advection ahead of the surface frontal system currently over central North America. Divergence on the east side of the amplified upper trough is supporting shower and thunderstorm activity as well as a new surface low currently located just northeast of the eastern Bahamas. Although the thunderstorm activity has become concentrated...the circulation of the surface low is not well-defined in satellite animation but is analyzed by the NHC TAFB to be located at 24N-72.5W.

Atmospheric Outlook for the Forecast Period...For the first part of the forecast period...the surface low will be trapped south of the 1018 mb ridge which has emerged from the east coast of the US...and thus its motion for the next 48 hours will largely depend on the location of the upper divergence maximum on the east side of the cut-off upper trough...which will shift northeast and then back to the west as the upper trough amplifies further into a cut-off upper vortex. Beyond 48 hours...a large upper trough moving into central North America will produce a vigorous surface frontal cyclone...with both features quickly shifting offshore. The large upper trough is expected to absorb the cut-off upper vortex and begin to shear this system...so any tropical cyclone that develops will likely have thunderstorm activity lopsided to the east half of the circulation. Meanwhile the surface frontal cyclone will draw this system northward and absorb it perhaps by 96 hours based on the latest model runs.

Thermodynamic Outlook for the Forecast Period...Based on the latest forecast track...this system will be over 30 to 27 deg C waters warm enough to support tropical development.

24 Hr Forecast (0000Z Oct 19)...Surface low centered at 25N-66W

48 Hr Forecast (0000Z Oct 20)...Surface low centered at 26N-70W

72 Hr Forecast (0000Z Oct 21)...45 mph maximum sustained wind tropical storm centered at 27.5N-70W

96 Hr Forecast (0000Z Oct 22)...Remnant frontal low centered between Bermuda and the Carolinas at 32.5N-70W

2016 Atlantic Hurricane Season Birdseye Discussion #148

By: NCHurricane2009, 6:25 AM GMT on October 17, 2016

**I will continue to be on vacation through the 23rd of October. Therefore my blog updates on the Atlantic tropics will likely be limited in the next days. Visit www.nhc.noaa.gov...www.wunderground.com/hurricane. ..or other sources on the Atlantic tropics for up to the minute latest information**

...MONDAY OCTOBER 17 2016 2:30 AM EDT...
Nicole remains a large sized hurricane in the north-central Atlantic...significant waves and wind in the north Atlantic affecting shipping interests to continue for a few more days. See the special feature section for more details. Visit www.nhc.noaa.gov for up to the minute latest information on Nicole.

The following statement concerns area of interest #1 marked over the northern Caribbean...Bahamas...and western Atlantic in the atmoshperic features chart below. The cut-off upper trough over the southeastern United States remains amplified in nature while moving into the Gulf of Mexico and western Atlantic...in response to amplifying upper ridging now becoming propped up by warm air advection ahead of the frontal cyclone currently over northwestern North America. Divergence on the east side of the amplified upper trough is supporting shower and thunderstorm activity as well as a surface trough over the northern Caribbean Islands...eastern Bahamas...and western Atlantic. Computer models are increasingly agreeing that the amplified upper trough will become a cut-off upper vortex that supports a subtropical or tropical disturbance in the western Atlantic just north of the Caribbean and Bahamas. Therefore I will be upgrading this system to a special feature with a tropical cyclone formation forecast in a special update later on (currently unable to do so due to vacation plans).

The following statement concerns area of interest #2 marked over the eastern tropical Atlantic in the atmospheric features chart below. A tropical wave which has recently emerged from Africa has become organized into a 1012 mb surface low. The favorable upper ridging currently in the eastern Atlantic (marked by a blue H in the bottom-right of the atmospheric features chart below) is forecast to shift eastward toward the tropical wave while the upper trough currently over Hurricane Nicole also shifts east. The CMC and NAVGEM computer models suggest that some tropical development may occurr as the tropical wave takes advantage of low shear and upper outflow beneath the upper ridging. Therefore will continue to watch this area over the next couple of days as well.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0139Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...HURRICANE NICOLE...
Current Prognosis...Nicole remains a hurricane with a large eye surrounded by a ring of thunderstorms. The thunderstorm activity continues to be supported by the cold temperatures of the overhead upper vortex despite the hurricane being over waters below 26 deg C. With the cold core upper vortex helping this system...perhaps Nicole could be considered a subtropical storm but at hurricane force. As of 0000Z earlier this evening the center of Nicole was located at 40.2N-45.8W.

Atmospheric Outlook for the Forecast Period...Nicole is beginning to accelerate northeastward as the 997 mb frontal cyclone emerging from eastern Canada approaches from the northwest. Nicole is currently in an oasis of low vertical shear beneath the upper vortex mentioned in the above current prognoisis...but the shear should once again increase once the upper vortex opens into an upper trough while merging with the upper trough associated with the incoming frontal cyclone. The shear should strip away Nicole's thunderstorms from its center which should help in the transition to non-tropical at the end of the forecast period.

Thermodynamic Outlook for the Forecast Period...Nicole is currently a hurricane despite being over water temps below 26 deg C...due to the dynamics explained in the above current prognosis section. However once Nicole accelerates northeastward toward water temps in the teens to low 20s in 48 hours...transition to non-tropical is likely.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 18)...80 mph maximum sustained wind hurricane centered at 43.2N-42.5W

48 Hr Forecast (0000Z Oct 19)...Strong non-tropical remnant gale centered at 54N-39W

Track Forecast...Nicole is currently northeast of my previous forecast track based on the above 0000Z center fix. However Nicole also appears to be hooking more sharply northward in the latest satellite loop which may help it re-align with the previous forecast track as far as the east-to-west alignment. Therefore I have only adjusted my track forecast points northward.

Intensity Forecast...Nicole is likely to maintain its current hurricane-force strength for at least the next 48 hours as it will again receive supportive upper divergence when the east side of the upper trough associated with the eastern Canada 997 mb frontal cyclone arrives. I have delayed the transition to non-tropical to 0000Z October 19 as Nicole's current levels of thunderstorm activity suggests transition to non-tropical is not as likely in the next 24 hours.

Impact Forecast...The impact swath in the above forecast graphic is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track. Due to the large field of winds and waves...the north Atlantic will be treacherous for shipping interests in the next few days.

2016 Atlantic Hurricane Season Birdseye Discussion #147

By: NCHurricane2009, 5:43 AM GMT on October 16, 2016

**I will continue to be on vacation through the 23rd of October. Therefore my blog updates on the Atlantic tropics will likely be limited in the next days. Visit www.nhc.noaa.gov...www.wunderground.com/hurricane. ..or other sources on the Atlantic tropics for up to the minute latest information**

...SUNDAY OCTOBER 16 2016 1:40 AM EDT...
Nicole becomes a large sized hurricane while moving into the north-central Atlantic...significant waves and wind in the north Atlantic affecting shipping interests to continue for a few more days. See the special feature section for more details. Visit www.nhc.noaa.gov for up to the minute latest information on Nicole.

The following statement concerns area of interest #1 marked over the souhtwestern Gulf of Mexico and southwestern Caribbean Sea in the atmospheric features chart below. A portion of the upper troughing over eastern North America has become cut-off and amplified over the southeastern United States...in response to an amplifying upper ridge propped up by the 992 mb frontal cyclone currently over eastern Canada. Divergence on the east side of the amplifying upper trough has supported the formation of a 1014 mb surface low in the southwestern Gulf of Mexico...and a tropical wave passing through the Caribbean has transitioned into a surface 1009 mb low and surface trough supportive by the outflow of an upper ridge that has developed in relativel higher pressures ahead of the amplifying upper trough. It is possible that as the amplifying upper trough moves into the western Atlantic...it could become a cut-off upper vortex that supports a subtropical disturbance just north of the Caribbean...or a tropical disturbance could develop in the Caribbean under the support of the aforemtioned upper ridge.

The following statement concerns area of interest #2 marked over the eastern tropical Atlantic in the atmospheric features chart below. Satellite imagery suggests a strong tropical wave has recently emerged from western Africa. The favorable upper ridging currently in the central Atlantic (marked by a blue H in the bottom-center of the atmospheric features chart below) is forecast to shift eastward toward the tropical wave while the upper trough currently over Hurricane Nicole also shifts east. The CMC and NAVGEM computer models suggest that some tropical development may occurr as the tropical wave takes advantage of low shear and upper outflow beneath the upper ridging. Therefore will continue to watch this area over the next couple of days as well.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1918Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...HURRICANE NICOLE...
Current Prognosis...What a surprise to find Nicole is still hanging around with tropical characteristics while on vacation. While supported by divergence on the east side of the upper trough that has emerged from North America...Nicole has retained category 1 hurricane force. The strong winds on Nicole's west side have pulled cold air beneath the upper trough southward...resulting in a small cold core upper vortex that is becoming stacked with the hurricane. The temperatures of this upper vortex are cold enough to support thunderstorm activity around Nicole's center despite the hurricane crossing the 26 deg C isotherm into cooler waters...enough for the National Hurricane Center to still classify Nicole as a tropical system. With the cold core upper vortex helping to maintain the thunderstorm activity...perhaps Nicole could be considered a subtropical storm but at hurricane force. As of 0000Z earlier this evening the center of Nicole was located at 39.5N-48.5W.

Atmospheric Outlook for the Forecast Period...Nicole has essentially stalled while entering the north-central Atlantic...trapped between a 1018 mb surface ridge to the northeast and 1031 mb surface ridge over the east coast of North America. Through the forecast period...the 992 mb frontal cyclone over eastern Canada will approach from the northwest and create enough of a gap betwen both ridges to begin steering the hurricane. The flow around the southeast side of the frontal cyclone will swing Nicole eastward and then northward. Nicole is currently in an oasis of low vertical shear beneath the upper vortex mentioned in the above current prognoisis...but the shear should once again increase once the upper vortex opens into an upper trough while merging with the upper trough associated with the incoming frontal cyclone. The shear should strip away Nicole's thunderstorms from its center which should help in the transition to non-tropical at the end of the forecast period.

Thermodynamic Outlook for the Forecast Period...Nicole is currently a hurricane despite being over water temps below 26 deg C...due to the dynamics explained in the above current prognosis section. However once Nicole accelerates northeastward toward water temps in the low 20s in 72 hours...transition to non-tropical is likely.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 17)...85 mph maximum sustained wind hurricane centered at 39.5N-47W

48 Hr Forecast (0000Z Oct 18)...Strong non-tropical remnant gale centered at 42.5N-42.5W

Track Forecast...Nicole is expected to arc eastward and then northward per the above atmospheric outlook section. I have had to start a track forecast anew that cover the timeframe through 0000Z October 18 as Nicole has maintained tropical characteristics longer than I previously anticipated.

Intensity Forecast...Nicole is likely to maintain its current hurricane-force strength for at least the next 48 hours as it will again receive supportive upper divergence when the east side of the upper trough associated with the eastern Canada 992 mb frontal cyclone arrives.

Impact Forecast...The impact swath in the above forecast graphic is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track. Due to the large field of winds and waves...the north Atlantic will be treacherous for shipping interests in the next few days.

2016 Atlantic Hurricane Season Birdseye Discussion #146

By: NCHurricane2009, 4:36 PM GMT on October 13, 2016

**I will continue to be on vacation through the 23rd of October. Therefore my blog updates on the Atlantic tropics will likely be limited in the next week. In particular I will be flying internationally in the next 24 hours..so my next update will likely occur in a couple of days or so. Visit www.nhc.noaa.gov...www.wunderground.com/hurricane. ..or other sources on the Atlantic tropics for up to the minute latest information**

...THURSDAY OCTOBER 13 2016 12:35 PM EDT...
Nicole strengthens into a major hurricane and strikes Bermuda...damaging and possibly historic weather event for the island underway. Weather conditions will improve for the remainder of today as the eye is beginning to pull away. The hurricane is expected to transition into a strong non-tropical remnant gale affecting the north-central Atlantic marine interests in the next 48 hours. Visit www.nhc.noaa.gov for up to the minute latest information on Nicole.

The following statement concerns area of interest #1 marked over eastern North America in the atmospheric features chart below. Over the next week...a portion of the upper troughing currently over eastern North America will amplify while moving into the western Atlantic...in response to an amplifying upper ridge to be propped up by a strong frontal cyclone to develop behind it. It is possible that the amplifying western Atlantic upper trough could become a cut-off upper vortex that supports a subtropical disturbance just north of the Caribbean...or a tropical disturbance develops in the central Caribbean due to the outflow of a favorable upper ridge to develop in relatively higher pressures south of the upper trough.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0600Z and 0725Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...MAJOR HURRICANE NICOLE...
Current Prognosis...Nicole has strenghtened further into a major hurricane at category 3 strength while moving into Bermuda since my last blog post. The eye passed just southeast of the island with the northwestern eyewall making a direct and perhaps historically damaging strike on the island. Just prior to hitting Bermuda...Nicole acquired a 125 mph maximum sustained wind peak...which has recently come down to 120 mph as the hurricane begins to weaken due to increasing southwesterly vertical shear (see atmospheric outlook section below for the source of the shear). As of 1200Z earlier this morning the eye of Nicole was located at 31.8N-64.8W.

Atmospheric Outlook for the Forecast Period... Nicole is accelerating northeastward while the upper trough and surface frontal system currently over eastern North America moves into the Atlantic while already steering the hurricane. Strong upper southwesterly winds on the east side of the upper trough have begun to overspread and shear the hurricane. Nicole by 48 hours is expected to transition into a strong non-tropical gale supported by divergence on the east side of the incoming upper trough...affecting marine interests in the north-central Atlantic with large waves and strong winds.

Thermodynamic Outlook for the Forecast Period...On the latest forecast track...this system will be over favorable 27 to 28 deg C waters for only the early part of the forecat period...reaching waters below 26 deg C by 48 hours which will aid in the non-tropical transition noted at the end of the above atmospheric outlook section.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (1200Z Oct 14)...95 mph maximum sustained wind hurricane centered at 35.9N-58.5W

48 Hr Forecast (1200Z Oct 15)...Strong non-tropical remnant gale centered at 40N-50W

Track Forecast...Nicole is moving faster to the northeast than my prior forecast track...and also slightly more to the right while passing just southeast of Bermuda instead of over Bermuda. Therefore I have adjusted my forecast track to show a faster northeast track at a more right angle.

Intensity Forecast...Although Nicole is stronger than the previous forecast...I maintain the same intensity forecast as strong southwesterly shear will likely cause the hurricane to weaken briskly in the short-term.

Impact Forecast...The impact swath in the above forecast graphic is an extrapolation of the 11 AM EDT NHC tropical storm wind field along my forecast track. The severe weather conditions in Bermuda will gradually improve from this point forward as the eye of the hurricane is beginning to pull away.

2016 Atlantic Hurricane Season Birdseye Discussion #145

By: NCHurricane2009, 5:46 AM GMT on October 12, 2016

**I will be on vacation starting today on October 12...and will return from vacation on the 23rd. Therefore my blog updates on the Atlantic tropics will likely be limited during this time**

...WEDNESDAY OCTOBER 12 2016 1:47 AM EDT...
Nicole strengthens into a hurricane while getting ready to move towards Bermuda...and interests in Bermuda should finish preparations for strong hurricane conditions in the next 24 hours with Nicole expected to strengthen further. Bermuda is currently under a hurricane warning. See the special feature section below for more details. Visit www.nhc.noaa.gov for up to the minute latest information on Nicole...including the latest on the watches and warnings in effect for Bermuda.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1921Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...HURRICANE NICOLE...
Current Prognosis...Nicole has continued to become better organized and stronger in a low shear environment...with an eye popping open in its circular thunderstorm canopy. As a result...Nicole is now a strengthening category 1 hurricane with 90 mph maximum sustained winds at this time. As of 0000Z earlier this evening the center of Nicole was located at 27.2N-66.5W.

Atmospheric Outlook for the Forecast Period...The prior northward drift of Nicole has changed to a westward direction as the 1031 mb surface ridge over the eastern US influences the steering while moving into the Atlantic. By 48 to 72 hours Nicole is expected to accelerate northeastward and very likely pass over or very close to Bermuda...while the upper trough and surface frontal system currently over central and eastern North America eventually moves into the Atlantic with a large enough ridge weakness to kick Nicole out to sea.

Thermodynamic Outlook for the Forecast Period...On the latest forecast track...this system will be over favorable 29 to 28 deg C waters. By 72 hours...this system will be crossing the 26 deg C isotherm into cooler waters which will aid in the non-tropical transition noted at the end of the intensity forecast section below.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 13)...110 mph maximum sustained wind hurricane centered just southwest of Bermuda at 28.2N-67W

48 Hr Forecast (0000Z Oct 14)...95 mph maximum sustained wind hurricane centered over Bermuda at 32.2N-65W

72 Hr Forecast (0000Z Oct 15)...Strong non-tropical remnant gale centered at 37.5N-59W

Track Forecast...Nicole is slightly southwest of my previous forecast track per the 0000Z center fix in the above current prognosis section...and therefore I have shifted my forecast points southwestward accordingly. However I have kept the 72 hour forecast position as far to the northeast as the previous forecast to keep up with the lastest computer model runs that show a fast northeastward acceleration.

Intensity Forecast...Nicole is above the previous intensity forecast...and even higher than the intensity forecast in discussion #143...and therefore the intensity forecast is raised above what was shown in discussion #143. The overhead cool core upper vortex appears to have reversed into a small warm core upper anticyclone by Nicole's thunderstorm latent heat release. Therefore not only is the shear favorably low...the upper outflow is now favorably high. My updated intensity forecast shows Nicole peaking as a high-end category 2 hurricane with 110 mph maximum sustained winds in 24 hours...but with the favorable conditions Nicole could rapidly strengthen into category 3. Weakening is then shown by 48 hours as shear is expected to increase when the upper trough over the central and eastern US moves into the Atlantic while delivering strong upper southwesterlies in Nicole's environment. By 72 hours...Nicole will likely transition into a non-tropical remnant gale supported by upper divergence on the east side of the upper trough.

Impact Forecast...The impact swath in the above forecast graphic is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track. Given the raised intensity forecast...interests in Bermuda should finish preparations in the next 24 hours for strong hurricane conditions as the forecast for Nicole to either pass over or very near Bermuda is holding.

2016 Atlantic Hurricane Season Birdseye Discussion #144

By: NCHurricane2009, 12:57 PM GMT on October 11, 2016

...TUESDAY OCTOBER 11 2016 8:58 AM EDT...
Nicole is expected strengthen into a hurricane while moving towards Bermuda in the next 48 hours...and therefore interests in Bermuda should begin preparations for hurricane conditions. Bermuda is currently under a tropical storm warning and hurricane watch. See the special feature section below for more details. Visit www.nhc.noaa.gov for up to the minute latest information on Nicole...including the latest on the watches and warnings in effect for Bermuda.

The following statement concerns area of interest #1 marked over the central Caribbean Sea in the atmospheric features chart below. A tropical wave moving westward through the region currently lacks significant thunderstorm activity. Although a portion of the favorable upper anticyclone currently near the Bahamas has been pushed southward toward the tropical wave...the tropical wave has not responded to these conditions and therefore tropical cyclone formation is not expected. This is my final statement on this system on this blog.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 0730Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...TROPICAL STORM NICOLE...
Current Prognosis...As the northerly vertical shear over Nicole has relaxed...the thunderstorm activity has become more symmetrically organized around the center. However the tropical storm so far has maintained strength at 60 mph maximum sustained winds. As of 0600Z earlier this morning the center of Nicole was located at 27N-65.9W.

Atmospheric Outlook for the Forecast Period...Nicole has continued to drift northward toward Bermuda while pulled by the cold front currently moving across the western Atlantic driven by the remnant gale of Matthew. The northward track is however beginning to slow down as the low-level ridge weakness associated with the front is too narrow to pull Nicole out to sea. It isn't until 72 to 96 hours until Nicole is expected to accelerate northeastward...perhaps over or very near Bermuda...while the upper trough and surface frontal system currently over central North America eventually moves into the Atlantic with a large enough ridge weakness to kick Nicole out to sea.

Thermodynamic Outlook for the Forecast Period...On the latest forecast track...this system will be over favorable 29 to 28 deg C waters. By the end of the forecast period...this system will be crossing the 26 deg C isotherm into cooler waters which will aid in the non-tropical transition noted at the end of the intensity forecast section below.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0600Z Oct 12)...75 mph maximum sustained wind hurricane centered south-southwest of Bermuda at 28.2N-66.2W

48 Hr Forecast (0600Z Oct 13)...85 mph maximum sustained wind hurricane centered just southwest of Bermuda at 30.5N-66.2W

72 Hr Forecast (0600Z Oct 14)...70 mph maximum sustained wind tropical storm centered just northeast of Bermuda at 34N-63.7W

96 Hr Forecast (0600Z Oct 15)...Strong non-tropical remnant gale centered at 38.5N-57.5W

Track Forecast...Nicole is slightly west of my previous forecast track per the 0600Z center fix in the above current prognosis section...and therefore I have shifted my forecast points westward accordingly. This is probably due to the fact the strong 1031 mb ridge over North America is having and will continue to have some westward steering influence on Nicole's short-term track as the ridge moves into the Atlantic.

Intensity Forecast...Although Nicole is near the previous intensity forecast...I have lowered the intensity forecast as the upper wind configuration is different than previously anticipated. Instead of the upper anticyclone from the Bahamas overspreading Nicole...instead the upper anticyclone has split into one over the northwest Caribban and another to the northeast of Nicole...with a less favorable cool core upper vortex forming over Nicole and in between the two anticyclones. Although the overhead upper vortex will keep shear low...it will not enhance the upper outflow like an overhead upper anticyclone would have done. Weakening is then shown by 72 hours as shear is expected to increase when the upper trough over the central US moves into the Atlantic while delivering strong upper southwesterlies in Nicole's environment. By 96 hours...Nicole will likely transition into a non-tropical remnant gale supported by upper divergence on the east side of the upper trough.

Impact Forecast...Impact swath in the above forecast graphic is an extrapolation of the 5 AM EDT NHC tropical storm wind field along my forecast track. Interests in Bermuda should begin preparations for hurricane conditions as the forecast for Nicole to either pass over or very near Bermuda is holding.

2016 Atlantic Hurricane Season Birdseye Discussion #143

By: NCHurricane2009, 8:39 AM GMT on October 10, 2016

...MONDAY OCTOBER 10 2016 4:40 AM EDT...
The following statement concerns area of interest #1 in the atmospheric features chart below. Matthew transitions into a non-tropical remnant gale offshore of the eastern United States. While supported by divergence on the east side of the upper trough emerging from eastern North America...Matthew will linger as a marine threat for a couple more days in the northwestern Atlantic while producing gale force winds and sea swells...with these swells affecting the eastern United States shore. As Matthew is no longer tropical...this is my final statement on this system on this blog.

Nicole has begun to strengthen to the south of Bermuda despite being under unfavorable northerly vertical shear. The shear is expected to later reduce such that Nicole is likely to strengthen further into a strong hurricane while moving towards Bermuda this week...and therefore interests in Bermuda should begin thinking about preparations for signficant hurricane conditions. See the special feature section below for more details. Visit www.nhc.noaa.gov for up to the minute latest information on Nicole.

In addition to Matthew and Nicole...see the following statement for one other area of interest...

The following statement concerns area of interest #2 marked over the central Caribbean Sea in the atmospheric features chart below. A tropical wave moving westward through the region currently lacks significant thunderstorm activity. This system may find more favorable conditions as it moves into the western Caribbean Sea in the next couple of days as a part of the favorable upper anticyclone currently near the Bahamas will be pushed southward toward the tropical wave by the upper trough currently over eastern North America.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1929Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...TROPICAL STORM NICOLE...
Current Prognosis...The northerly vertical shear currently affecting Nicole has has not been strong enough to prevent the tropical storm from strengthening. In the last 24 hours the thunderstorm activity to the south has increasingly become better organized while becoming more wrapped around the center...and has strengthened to 65 mph maximum sustained winds. As of 0000Z the center of Nicole was located at 24.4N-65.3W.

Atmospheric Outlook for the Forecast Period...Nicole has begun to drift northward toward Bermuda while pulled by the cold front currently moving into the western Atlantic which contains the remnant gale of Matthew. The northward track is expected to slow down...perhaps even to a stall...as the low-level ridge weakness associated with the front will be too narrow to pull Nicole out to sea. It isn't until 96 to 120 hours until Nicole is expected to accelerate northeastward...perhaps over or very near Bermuda...while the upper trough and surface frontal system currently over western North America eventually moves into the Atlantic with a large enough ridge weakness to kick Nicole out to sea. Atmospheric conditions could become more favorable in 48 to 72 hours as the upper trough currently over eastern North America continues to push the favorable warm core upper anticyclone near the Bahamas toward Nicole's environment. But by 96 to 120 hours...conditions will become less favorable as the upper trough that is currently over western North America pushes the upper anticyclone eastward from Nicole and begin to shear the Nicole with strong upper southwesterly winds.

Thermodynamic Outlook for the Forecast Period...On the latest forecast track...this system will be over favorable 29 to 28 deg C waters. By the end of the forecast period...this system will be crossing the 26 deg C isotherm into cooler waters.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 11)...65 mph maximum sustained wind tropical storm centered at 27N-65.3W

48 Hr Forecast (0000Z Oct 12)...85 mph maximum sustained wind hurricane centered south of Bermuda at 28N-65.3W

72 Hr Forecast (0000Z Oct 13)...105 mph maximum sustained wind hurricane centered south of Bermuda at 29N-65.3W

96 Hr Forecast (0000Z Oct 14)...90 mph maximum sustained wind hurricane centered just east of Bermuda at 32.5N-64.3W

120 Hr Forecast (0000Z Oct 15)...75 mph maximum sustained wind hurricane centered at 37.5N-57.5W

Track Forecast...Nicole is slightly north of my previous forecast track per the above 0000Z center fix...and therefore I have shifted my forecast points slightly northward accordingly.

Intensity Forecast...Nicole is currently above my previous intensity forecast...and therefore I have raised the intensity forecast overall. I show brisk strengthening to hurricane status in 48 to 72 hours as the upper anticyclone with low shear and good upper outflow currently near the Bahamas will shift eastward over Nicole...and because Nicole will also be warm water. Weakening is then shown by 96 to 120 hours as shear is expected to increase per the above atmospheric outlook section. It is possible that at the end of the forecast period...or just slightly after...that Nicole transitions into a non-tropical remnant gale supported by upper divergence on the east side of the upper trough shearing Nicole.

Impact Forecast...Impact swath in the above forecast graphic is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track. Interests in Bermuda should begin thinking about preparations for hurricane conditions as the forecast for Nicole to either pass over or very near Bermuda is holding.

2016 Atlantic Hurricane Season Birdseye Discussion #142

By: NCHurricane2009, 5:52 AM GMT on October 09, 2016

...SUNDAY OCTOBER 9 2016 1:52 AM EDT...
After strongly impacting the eastern Carolinas...Matthew is beginning to curve eastward away from shore while it begins to transition into a non-tropical remnant gale. See first special feature section below for more details. Visit www.nhc.noaa.gov for up to the minute latest information on Matthew...including all hurricane and tropical storm watches and warnings.

Nicole hanging on to the south of Bermuda as a tropical storm while it continues to be unfavorably sheared by upper northerly winds. The shear is expected to later reduce such that Nicole is likely to re-strengthen while moving northward towards Bermuda next week...therefore interests in Bermuda should carefully monitor the progress of this tropical storm. See second special feature section below for more details. Visit www.nhc.noaa.gov for up to the minute latest information on Nicole.

In addition to Matthew and Nicole...see the following statements for one other area of interest...

The following statement concerns area of interest #1 marked over the eastern Caribbean Sea in the atmospheric features chart below. A tropical wave moving westward through the region currently lacks significant thunderstorm activity. This system may find more favorable conditions as it moves into the western Caribbean Sea in the next few days as a part of the favorable upper anticyclone that was over Hurricane Matthew...currently near the Bahamas...will be pushed southward toward the tropical wave by the upper trough currently over eastern North America.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1929Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...HURRICANE MATTHEW...
Current Prognosis...After battering the eastern Carolinas with storm surge...heavy flooding rains...and damaging winds...Hurricane Matthew is beginning to move eastward away from the Carolina coast. As of 0000Z earlier this evening Matthew was centered just east of Cape Fear North Carolina at 33.8N-77.5W. Over the last 24 hours Matthew has further weakened to a minimal category 1 with 75 mph maximum sustained winds due to a combination of increasing southerly vertical shear applied by the upper trough in eastern North America and land interaction. Satellite and radar show that the thunderstorm activity has dissipated over and south of the hurricane's core...and only remains well north of the core due to the shear. The thunderstorm activity north of the core is being supported by surface convergence associated with the upper trough's surface cold front...and also by the upper divergence on the east side of the upper trough.

Atmospheric Outlook for the Forecast Period...The upper trough and surface 992 mb frontal cyclone currently over eastern North America is nearing from the west and exerting influence such that the track of the hurricane is bending increasingly eastward. Matthew is now expected to transition into a strong non-tropical gale along the cold front of the frontal cyclone to be supported by the divergence on the east side of the upper trough. While becoming one with the surface cold front...the remnants of Matthew are now expected to move east with the front and pass just north of Bermuda.

Thermodynamic Outlook for the Forecast Period...Although Matthew is over a sharp gradient of sea-surface temps along the North Carolina coast where waters quickly cool to 26 deg C...Matthew will be curving eastward into waters above 26 deg C in the next 24 hours. However due to the incoming cold front per the above atmoshperic outlook section...Matthew is not expected to retain its tropical characteristics while moving back toward warmer water.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 10)...Strong non-tropical remnant gale centered between Bermuda and the Carolinas at 33.8N-71W

Track Forecast...Per the 0000Z center fix in the above current prognosis...Matthew is once again further north than my previous forecast while reaching 33.8N latitude and already passing Cape Fear about 6 hours ahead of schedule. With Matthew's recent history of being faster than prior forecasts...I have updated the eastward-curving track forecast to be notably faster than the previous and take Matthew further out to sea to 71W by 0000Z October 10 (the prior forecast had Matthew at 72.5W for 0600Z October 10).

Intensity Forecast...As Matthew transitions to non-tropical...it will retain hurricane force winds near the center for a few more hours...and tropical storm force winds for a period of time while supported by divergence on the east side of the incoming upper trough.

Impact Forecast...Impact swath is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track. Rainfall statement in the above forecast graphic is based on the latest doppler radar presentation.

...SPECIAL FEATURE...TROPICAL STORM NICOLE...
Current Prognosis...Just as it appeared Nicole would weaken to tropical depression status under northerly vertical shear...the tropical storm has fired renewed thunderstorm activity close to and south of the cloud swirl center and at this time Nicole is retaining 50 mph maximum sustained winds. As of 0000Z earlier this evening Nicole was centered at 25N-65.5W...and the latest satellite loop shows a continual southward drift...perhaps with some eastward component in the drift as the center might be trying to re-generate toward the strongest thunderstorm that are southeast of the center.

Atmospheric Outlook for the Forecast Period...Nicole has continued to drift southward under the influence of the 1026 mb surface ridge that has moved into the northwest Atlantic. The ridge has not been able to steer Nicole westward as it appears the 1000 mb surface frontal depression and shortwave upper trough to the northeast is imparting an equal and oppostie eastward drag. The southward-drifitng track is expected to eventually reverse northward toward Bermuda while pulled by the cold front currently over eastern North America (which will feature the remnants of Matthew) as the front moves into the Atlantic and passes north of Nicole. However the northward track may slow down or even stall as the low-level ridge weakness associated with the front will be too narrow to pull Nicole out to sea. It isn't until the end of the 120-hour forecast period until Nicole is expected to accelerate northeastward...perhaps over or very near Bermuda...while the upper trough and surface frontal system currently moving into western North America eventually moves into the Atlantic with a large enough ridge weakness to kick Nicole out to sea. On a final note...atmospheric conditions could become more favorable in 72 to 96 hours as the upper trough currently over eastern North America continues to shear away the favorable warm core upper anticyclone that was over Matthew while sending it eastward toward Nicole's environment. But by 120 hours...conditions will become less favorable as the upper trough that is currently over western North America will push the upper anticyclone eastward from Nicole and begin to shear the Nicole with strong upper southwesterly winds.

Thermodynamic Outlook for the Forecast Period...On the latest forecast track...this system will be over rather favorable 29 to 30 deg C waters. By the end of the forecast period...this system will be over still favorable 28 deg C waters near Bermuda.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 10)...50 mph maximum sustained wind tropical storm centered at 23.5N-65W

48 Hr Forecast (0000Z Oct 11)...50 mph maximum sustained wind tropical storm centered at 26N-65W

72 Hr Forecast (0000Z Oct 12)...70 mph maximum sustained wind tropical storm centered south of Bermuda at 27N-65W

96 Hr Forecast (0000Z Oct 13)...90 mph maximum sustained wind hurricane centered south of Bermuda at 28N-65W

120 Hr Forecast (0000Z Oct 14)...75 mph maximum sustained wind hurricane centered just southeast of Bermuda at 31.5N-64W

Track Forecast...Once again I have adjusted the early part of my forecast track southward (with some eastward component) due to the initial storm motion noted in the above current prognosis section. The track forecast is also shifted eastward overall as Nicole has not been able to make any westward progress for the reasons noted in the early part of the above atmospheric outlook section.

Intensity Forecast...Nicole is currently above my previous intensity forecast...and therefore I have raised the intensity forecast overall. I show brisk strengthening to hurricane status in 72 to 96 hours as the upper anticyclone with low shear and good upper outflow that was over Matthew will shift eastward over Nicole...and because Nicole will also be over rather warm water. Weakening is then shown by 120 hours as shear is expected to increase per the above atmospheric outlook section.

Impact Forecast...Impact swath in the above forecast graphic is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track. The swath is slightly increased in size to reflect the anticipated strengthening. Interests in Bermuda should carefully monitor the progress of Nicole as it is now forecast to pass over or very near Bermuda by Thursday after it strengthens.

2016 Atlantic Hurricane Season Birdseye Discussion #141

By: NCHurricane2009, 12:23 PM GMT on October 08, 2016

...SATURDAY OCTOBER 8 2016 8:25 AM EDT...
After strongly impacting the Florida peninsula and southeastern Georgia...Matthew weakens but is still producing strong impacts in the eastern Carolinas. Preparations and necessary evacuations in the affected areas in the Carolinas should have been completed by now as weather conditons have detereorated. See first special feature section below for more details. Visit www.nhc.noaa.gov for up to the minute latest information on Matthew...including all hurricane and tropical storm watches and warnings.

Nicole rapidly weakens to the south of Bermuda while encountering a burst of northerly vertical wind shear. The shear could later reduce such that Nicole hangs around a few more days...and interests in Bermuda should monitor this system as a complicated steering pattern is creating uncertainty in the track forecast. See second special feature section below for more details. Visit www.nhc.noaa.gov for up to the minute latest information on Nicole.

In addition to Matthew and Nicole...see the following statements for two other areas of interest...

The following statement concerns area of interest #1 marked over the eastern Caribbean Sea in the atmospheric features chart below. A tropical wave moving westward through the region currently lacks significant thunderstorm activity. This system may find more favorable conditions as it moves into the western Caribbean Sea in the next few days as the favorable upper anticyclone that was over Hurricane Matthew will be pushed southward toward the tropical wave by the upper trough currently over eastern North America.

The following statement concerns area of interest #2 marked over the central tropical Atlantic in the atmospheric features chart below. The thunderstorm activity along the surface intertropical convergence zone (ITCZ) in this area has collapsed as the central Atlantic shortwave upper trough has shifted southward. The upper trough is pushing upper-level air toward the ITCZ and thus suppressing the poleward upper outflow that was previously supporting this activity. This is my final statement on this area of disturbed weather on this blog.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0130Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...HURRICANE MATTHEW...
Current Prognosis...After battering the east coasts of Florida and Georgia...Hurricane Matthew is moving northeastward onto the South Carolina coast with the northern part of the eyewall along the coast. As of 0600Z Matthew was centered at 31.8N-80.2W. Over the last 24 hours Matthew has weakened to category 2 with 105 mph maximum sustained winds due to a combination of increasing southerly vertical shear applied by the upper trough moving into eastern North America and land interaction. Satellite and radar show that the thunderstorm activity has become limited to the south of the hurricane's core...but has increased and become lopsided to the north of the core due to the vertical shear and due to supportive upper divergence on the east side of the incoming upper trough. This is resulting in widespread heavy rain across eastern Georgia...as well as most of the Carolinas and Virginia.

Atmospheric Outlook for the Forecast Period...The upper trough and surface 1000 mb frontal cyclone currently over eastern North America is nearing from the west and exerting influence such that the track of the hurricane is bending increasingly eastward. By 72 to 96 hours...Matthew is likely to turn southward and then westward while peforming a fujiwhara interaction with Nicole to its east...afterwards becoming steered by the 1027 mb surface ridge building behind the aforementioned frontal cyclone. Meanwhile atmoshperic conditions are becoming less favorable while upper southwesterlies ahead of the upper trough associated with the frontal cyclone are beginning to shear the hurricane.

Thermodynamic Outlook for the Forecast Period...In the next 24 hours Matthew will be nearing the sharp gradient of sea-surface temps along the North Carolina coast where waters quickly cool to 26 deg C...and this may aid in the weakening process that is underway. With the forecast looping Matthew back southward...Matthew could reach 29 to 30 deg C waters again by the end of the forecast period.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0600Z Oct 9)...85 mph maximum sustained wind hurricane centered over Cape Fear North Carolina at 33.8N-78W

48 Hr Forecast (0600Z Oct 10)...60 mph maximum sustained wind tropical storm centered between Bermuda and the Carolinas at 32.5N-72.5W

72 Hr Forecast (0600Z Oct 11)...50 mph maximum sustained wind tropical storm centered between Bermuda and Florida at 30N-72W

96 Hr Forecast (0600Z Oct 12)...Remnant low north of the western Bahamas centered at 27.5N-75W

Track Forecast...Per the 0600Z center fix in the above current prognosis...Matthew is more north than the previous forecast and so I have adjusted the short-term track northward. The later part of the forecast is shifted further east as the models continue to trend with a more amplified version of the incoming upper trough from eastern North America...and therefore the upper trough is more likely to pull Matthew further offshore before the surface ridge behind the upper trough exerts its influence on Matthew.

Intensity Forecast...Matthew is currently weaker than my previous intensity forecast as the shear is already underway per the above current prognosis section...and therefore I have lowered the intensity forecast.

Impact Forecast...Impact swath is an extrapolation of the 5 AM EDT NHC tropical storm wind field along my forecast track...with the swath shrunken by the 48 to 96 hour forecast positions to reflect the anticipated weakening of Matthew by that time. Severe impacts (damaging winds...damaging coastal storm surge...heavy flooding rain) is expected over the eastern Carolinas. Preparations and necessary evacuations should have been completed by now as weather conditons have detereorated. Some heavy rain with isolated flash flooding may also occur over the western Carolinas...Virginia...Maryland...and Delaware based on the current radar presentation.

...SPECIAL FEATURE...TROPICAL STORM NICOLE...
Current Prognosis...Nicole has rapidly weakened from a hurricane to a weak tropical storm under a burst of northerly shear applied by the shortwave upper trough that has neared from the northwest Atlantic and is passing Nicole just to the east. The shear has pushed all thunderstorm activity south of Nicole's cloud swirl center...with the thunderstorm activity becoming poorly-organized. As of 0600Z earlier this morning Nicole was centered at 26N-65.5W...with the latest satellite loop showing the tropical storm drifting southwestward.

Atmospheric Outlook for the Forecast Period...Nicole has begun moving southwestward and is likely to bend westward in track while steered by the 1025 mb ridge currenlty moving offshore from the northeastern United States. The track is more likely to bend northward by 48 hours while Nicole enters a fujiwhara with Hurricane Matthew to its west. The models have trended with a more amplified version of the upper trough currently over eastern North America...and at this time it appears Nicole could stall by 72 hours in a narrow low-level ridge weakness induced by the upper trough (this weakness is currently over the eastern US...betweeen the 1027 mb ridge over the central US and aforementioned 1025 mb ridge and will translate offshore toward Nicole by the end of the forecast period). Atmospheric conditions could become more favorable by the end of the forecast period as the upper trough continues to shear away the upper anticyclone that was over Matthew and send it eastward toward Nicole's environment.

Thermodynamic Outlook for the Forecast Period...On the latest forecast track...this system will be over 29 deg C waters supportive for tropical development.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0600Z Oct 9)...35 mph maximum sustained wind tropical depression centered at 25.5N-67.5W

48 Hr Forecast (0600Z Oct 10)...35 mph maximum sustained wind tropical depression centered south-souhtwest of Bermuda at 27.5N-69W

72 Hr Forecast (0600Z Oct 11)...35 mph maximum sustained wind tropical depression centered southwest of Bermuda at 30N-68.5W

96 Hr Forecast (0600Z Oct 12)...45 mph maximum sustained wind tropical storm centered southwest of Bermuda at 30N-68.5W

120 Hr Forecast (0600Z Oct 13)...45 mph maximum sustained wind tropical storm centered southwest of Bermuda at 30N-68.5W

Track Forecast...I have adjusted the early part of my forecast track southward as Nicole still has a south component in its track per the above current prognosis section. The later part of the forecast is shifted eastward as Matthew's forecast track has shifted eastward such that the fujiwhara interaction with Matthew is now expected at a more eastward location. I then show a stall by the end of the forecast period per the end of the above atmospheric outlook section.

Intensity Forecast...Nicole is currently lower than my previous intensity forecast...and therefore I have lowered the intensity forecast overall. However I currently show Nicole hanging on through 120 hours due to the potential for more favorable atmospheric conditions per the end of the above atmospheric outlook section.

Impact Forecast...Impact swath in the above forecast graphic is an extrapolation of the 5 AM EDT NHC tropical storm wind field along my forecast track. The swath is absent where I currently forecast Nicole to be below tropical storm force. At this time Nicole should only bring sea swells to the island of Bermuda while passing southwest of the island. However it is not clear if Bermuda could later be directly impacted due to the complicated steering pattern in Nicole's environment.

2016 Atlantic Hurricane Season Birdseye Discussion #140

By: NCHurricane2009, 6:01 AM GMT on October 07, 2016

**There have been technical difficulties uploading blog posts here over the last month and therefore there maybe times this blog is not updated for periods well over 24 hours. Continue visiting www.nhc.noaa.gov for up to the minute latest information on the Atlantic tropics**

...FRIDAY OCTOBER 7 2016 2:00 AM EDT...
Intense and dangerous Hurricane Matthew is currently exiting the northwestern Bahamas and is on its way to ride up the east coast of Florida in the next 24 hours. Severe impacts (damaging winds...damaging coastal storm surge...heavy flooding rain) is expected over much of the Florida peninsula and Florida east coast...as well as southeastern Georgia...and the southern tip of South Carolina in the next 24 hours. Preparations and necessary evacuations in the affected areas in Florida should have been completed by now as weather conditons have detereorated...and should be rushed to completion in southeastern Georgia and southern South Carolina by tomorrow morning. Preparations in northeastern South Carolina as well as eastern North Carolina should be underway due to a more northward track being possible. See first special feature section below for more details. Visit www.nhc.noaa.gov for up to the minute latest information on Matthew...including all hurricane and tropical storm watches and warnings.

Nicole rapdily strengthens into a category 2 hurricane while stalling to the south of Bermuda. Sea swells are only expected on the shores of Bermuda as Hurricane Nicole is forecast to turn westward without striking Bermuda directly. See second special feature section below for more details. Visit www.nhc.noaa.gov for up to the minute latest information on Nicole.

In addition to Matthew and Nicole...see the following statements for two other areas of interest...

The following statement concerns area of interest #1 marked over the central tropical Atlantic and southeastern Caribbean Sea in the atmospheric features chart below. A tropical wave and surface trough moving westward through the region currently lacks significant thunderstorm activity while entering an area of no upper divergence beneath an inverted upper trough also moving westward through the region. In addition to suppression from the inverted upper trough...this tropical wave may struggle with unfavorable shear due to an easterly jet on the south side of Hurricane Matthew's strong upper anticyclone. However the upper anticyclone is forecast to shift southward while pushed away from Matthew by the upper trough currently over central North America...and therefore this system may find more favorable conditions beneath the anticyclone as it moves into the western Caribbean in the next few days.

The following statement concerns area of interest #2 marked over the eastern and central tropical Atlantic in the atmospheric features chart below. A low-latitude upper ridge continues to produce enhanced divergence over the surface intertropical convergence zone (ITCZ)...and as a result an extensive region of thunderstorm activity continues. A 1007 mb surface low has formed in this activity. This disturbance is likely too far south at this time to obtain enough coriolis effect to develop...and should it shift north is likely to become unfavorably sheared by westerlies on the north side of the upper ridge and south side of the northwest Atlantic and central Atlantic upper troughs as both troughs get pushed southeastward toward this system by the upper outflows of Hurricanes Nicole and Matthew. Therefore tropical cyclone formation from this disturbance is not expected.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1927Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...MAJOR HURRICANE MATTHEW...
Current Prognosis...While centered at 26.8N-79W as of 0000Z earlier this evening...Hurricane Matthew is in the process of exiting the northwestern Bahamas and getting ready to ride north-northwestward up the east Florida coast for the next 24 hours while steered between what's left of the upper trough in the Gulf of Mexico (now an upper vortex in the western Caribbean Sea) and 1026 mb surface ridge over the northeastern United States. While finally re-establishing an organized core with pinhole eye...Matthew re-strengthened into a category 4 with 140 mph winds while pressures dropped to the upper 930s in mb...resulting in the hurricane severely slamming the northwestern Bahamas. Then this evening the hurricane re-weakened to a maximum category 3 with 130 mph maximum sustained winds while satellite showed the western rain bands of the hurricane fade. The aforementioned upper trough in the Gulf of Mexico had produced dry air west of Hurricane Matthew with its western upper convergence...and perhaps some of this dry air got wrapped into the west side of Matthew. However ominously the latest satellite frames show a recovery of the hurricane's west side...perhaps as the hurricane has mixed out the dry air. As a result Matthew could again become category 4. Regardless of category 3 or 4 strength...severe impacts (damaging winds...damaging coastal storm surge...heavy flooding rain) is expected over much of the Florida peninsula and Florida east coast...as well as southeastern Georgia...and the southern tip of South Carolina in the next 24 hours. Preparations and necessary evacuations in the affected areas in Florida should have been completed by now as weather conditons have detereorated...and should be rushed to completion in southeastern Georgia and southern South Carolina by tomorrow morning.

Atmospheric Outlook for the Forecast Period...Matthew continues to experience favorable atmospheric conditions while situated beneath an upper anticyclone keeping the vertical shear low and upper outflow high. By 24 to 72 hours...the upper trough and surface 1001 mb frontal cyclone currently moving into eastern North America will be nearing from the west and exerting influence such that the north-northwestward track bends more eastward. By 96 to 120 hours...Matthew is likely to turn southward and then westward while peforming a fujiwhara interaction with Hurricane Nicole to its east...afterwards becoming steered by a strong surface ridge forecast to build behind the aforementioned frontal cyclone. Meanwhile atmoshperic conditions will start to become less favorable by 24 to 72 hours while upper southwesterlies ahead of the upper trough associated with the frontal cyclone begin to shear the hurricane. Models now are trending back with a more amplified version of the upper trough...and so despite Matthew dipping southward in track in 96 to 120 hours the shear is currently expected to be strong as the more amplified upper trough will have a further south reach as well.

Thermodynamic Outlook for the Forecast Period...In the next 24 hours Matthew will be moving into slighlty less warm but still very supportive 29 deg C waters. By 48 and 72 hours...due to the more northward adjusted track...Matthew may near the sharp gradient of sea-surface temps with waters quickly cooling to 26 deg C which may aid in the weakening process of the hurricane during that time. With the forecast looping Matthew back southward...Matthew could reach 29 to 30 deg C waters again by the end of the 120-hour forecast period.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 8)...145 mph maximum sustained wind hurricane centered just offshore of northeast Florida at 30N-80.5W

48 Hr Forecast (0000Z Oct 9)...115 mph maximum sustained wind hurricane centered on the northern South Carolina coast at 33N-79.5W

72 Hr Forecast (0000Z Oct 10)...85 mph maximum sustained wind hurricane centered offshore of the Carolinas at 33N-76W

96 Hr Forecast (0000Z Oct 11)...60 mph maximum sustained wind tropical storm centered offshore of Georgia and northeast Florida at 30.5N-79W

120 Hr Forecast (0000Z Oct 12)...35 mph maximum sustained wind tropical depression over the Florida peninsula and dissipating into a remnant low...centered at 28N-82W

Track Forecast...Per the 0000Z center fix in the above current prognosis...Matthew is more northwest compared to my previous forecast track and so my forecast track tonight is adjusted north and west not only because of the initial position of the storm...but because the models have trended back toward a slightly more amplified version of the upper trough currently moving into eastern North America. A more amplified upper trough will be able to pull Matthew a little more northward before it loops back south.

Intensity Forecast...Although Matthew is on par with the prior forecast...I have slighlty raised the intensity forecast for 24 hours as Matthew's current satellite signature is highly organized more than its ever been since departing eastern Cuba a couple of days ago. The intensity forecast is kept the same for 48 and 72 hours while depicting weakening from the expected unfavorable shear...and the intensity forecast is lowered by the end of the forecast period as the shear is expected to be stronger per the end of the above atmospheric outlook section.

Impact Forecast...Impact swath is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track...with the swath shrunken by the 96 to 120 hour forecast positions to reflect the anticipated weakening of Matthew by that time. Weather conditions will improve this morning in the northwestern Bahamas as Matthew pulls away. Severe impacts (damaging winds...damaging coastal storm surge...heavy flooding rain) is expected over much of the Florida peninsula and Florida east coast...as well as southeastern Georgia...and the southern tip of South Carolina in the next 24 hours. Preparations and necessary evacuations in the affected areas in Florida should have been completed by now as weather conditons have detereorated...and should be rushed to completion in southeastern Georgia and southern South Carolina by tomorrow morning. Preparations in northeastern South Carolina as well as eastern North Carolina should be underway due to a more northward track being possible per the above track forecast section.

...SPECIAL FEATURE...HURRICANE NICOLE...
Current Prognosis...Its hurricanes galore in the Atlantic...with Nicole now joining Matthew at hurricane strength. Its compact circular thunderstorm mass developed a pinhole eye and Nicole has rapidly intensified into a category 2 hurricane with 105 mph maximum sustained winds. Just after sunset however...the pinhole eye has disappeared with the thunderstorm mass becoming a bit lopsised to the south of the center...perhaps an early sign of northerly vertical shear as the shortwave upper trough that has emerged into the northwest Atlantic from the northeastern US nears Nicole. As of 0000Z earlier this evening Nicole stalled while centered at 27.5N-65W...and the latest satellite loop suggests a slight south-southeast drifting motion may be developing.

Atmospheric Outlook for the Forecast Period...Steering-wise...Nicole has stalled as the 1009 mb frontal depression in the northwest Atlantic is moving eastward and away while leaving the hurricane behind pinned between three high pressure systems (the 1026 mb surface ridge over the northeastern United States...1020 mb surface ridge to the east of the hurricane...and Matthew's high pressure upper outflow to the west). Because the 1026 mb ridge is the strongest of the three high pressure systems...it is probable that Nicole will eventually turn more westward as the 1026 mb ridge enters the Atlantic and gets close enough to steer Nicole. The track is more likely to bend northward by 72 hours while Nicole enters a fujiwhara with Hurricane Matthew to its west...followed by a more westward and even west-southwest track by 96 to 120 hours as both Matthew and Nicole get steered by a strong surface ridge emerging from the United States.

Thermodynamic Outlook for the Forecast Period...On the latest forecast track...this system will be over 29 deg C waters supportive for tropical development.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 8)...85 mph maximum sustained wind hurricane centered south of Bermuda at 26.5N-65W

48 Hr Forecast (0000Z Oct 9)...85 mph maximum sustained wind hurricane centered southwest of Bermuda at 26.5N-67W

72 Hr Forecast (0000Z Oct 10)...60 mph maximum sustained wind tropical storm centered betweeen Bermuda and the east US coast at 29N-69W

96 Hr Forecast (0000Z Oct 11)...40 mph maximum sustained wind tropical storm centered between Bermuda and the east US coast at 31N-72W

120 Hr Forecast (0000Z Oct 12)...Remnant low centered at 30N-75W

Track Forecast...The main change with my forecast track is to adjust the forecast southward as Nicole has stalled early instead of continuing northwestward. Moreover the initial part of my forecast shows a southward drift as it appears the surface ridge emerging from the northeastern US is strong enough to push Nicole a bit southward as it nears...and in fact the above current prognosis section suggests a southward drift may be beginning. With Nicole being further south and my Matthew forecast being adjusted northward...Nicole will take longer to finish its Fujiwhara interaction with and get north of Matthew...and so the northward angle of my track forecast from 72 to 96 hours is increased.

Intensity Forecast...Nicole is currently higher than my previous intensity forecast...but I have made no changes to the early part of the intensity forecast as I expect Nicole to weaken from a burst of northerly shear to arrive in the next 24 hours from a southward-diving shortwave upper trough (in fact the above current prognosis section suggests this burst of shear may be starting). With the southward adjusted track forecast...it takes longer for Nicole to be hurtled northward by Matthew into the belt of shearing westerly upper-level winds expected to develop in advance of the upper trough currently over central North America (as this upper trough enters the Atlantic). Thus the later part of my intensity forecast is raised.

Impact Forecast...Impact swath in the above forecast graphic is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track. Nicole should only bring sea swells to the island of Bermuda while passing southwest of the island.

2016 Atlantic Hurricane Season Birdseye Discussion #139

By: NCHurricane2009, 5:42 AM GMT on October 06, 2016

**This blog post was intended to be posted at 1:35 AM EDT this morning. However technical difficulties occurred during the upload process overnight. There have been technical difficulties uploading blog posts here over the last month...therefore continue visiting www.nhc.noaa.gov for up to the minute latest information on the Atlantic tropics.**

...THURSDAY OCTOBER 6 2016 1:35 AM EDT...
Alert! There are multiple active tropical cyclones and areas of disturbed weather with effects to multiple land areas expected over the next few days. Please read all statements below for a full comprehension...

Intense and dangerous Hurricane Matthew moves on to pounding the central and western Bahamas after clearing Cuba and Haiti. On the current forecast Matthew will pass either very close to or make landfall on the Florida peninusla while re-strengthening into a very dangerous category 4 hurricane...and interests there should rush preparations to completion before this afternoon...as weather conditions will detereorate by the afternoon and evening. Preparations should also be continuing across southeastern Georgia...and coastal Carolinas for tropical storm and possible strong hurricane conditions. Visit www.nhc.noaa.gov for up to the minute latest information on Matthew...including all hurricane and tropical storm watches and warnings.

Tropical Storm Nicole continues to strengthen as it begins curving northward towards Bermuda. Interests in Bermuda should continue to watch the progress of Nicole...see second special feature section below for more details. Visit www.nhc.noaa.gov for up to the minute latest information on Nicole.

In addition to Matthew and Nicole...see the following statements for two other areas of interest...

The following statement concerns area of interest #1 marked over the central tropical Atlantic in the atmospheric features chart below. The tropical wave approaching the Lesser Antilles and eastern Caribbean Sea has seen a signficant decrease in its thunderstorm activity while entering an area of less upper divergence beneath an inverted upper trough also entering the eastern Caribbean. In addition to suppression from the inverted upper trough...this tropical wave may struggle with unfavorable shear due to an easterly jet on the south side of Matthew's strong upper anticyclone. However the upper anticyclone is forecast to shift southward while pushed away from Matthew by the upper trough currently over central North America...and therefore this tropical wave may find more favorable conditions beneath the anticyclone as it moves into the western Caribbean in the next few days.

The following statement concerns area of interest #2 marked over the eastern and central tropical Atlantic in the atmospheric features chart below. The upper ridge that has persisted over the eastern half of the Atlantic tropics has been pushed southward by an upper trough that is a leftover feature from the upper vortex that spawned Tropical Storm Nicole...as this upper trough has also been pushed southeastward by the upper outflows of Nicole and Matthew. Moreover the upper trough currently over the northeastern United States coast is also expected to dive southeastward into this region while pushed by the outflows of Matthew and Nicole. The southward-shifted upper ridge is producing enhanced outflow over the surface intertropical convergence zone (ITCZ) in the area such that an oubreak of widespread thunderstorms has developed. This disturbance is likely too far south at this time to obtain enough coriolis effect to develop...and should it shift north is likely to become unfavorably sheared by westerlies on the north side of the upper ridge and south side of the aforementioned upper troughs. Therefore tropical cyclone formation from this disturbance is not expected.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1928Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...MAJOR HURRICANE MATTHEW...
Current Prognosis...As Hurricane Matthew barrels northwestward from Cuba and into the central and western Bahamas...it has continued to weaken and is now a category 3 with 115 mph maximum sustained winds with a 961 mb central pressure. Satellite showed the lack of an eye during the weakening process...and so it appears an eye wall replacement cycle that occurred while Matthew passed over Haiti and Cuba has disrupted the core. The most recent colorized infrared satellite images however ominously show an eye re-developing and Matthew is likely to re-strengthen shortly while it continues to batter the central and western Bahamas. As of 0000Z earlier this evening the eye of Matthew was located at 23N-76W.

Atmospheric Outlook for the Forecast Period...Matthew continues to experience favorable atmospheric conditions while situated beneath an upper anticyclone keeping the vertical shear low and upper outflow high. The hurricane's track is bending more westward as the steering upper trough over the Gulf of Mexico is weakening while the strong 1029 mb ridge currently over eastern North America begins to influence the steering. By 48 to 96 hours...the upper trough and surface 995 mb frontal cyclone currently moving into central North America will be nearing from the west while eroding the surface ridge to the north...which will cause Matthew's track to turn back northward and then more eastward. At the end of the 120-hour forecast period...Matthew is likely to turn southward and then westward while peforming a fujiwhara interaction with Nicole to its east...and then becomes steered by a strong surface ridge forecast to build behind the aforementioned frontal cyclone. Meanwhile atmoshperic conditions will start to become less favorable from 48 to 96 hours while upper southwesterlies ahead of the upper trough associated with the frontal cyclone begin to shear the hurricane. By 120 hours...the shear may relax a bit as Matthew likely dips south away from the shearing winds. It should be noted that after 120 hours the shear will likely increase again as the base of the upper trough with strong upper westerlies nears Matthew.

Thermodynamic Outlook for the Forecast Period...Matthew will be passing over rather favorable 30 to 31 deg C waters in Bahamas in the next 24 hours. By 48 hours the hurricane will be reaching slightly less warm 29 deg C waters...and then by 72 to 96 hours move into 28 deg C waters. With the forecast looping Matthew back southward...Matthew could reach 29 deg C waters again by the end of the 120-hour forecast period.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 7)...130 mph maximum sustained wind hurricane centered over the northwestern Bahamas at 25.5N-78W

48 Hr Forecast (0000Z Oct 8)...140 mph maximum sustained wind hurricane centered just east of Florida and north of the western Bahamas at 28.5N-79.5W

72 Hr Forecast (0000Z Oct 9)...115 mph maximum sustained wind hurricane offshore of Georgia and South Carolina centered at 31.5N-78.5W

96 Hr Forecast (0000Z Oct 10)...85 mph maximum sustained wind hurricane between the Carolinas and Bermuda...centered at 31.5N-75W

120 Hr Forecast (0000Z Oct 11)...85 mph maximum sustained wind hurricane between Florida and Bermuda....centered at 29N-78W

Track Forecast...So far Matthew is on par with the previous forecast and so I have made no changes through 72 hours. However beyond that time I am forced to make changes due to changes with other weather systems. The computer models continue to trend with a weaker and less amplified upper trough/surface frontal system to dive southeastward from Alaska in the next 24 hours. With the Alaskan frontal system being weaker...it will advect less warm air ahead of it...which will keep the warm core upper ridge ahead of it and behind the central North America upper trough re-curving Matthew less amplified...which in turn keeps the upper trough re-curving Matthew less amplified. At this point the re-curving upper trough is forecast to be so low in amplitude it quickly passes north of Matthew without trying to pick Matthew up...and therefore I have adjusted the later part of the forecast by showing a tighter clockwise loop turn than before due to less expected influence from the upper trough and more influence from the strong surface ridge to build behind the upper trough. Another reason for tightening the forecast loop is due to the westward adjusment in Nicole's forecast which will move Nicole closer to Matthew such that they go into a Fujiwhara interaction with each other.

Intensity Forecast...I have lowered the intensity forecast for Matthew for the next 24 hours due to the lower current initial strength of the hurricane...and still show re-strengthening. In fact my intensity forecast for 48 and 72 hours (0000Z October 8 and 0000Z October 9) is higher than the previous due to models showing the upper trough from central North America being less amplified while it recurves Matthew...which will reduce the shear from the upper trough during this timeframe. The intensity forecast for 96 hours (0000Z October 10) is the same as previous however as the strong shear from the upper trough finally reaches the hurricane. I show no weakening for 120 hours (0000Z October 11) as the shear may relax per the end of the above atmospheric outlook section.

Impact Forecast...Impact swath is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track. The most intense and destructive weather in the Bahamas during the next 24 hours...courtesy of coastal storm surge and very high winds...is expected on the islands where the eye passes over or near. On the current forecast Matthew will pass either very close to or make landfall on the Florida peninusla while re-strengthening into a very dangerous category 4 hurricane...and interests there should rush preparations to completion before this afternoon...as weather conditions will detereorate by the afternoon and evening. Preparations should also be continuing across southeastern Georgia...and coastal Carolinas for tropical storm and possible strong hurricane conditions.

...SPECIAL FEATURE...TROPICAL STORM NICOLE...
Current Prognosis...Nicole has the classic satellite appearance of a developing but also compact tropical storm with a well-organized circular thunderstorm mass. Albeit the mass is a bit displaced to the southeast of the center from some northelry shear from Hurricane Matthew's upper-level outflow. Latest satellite-derived upper-level winds shown in the above atmospheric features chart continues to show a small warm core upper ridge over Nicole supported by its strong thunderstorms which are producing latent heat release...and this is highlighted by a blue H over the eastern part of Nicole in the chart. Nicole's small upper ridge is continuing to deflect most of the shear from Matthew's outflow and thus Nicole has continued to strengthen and is almost a hurricane. As of 0000Z the center of Nicole passed over 26N-63.5W.

Atmospheric Outlook for the Forecast Period...Steering-wise...Nicole is expected to be pinned between the upper anticyclonic outflow of Hurricane Matthew to the west...a surface ridge to the east as the 1013 mb frontal depression in the northwest Atlantic never gets strong enough to erode it...and 1029 mb surface ridge currently building behind the frontal depression. Therefore Nicole is likely to continue moving slowly northwestward and then northward toward the frontal depression...but then the frontal depression is expected to move eastward and away which will leave Nicole in between three high pressure systems (the two surface ridges and Matthew's high pressure upper outflow). The latest model runs indicate that the upper trough currently over central North America will be too weak (too low in amplitude) to erode the aformentioned 1029 mb ridge...and in the latest model runs this ridge is shown to be stronger such that I forecast a westward turn by 72 hours. I bend the track more northward at 96 hours while Nicole enters a fujiwhara with Hurricane Matthew to its west...followed by a more westward track again at 120 hours as both Matthew and Nicole get steered by a strong surface ridge emerging from the United States.

Thermodynamic Outlook for the Forecast Period...On the latest forecast track...this system will be over 28 to 29 deg C waters supportive for tropical development.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 7)...85 mph maximum sustained wind hurricane centered south of Bermuda at 28N-65.5W

48 Hr Forecast (0000Z Oct 8)...85 mph maximum sustained wind hurricane centered south of Bermuda at 29.5N-66W

72 Hr Forecast (0000Z Oct 9)...85 mph maximum sustained wind hurricane centered west-southwest of Bermuda at 30N-68W

96 Hr Forecast (0000Z Oct 10)...50 mph maximum sustained wind tropical storm centered west of Bermuda at 32.5N-70W

120 Hr Forecast (0000Z Oct 11)...Dissipating remnant low centered between the Carolinas and Bermuda at 33N-73W

Track Forecast...Nicole is moving faster to the northwest than previously forecast and therefore the first part of the forecast shows a faster northwest and north initial motion. The later part of my forecast is adjusted significantly westward due to changes with the central North America upper trough in the latest model runs...see above atmospheric outlook section for details...

Intensity Forecast...Nicole is on par with my previous intensity forecast and so my forecast philosophy remains the same while predicting Nicole to become a hurricane while its warm core upper ridge (noted in the above current prognosis) continues to deflect the shear from Hurricane Matthew's upper outflow. However I do not show strenthening beyond category 1 as Nicole may have a higher chance of getting a burst of northerly shear by 48 hours when the shortwave upper trough currently over the northeast US coast dives southeastward around Hurricane Matthew's outflow and arrives over or just east of Nicole. I show rapid weakening and dissipation by 96 to 120 hours as the fujiwhara interaction with Hurricane Matthew would hurtle Nicole northward into the belt of strong shearing westerlies to be delivered by the upper trough currently over central North America. This belt of shearing upper winds could be exacerbated by Hurricane Matthew's outflow as Nicole approaches Matthew...making the rapid dissipation even more likely.

Impact Forecast...Impact swath in the above forecast graphic is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track. Interests in Bermuda should monitor the progress of Nicole...but it appears at this time Nicole will only bring sea swells to the island while eventually passing just south and west of the island.

2016 Atlantic Hurricane Season Birdseye Discussion #138

By: NCHurricane2009, 4:55 AM GMT on October 05, 2016

...WEDNESDAY OCTOBER 5 2016 12:54 AM EDT...
Alert! There are multiple active tropical cyclones and areas of disturbed weather with effects to multiple land areas expected over the next few days. Please read all statements below for a full comprehension...

Intense and dangerous Hurricane Matthew is moving into the Bahamas after dealing a severe strike to Haiti and eastern Cuba...and preparations in the Bahamas should be completed by now. Interests across the Florida peninsula...southeastern Georgia...and coastal Carolinas should be making preparations for tropical storm or strong hurricane conditions. More inland areas in the eastern Carolinas and the northeastern United States coast should still monitor Matthew in case the turn to the northeast out to sea does not occurr as sharply as currently forecast. See first special feature section below for additional details. Visit www.nhc.noaa.gov for up to the minute latest information on Matthew...including all hurricane and tropical storm watches and warnings.

The surface tropical low in the central Atlantic has strengthened into Tropical Storm Nicole....and will be slowly curving northward toward Bermuda over the next few days. Interests in Bermuda should watch the progress of Nicole...see second special feature section below for more details. Visit www.nhc.noaa.gov for up to the minute latest information on Nicole.

The following statement concerns area of interest #1 marked over the central tropical Atlantic in the atmospheric features chart below. What is left of the upper vortex that helped spawn Tropical Storm Nicole is an upper trough just east of the Lesser Antilles...and a surface tropical wave has seen a signficant increase in thunderstorm activity while reaching upper-level divergence on the east side of the upper trough. In the near-term...this tropical wave could bring heavy rain with flash flooding...as well as gusty winds...to the Lesser Antilles while entering the Caribbean Sea. In the longer-term...the upper trough is forecast to retrograde westward across the Caribbean about the south side of the upper anticyclone of Hurricane Matthew. Therefore this tropical wave could face suppression while first passing directly below the upper trough axis...and then face unfavorable shear due to an easterly jet on the south side of Matthew's strong upper anticyclone. However the upper anticyclone is forecast to shift southward while pushed away from Matthew by the upper trough currently over western North America...and therefore this tropical wave may find more favorable conditions beneath the anticyclone as it moves into the western Caribbean in the next few days.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1929Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...MAJOR HURRICANE MATTHEW...
Current Prognosis...After striking the western tip of Haiti's southern peninsula earlier today...Hurricane Matthew has continued northward with the eye now striking the eastern tip of Cuba. Weather conditions have improved across Jamaica...and will improve across Haiti...the Dominican Republic...and eastern Cuba in the next 24 hours. However weather conditions across the Bahamas will detereorate in the next 24 hours as the hurricane moves in and preparations in the Bahamas should have been completed by now. Matthew's sharp pinhole eye on satellite has become replaced by a larger and more faint eye...indicating an eye wall replacement cycle is underway. Combined with the land interaction further disrupting Matthew's core...Matthew has weakened. More specifically...the central pressure has risen to 950 mb from 943 mb twenty-four hours ago while the maximum sustained winds at the surface have declined from 145 mph to 130 mph. As of 0000Z earlier this evening the eye of Matthew was located at 20.0N-74.3W

Atmospheric Outlook for the Forecast Period...Matthew continues to experience favorable atmospheric conditions while situated beneath an upper anticyclone keeping the vertical shear low and upper outflow high. The hurricane has continued accelerating northward in track while it neared the steering upper trough currently located over the Gulf of Mexico and Yucatan peninsula. In the next 24 to 48 hours however...the steering upper trough is forecast to dissipate...with the strong 1030 mb ridge currently over eastern North America being situated north of the hurricane such that the hurricane's northward progress slows and the track obtains a westward angle. By 72 to 120 hours...the upper trough and surface frontal system currently over western North America will be nearing from the west while eroding the surface ridge to the north...which will cause Matthew's track to turn back northward and then more eastward. Atmoshperic conditions will start to become less favorable during this time as well while upper southwesterlies ahead of the incoming upper trough begin to shear the hurricane. The forecast situation with Matthew continues to be dynamic and ever-changing...see the track forecast section below for more info on the latest changes...

Thermodynamic Outlook for the Forecast Period...Matthew will be passing over rather favorable 30 to 31 deg C waters in Bahamas in the next 48 hours. By 72 hours the hurricane will be reaching slightly less warm 29 deg C waters...and then by 96 to 120 hours move into 28 deg C waters.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 6)...140 mph maximum sustained wind hurricane centered between Cuba and the Bahamas at 23N-76W

48 Hr Forecast (0000Z Oct 7)...140 mph maximum sustained wind hurricane centered over the northwestern Bahamas at 25.5N-78W

72 Hr Forecast (0000Z Oct 8)...130 mph maximum sustained wind hurricane centered just east of Florida and north of the western Bahamas at 28.5N-79.5W

96 Hr Forecast (0000Z Oct 9)...110 mph maximum sustained wind hurricane offshore of Georgia and South Carolina centered at 31.5N-78.5W

120 Hr Forecast (0000Z Oct 10)...85 mph maximum sustained wind hurricane between the Carolinas and Bermuda...centered at 32.5N-72.5W

Track Forecast...Matthew is slightly south of my previous forecast and therefore I have adjusted all forecast points southward. For the first 48 hours...I have adjusted the track forecast more westward as the computer model forecast for a slower-moving upper trough/surface frontal system from western North America continue to hold...which will prevent this system from eroding the surface ridge north of Matthew such that the ridge pushes Matthew more west. But by 72 hours and beyond...my forecast track is further east...then eventually further southeast of my previous track forecast. The biggest reason for my sharp eastward turn in the track forecast has to do with the less-amplified nature in the computer models of an upper trough/surface frontal system to dive southeastward from Alaska in the next 48 hours. With the Alaskan frontal system being weaker...it will advect less warm air ahead of it...which will keep the warm core upper ridge ahead of it and behind the western North America upper trough re-curving Matthew less amplified...which in turn keeps the upper trough re-curving Matthew less amplified. Computationally less-amplified upper troughs move faster to the east...and so after 48 hours the models now show the re-curving upper trough reaching Matthew faster and turning Matthew eastward sooner. A second reason for my forecast sharp eastward turn is the overall southward adjusted forecast makes it less likely Matthew gets pulled into the surface front passing by to the north associated with the re-curving upper trough...and more likely Matthew gets held back towards the south by the strong surface ridge forecast to build behind the front. The last reason I prefer a sharp eastward turn is the development and rapid strengthening of Tropical Storm Nicole...with Nicole's surface low pressure field possibly gravitating Matthew more eastward.

Intensity Forecast...Matthew is on par with my previous intensity forecast and therefore my intensity forecast is kept mostly the same. Re-strengthening is first shown as Matthew clears eastern Cuba while atmospheric and thermodynamic conditions remain favorable. Weakening is then shown by 72 hours and beyond as Matthew begins to encounter southwesterly vertical shear per the above atmospheric outlook section. My intensity forecast is for 0000Z October 8 is somewhat raised as my southward adjusted track makes Matthew take longer to reach the shearing upper southwesterly winds to the north. The increase in the intensity forecast is not as big for 0000Z October 9 and onwards due to the strength of the shearing southwesterly upper winds Matthew is forecast to experience.

Impact Forecast...Impact swath is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track. Preparations in the Bahamas should have been completed by now as weather conditions will detereorate in the next 24 hours. The most intense and destructive weather...courtesy of coastal storm surge and very high winds...is expected on the islands in the Bahamas where the eye passes over or near. The updated forecast track increases the threat to the Florida peninsula and southeastern Georgia...but reduces the threat to the eastern Carolinas while now confining the strongest impacts to the coast. Should the sharp eastward turn not materialize...the threat to more inland areas of the eastern Carolinas and perhaps the northeastern United States coast would increase. As such...interests across the Florida peninsula...southeastern Georgia...and coastal Carolinas should be making preparations for tropical storm and possible strong hurricane conditions. More inland areas in the eastern Carolinas and the northeastern United States coast should still monitor Matthew in case the forecast sharp eastward turn does not materialize.

...SPECIAL FEATURE...TROPICAL STORM NICOLE...
Current Prognosis...The surface tropical low in the central Atlantic has curiously slowed down and intensified more than expected and is now Tropical Storm Nicole. Latest satellite-derived upper-level winds shown in the above atmospheric features chart show the formation of a small area of warm core anticyclonic upper ridging...and this is highlighted by a blue-zig-zag line over the eastern part of Nicole in the chart. It appears the strong thunderstorm activity of this system has produced enough latent heat release to support this small upper ridge...with the upper ridge deflecting the shear from Hurricane Matethew's upper outflow and allowing this system to strengthen. Because strengthening Nicole is likely a taller system...the slow-down in the northwest track may be Nicole feeling steering influence from Matthew's upper outflow. As of 0000Z the center of Nicole was located at 24N-61W...which means Nicole has only moved 1N latitude and 1W longitude in the last 24 hours. Under lower wind shear...the thunderstorm mass that was displaced to the east of the swirl center has begun to wrap over the center in spiral bands.

Atmospheric Outlook for the Forecast Period...Steering-wise...Nicole is expected to be pinned between the upper anticyclonic outflow of Hurricane Matthew to the west...1022 mb surface ridge to the northeast as the 1014 mb frontal depression in the northwest Atlantic never gets strong enough to erode it...and 1030 mb surface ridge currently building behind the frontal depression. Therefore Nicole is likely to continue moving slowly northwestward and then northward toward the frontal depression...but then the frontal depression is expected to move eastward and away which will likely cause Nicole to stall while trapped between the three high pressure systems (the two surface ridges and Matthew's high pressure upper outflow). Eventually the 1030 mb ridge will shift east and merge with the 1022 mb ridge...and by the end of the forecast period Nicole is expected to accelerate northward in strengthening low-level southerly flow between the combined ridge and Matthew approaching from the west.

Thermodynamic Outlook for the Forecast Period...On the forecast track...this system will be over 28 to 29 deg C waters supportive for tropical development.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 6)...70 mph maximum sustained wind tropical storm centered at 25N-62W

48 Hr Forecast (0000Z Oct 7)...85 mph maximum sustained wind hurricane centered at 26N-63W

72 Hr Forecast (0000Z Oct 8)...85 mph maximum sustained wind hurricane centered southeast of Bermuda at 27.5N-63.5W

96 Hr Forecast (0000Z Oct 9)...85 mph maximum sustained wind hurricane centered southeast of Bermuda at 27.5N-63.5W

120 Hr Forecast (0000Z Oct 10)...85 mph maximum sustained wind hurricane centered just east-southeast of Bermuda at 29.5N-63.5W

Track Forecast...Nicole is moving much slower to the northwest...and the first part of my updated forecast is based on the current 1N and 1W per 24 hour progress noted in the above current prognosis. The sluggish track forecast is then bent northward...followed by a stall...followed by a northward acceleration by 120 hours per the above atmospheric outlook section.

Intensity Forecast...The above intensity forecast assumes Nicole will continue to strengthen into a hurricane as its warm core upper ridge (noted in the above current prognosis) continues to deflect the shear from Hurricane Matthew's upper outflow. However I do not show strenthening beyond category 1 as Nicole may have a higher chance of getting a burst of northerly shear by 72 hours when the shortwave upper trough currently over the northeast US coast dives southeastward around Hurricane Matthew's outflow and hits Nicole. Another reason I do not show strength beyond category 1 is the slow track may cause Nicole to upwell cooler waters below the sea surface. I could possibly show more strengthening at the end of the forecast period after the shortwave upper trough shifts southward and away while Matthew's more favorable warm core upper anticyclone becomes sheared eastward and spreads over Nicole as an upper ridge axis...but because I am already going out on a limb by an already-aggressive intensity forecast that is well above the NHC prefer not to do this at the moment.

Impact Forecast...Impact swath in the above forecast graphic is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track...with some growth in the swath to reflect my forecast strengthening. Interests in Bermuda should monitor the progress of Nicole...but it appears at this time Nicole will only bring sea swells to the island while eventually passing just east of the island.

2016 Atlantic Hurricane Season Birdseye Discussion #137

By: NCHurricane2009, 3:59 AM GMT on October 04, 2016

...TUESDAY OCTOBER 4 2016 12:00 AM EDT...
Intense and dangerous category 4 Hurricane Matthew is moving northward towards Jamaica...Haiti...eastern Cuba...and the Bahamas where weather conditions will detereorate in the next 24 hours...and preparations in these areas should have been completed by now. Even though winds are not expected to be high over the Dominican Republic...satellite imagery shows strong thudnerstorm activity well east of Matthew's core and therefore heavy rain with flash flooding potential will be possible over the Dominican Republic as well. The threat to the southeastern United States coast from Florida to the Carolinas has increased based on the latest computer model runs....and interests along the northeastern United States coast should monitor the progress of Matthew as it is not clear exactly how Matthew will track once it emerges from the Carolinas. See first special feature section below for additional details. Visit www.nhc.noaa.gov for up to the minute latest information on Matthew...including all hurricane and tropical storm watches and warnings.

In addition to Matthew...see the following statements for two other areas of interest...

The following statement concerns area of interest #1 marked over the eastern tropical Atlantic in the atmospheric features chart below. The tropical wave west of the Republic of Cabo Verde has not become better organized while losing thunderstorm activity. Although upper-level winds are currently favorable for the tropical wave while embedded beneath an upper ridge axis with low shear and good upper outflow...the large upper anticyclone of Hurricane Matthew is expected to drive what's left of the central Atlantic upper vortex and shortwave upper trough emerging from the northeastern United States in a southward direction such that these features begin to produce a belt of unfavorable westerly vertical shear on their south sides. Conditions will later become less favorable for development as this tropical wave moves into the central Atlantic and belt of westerly shear...and therefore tropical cyclone formation is unlikely from this tropical wave. This is my final statement on this blog on this tropical wave.

The following statement concerns area of interest #2 marked over the central tropical Atlantic in the atmospheric features chart below. The surface tropical low in the area is producing a more impressive thunderstorm cluster...but the cluster is becoming seperated from the center as the upper outflow of Hurricane Matthew begins to shear this system. This system is likely to curve increasingly northward toward Bermuda in the next few days and interests in Bermuda should monitor this system. However any tropical cyclone that develops from this surface low is likely to be weak while staying sheared by Hurricane Matthew's upper-level outflow. See second special feature section below for more details on this system.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1927Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...MAJOR HURRICANE MATTHEW...
Current Prognosis...Although aircraft reconaissance has found that the central pressure of Matthew has dropped to 934 mb...Matthew has not regained category 5 strength while maintaining 145 mph maximum sustained winds. The hurricane has not grown any larger/broader on satellite imagery nor has seen a growth in its tropical storm wind field to indicate that the low pressure field and thus the internal pressure gradient of Matthew has spread out. Perhaps then the pressures outside the storm are lower than before to explain the lack of wind speed increase despite the drop in pressure. The circular core of thunderstorms with pinhole eye has grown to a larger diameter while the storm mass that was east of the core has shrunken into skeletal spiral bands...giving Matthew a more symmetric appearance on satellite. As of 0000Z the pinhole eye of Matthew passed over 16.6N-74.6W while it continues northward...and weather conditions in Jamaica and Haiti will continue to detereorate tonight. Although winds will not be strong...rainfall intensity across the Dominican Republic will also increase tonight. By tomorrow afternoon and evening...the weather conditions in the eastern half of the Bahamas and eastern Cuba will have detereorated.

Atmospheric Outlook for the Forecast Period...Matthew continues to experience favorable atmospheric conditions while situated beneath an upper anticyclone keeping the vertical shear low and upper outflow high. The hurricane is accelerating northward in track while getting closer to a steering upper trough currently located over the Gulf of Mexico and Yucatan peninsula. By 48 to 72 hours...the steering upper trough is forecast to dissipate...with the strong 1026 mb ridge currently over eastern North America being situated north of the hurricane such that the hurricane's northward progress slows and the track obtains a westward angle. The bend to the west is not expected to be sharp as the shortwave upper trough currently over the northeastern US moves into the northwest Atlantic...with its eastern upper-level divergence dropping surface pressures to the northeast of Matthew. By 96 to 120 hours...the upper trough and surface frontal system currently over western North America will be nearing from the west while eroding the surface ridge to the north...which will cause Matthew's northward rate to once again increase. Atmoshperic conditions will start to become less favorable during this time as well while upper southwesterlies ahead of the incoming upper trough begin to shear the hurricane. The computer models have delayed the forecast northward turn at the end of the 120 hour forecast period while showing a more amplified upper trough that takes longer to arrive and erode the surface ridge (typically more amplified troughs or ridges take longer to move to the east). Perhaps this is the model response as the upper trough becomes better sampled by weather stations while moving into North America...and now the threat to the eastern United States has increased.

Thermodynamic Outlook for the Forecast Period...Matthew will be passing over rather favorable 30 to 31 deg C waters in the Caribbean and over the Bahamas in the next 72 hours. By 96 hours the hurricane will be reaching slightly less warm 29 deg C waters...and then by 120 hours approach a sharp gradient near the Carolina coast where water temps quickly change to 26 deg C.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 5)...130 mph maximum sustained wind hurricane emerging from the northeast coast of Cuba and heading toward the eastern Bahamas...centered at 21.1N-75W

48 Hr Forecast (0000Z Oct 6)...140 mph maximum sustained wind hurricane over the central and western Bahamas...centered at 24.1N-76.5W

72 Hr Forecast (0000Z Oct 7)...140 mph maximum sustained wind hurricane centered over the northwestern Bahamas at 26.5N-77.5W

96 Hr Forecast (0000Z Oct 8)...120 mph maximum sustained wind hurricane centered just east of Florida and north of the western Bahamas at 29.5N-78.5W

120 Hr Forecast (0000Z Oct 9)...105 mph maximum sustained wind hurricane approaching landfall on the Carolina coast at 32.5N-78.5W

Track Forecast...The first part of the forecast is the same as Matthew is essentially following the previous forecast. However by 96 and 120 hours...the track is shifted westward in response to the models delaying the arrival of the recurving upper trough from western North America per the above atmospheric outlook section.

Intensity Forecast...I have lowered the intensity forecast as Matthew has not re-strengthened into a category 5 hurricane. The intensity forecast still shows weakening through 0000Z October 5 due to land interaction with eastern Cuba that will occur in the next 24 hours. Re-strengthening is then still shown after Matthew emerges from Cuba...but I do not show category 5 for that timeframe as Matthew moves into slighlty less oceanic heat. Weakening is then shown by 96 to 120 hours as Matthew begins to encounter southwesterly vertical shear and increasingly cooler waters per the above atmospheric and thermodynamic outlook sections. Despite the lowered intensity forecast the intensity for 96 hours (0000Z October 8) is the same as the previous as the delayed arrival of the upper trough from western North America reduces the initial shear from the trough. But the weakening rate for 120 hours (0000Z October 9) becomes more brisk as the shear signficantly increases.

Impact Forecast...Impact swath is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track. Preparations in Haiti...Jamaica...eastern Cuba...and the Bahamas should have been completed by now as weather conditions will detereorate in the next 24 hours. The most intense and destructive weather...courtesy of coastal storm surge and very high winds... will likely be over the western part of Haiti's southern peninsula...and then over the eastern tip of Cuba...and any of the islands in the Bahamas where the eye passes over or near. Satellite continues to show strong thunderstorm bands well east of Matthew's core...and therefore some heavy rainfall with flash flooding potential will also be possible over the Dominican Republic even though the winds will not be strong. The updated forecast track increases the threat to coastal Florida and Georgia...as well as the eastern Carolinas and interests in these locations are urged to watch Matthew very closely. Interests along the northeastern United States coast should also watch Matthew as it is not clear how Matthew will track exactly after emerging from the Carolinas.

...SPECIAL FEATURE...SURFACE LOW INVEST 98-L...
This special feature section is for area of interest #2 marked in the above atmospheric features chart.

Current Prognosis...The surface tropical low in the central Atlantic is producing a more impressive cluster of thunderstorms this evening...but the cluster has become displaced to the east-southeast of the swirl center which likely indicates that the northerly shear that Hurricane Matthew's upper outflow was expected to induce is beginning. As of 0000Z the surface low was centered at 23N-60W. This is slighlty north and west of the previous forecast track and therefore the updated forecast track listed below is adjusted accordingly.

Atmospheric Outlook for the Forecast Period...The track is expected to bend increasingly northward...likely toward Bermuda...as this system moves into the western Atlantic while getting pulled into the low-level ridge weakness generated by the divergence on the east side of the shortwave upper trough emerging from the northeastern United States. Later in the forecast period this shortwave upper trough is expected to produce a surface frontal depression to the northeast that will likely pull this system northeastward. By the end of the 120 hour forecast...it appears this frontal depression will race eastward and away...causing this system to meander and drift back westward over or near Bermuda while becoming steered by the 1026 mb ridge currently over eastern Canada as this ridge moves into the northwest Atlantic. On the forecast track...this system will become sheared by upper northerlies on the east side of Hurricane Matthew's anticyclonic outflow and so the forecast shows this system staying a weak tropical cyclone thru the forecast period.

Thermodynamic Outlook for the Forecast Period...On the forecast track...this system will be over 28 to 29 deg C waters supportive for tropical development.

24 Hr Forecast (0000Z Oct 5)...35 mph maximum sustained wind tropical depression under northerly vertical shear centered at 25N-63W

48 Hr Forecast (0000Z Oct 6)...35 mph maximum sustained wind tropical depression under northerly vertical shear centered at 27.5N-65.5W

72 Hr Forecast (0000Z Oct 7)...35 mph maximum sustained wind tropical depression under northerly vertical shear centered just southwest of Bermuda at 30.5N-66.5W

96 Hr Forecast (0000Z Oct 8)...35 mph maximum sustained wind tropical depression under northerly vertical shear centered just east of Bermuda at 33.5N-64W

120 Hr Forecast (0000Z Oct 9)...35 mph maximum sustained wind tropical depression under northerly vertical shear centered just west of Bermuda at 32.5N-65.5W

2016 Atlantic Hurricane Season Birdseye Discussion #136

By: NCHurricane2009, 6:31 AM GMT on October 03, 2016

...MONDAY OCTOBER 3 2016 2:35 AM EDT...
Intense Hurricane Matthew will move northward towards Jamaica...Haiti...eastern Cuba...and the Bahamas in the next 48 hours where weather conditions will detereorate in the next 48 hours...and preparations in these areas should be nearing completion. Even though winds are not expected to be high over the Dominican Republic...satellite imagery shows strong thudnerstorm activity well east of Matthew's core and therefore heavy rain with flash flooding potential will be possible over the Dominican Republic as well. Interests across the southeastern United States coast should also monitor the progress of Matthew as it is not yet clear how close to the coast the hurricane will track after it emerges from the Bahamas. See first special feature section below for additional details. Visit www.nhc.noaa.gov for up to the minute latest information on Matthew...including all hurricane and tropical storm watches and warnings.

In addition to Matthew...see the following statements for two other areas of interest...

The following statement concerns area of interest #1 marked over the eastern tropical Atlantic in the atmospheric features chart below. The tropical wave west of the Republic of Cabo Verde has slightly become better organized but has not been able to maintain concentrated thunderstorm activity for a long period of time thus far. Additional development of this tropical wave is possible over the next few days as a more favorable upper ridge has developed to the southeast of the weakening upper vortex in the central tropical Atlantic and over this tropical wave. Therefore will continue to monitor this tropical wave.

The following statement concerns area of interest #2 marked over the central tropical Atlantic in the atmospheric features chart below. The surface low triggered by the divergence on the east side of the upper vortex that has persisted in this area has become better organized while reaching a belt of upper easterlies on the north side of the upper vortex. This belt of upper winds is keeping the vertical shear over the surface low favorably low while lined up with the current westward track of the surface low. And with this belt of upper winds persisting...tropical cyclone formation is becoming more likely. This system is likely to curve increasingly northward toward Bermuda in the next few days and interests in Bermuda should monitor this system. However any tropical cyclone that develops from this surface low is likely to be weak while later becoming sheared by Hurricane Matthew's upper-level outflow. See second special feature section below for more details on this system.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1929Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...MAJOR HURRICANE MATTHEW...
Current Prognosis...Matthew is slightly weaker but still an intense category 4 hurricane when compared to last evening...currently rated at 145 mph maximum sustained winds with a 943 mb surface central pressure. The hurricane continues to have its signature circular core with central pinhole eye...with comma shaped storm mass wrapped around the core to the east. As of 0000Z the eye of Matthew passed over 14.5N-75W while drifting slowly northward.

Atmospheric Outlook for the Forecast Period...Matthew continues to experience favorable atmospheric conditions while situated beneath an upper anticyclone keeping the vertical shear low and upper outflow high. The hurricane is drifting northward while becoming steered by a southern fracture upper trough located over the Gulf of Mexico and Yucatan peninsula...left behind by the deep-layered 1014 mb frontal cyclone currently over the eastern United States. The northward track is expected to become increasingly faster in the next 48 hours as the distance between Matthew and the steering southern fracture upper trough decreases. By 72 to 96 hours...the southern fracture upper trough is forecast to dissipate...with the strong surface ridge currently building behind the frontal cyclone increasingly slowing the northward progress while simultaneously bending the the track more westward. However a sharp bend to the west is not expected as the northern upper-level part of the deep-layered frontal cyclone will have shifted into the northwest Atlantic as a shortwave upper trough whose eastern divergence will drop surface pressures to the northeast of Matthew. By 120 hours...the upper trough and surface frontal system currently over western North America will be nearing from the west while eroding the surface ridge to the north...which will accelerate Matthew in a northward direction while southwesterly flow ahead of the upper trough begins to shear the hurricane.

Thermodynamic Outlook for the Forecast Period...Matthew will be passing over rather favorable 30 to 31 deg C waters in the Caribbean and over the Bahamas in the next 96 hours. By 120 hours the hurricane will be reaching slightly less warm 29 deg C waters.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 4)...160 mph maximum sustained wind hurricane centered southeast of Jamaica and southwest of Haiti at 16.5N-75W

48 Hr Forecast (0000Z Oct 5)...140 mph maximum sustained wind hurricane emerging from the northeast coast of Cuba and heading toward the eastern Bahamas...centered at 21.1N-75W

72 Hr Forecast (0000Z Oct 6)...150 mph maximum sustained wind hurricane over the central and western Bahamas...centered at 24.1N-76.5W

96 Hr Forecast (0000Z Oct 7)...150 mph maximum sustained wind hurricane centered over the northwestern Bahamas at 26.5N-77.5W

120 Hr Forecast (0000Z Oct 8)...120 mph maximum sustained wind hurricane centered east of Florida and north of the western Bahamas at 29.5N-77.5W

Track Forecast...Although Matthew is slightly southwest of the previous forecast...I have only adjusted my forecast points slightly to the south as satellite animation suggests Matthew is beginning to slowly turn northward along 75W longitude as the prior forecast suggested.

Intensity Forecast...Although Matthew has not re-strengthened into a category 5 hurricane...I have not changed the intensity forecast at this time and still show category 5 strength for 0000Z October 4 as the atmospheric and thermodynamic conditions that were in place when Matthew previously became category 5 are still in place. Weakening is shown from 0000Z October 4 to 0000Z October 5 due to forecast land interaton with eastern Cuba. Re-strengthening is then shown after Matthew emerges from Cuba...but I do not show category 5 for that timeframe as Matthew moves into slighlty less oceanic heat. Weakening is then shown by 120 hours as Matthew begins to encounter southwesterly vertical shear per the above atmospheric outlook section.

Impact Forecast...Impact swath is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track. Preparations in Haiti...Jamaica...eastern Cuba...and the Bahamas should be nearing completion as weather conditions will detereorate in the next 48 hours. Satellite continues to show strong thunderstorm activity well east of Matthew's core...and therefore some heavy rainfall with flash flooding potential will be possible over the Dominican Republic even though the winds will not be strong. Interests across the southeastern United States coast should monitor the progress of Matthew as its not clear how close to the coast Matthew will get after it emerges from the Bahamas.

...SPECIAL FEATURE...SURFACE LOW INVEST 98-L...
This special feature section is for area of interest #2 marked in the above atmospheric features chart.

Current Prognosis...The surface low triggered by divergence on the east side of the upper vortex that has been in the central Atlantic over the last few days has become better organized while reaching a belt of upper easterly winds on the north side of the upper vortex and south side of a western Atlantic upper anticyclone. This belt of upper winds is lined up with the mostly west track of the surface low seen in satellite animation which is keeping vertical shear favorably low...and with the west Atlantic upper anticyclone not yet de-amplifying into an upper ridge (which was expected due to cold air advection behind the intense 957 mb frontal cyclone in the north Atlantic) the belt of upper easteriles is expected to continue in the near-term and therefore tropical cyclone formation is possible. As of 0000Z the surface low was centered at 21.5N-55.8W...and twenty-four hours before that this system was at 57.5W which suggests a nearly 3.5W per 24-hour progression. Satellite animation also suggests about a 1W longitude per 6 hour (or basically 4W per 24 hour) rate...and so the track forecast below is intially based on a 3.5W to 4W rate.

Atmospheric Outlook for the Forecast Period...The track is expected to bend increasingly northward...likely toward Bermuda...as this system moves into the western Atlantic while getting pulled into the low-level ridge weakness generated by the deep-layered 1014 mb frontal cyclonic system currently over the eastern United States. By the end of the forecast period...what is left of the northern upper-level of the frontal cyclonic system will have moved into the northwest Atlantic as a shortwave upper trough...with the eastern divergence of the shortwave producing a frontal depression to the northeast that will likely pull this system northeastward by the end of the 120 hour forecast period. On the forecast track...this system will initially be embedded in the belt of favorable upper easterlies mentioned in the above current prognosis which could allow for tropical cyclone formation. But after 24 hours...this system will become sheared by upper northerlies on the east side of Hurricane Matthew's anticyclonic outflow and so the forecast shows this system staying a weak tropical cyclone thru the forecast period.

Thermodynamic Outlook for the Forecast Period...On the forecast track...this system will be over 28 to 30 deg C waters supportive for tropical development.

24 Hr Forecast (0000Z Oct 4)...35 mph maximum sustained wind tropical depression centered at 22N-59.5W

48 Hr Forecast (0000Z Oct 5)...35 mph maximum sustained wind tropical depression under northerly vertical shear centered at 24N-62.5W

72 Hr Forecast (0000Z Oct 6)...35 mph maximum sustained wind tropical depression under northerly vertical shear centered at 26.5N-65W

96 Hr Forecast (0000Z Oct 7)...35 mph maximum sustained wind tropical depression under northerly vertical shear centered just southwest of Bermuda at 29.5W-66W

120 Hr Forecast (0000Z Oct 8)...35 mph maximum sustained wind tropical depression under northerly vertical shear centered just east of Bermuda at 32.5N-63.5W

2016 Atlantic Hurricane Season Birdseye Discussion #135

By: NCHurricane2009, 5:32 AM GMT on October 02, 2016

...SUNDAY OCTOBER 2 2016 1:35 AM EDT...
Alert! Intense Hurricane Matthew wobbles and then begins a northward track at a more east location...now placing Haiti and the eastern Bahamas at risk for strong damaging winds from Matthew. Interests in these locations should rush preparations to completion this weekend. In addition the slight change in track places the Dominican Republic at risk for heavy rain with flooding potential. Meanwhile interests in Jamaica...eastern Cuba...and the central and western Bahamas should continue executing preparations. Interests across the southeastern United States coast should monitor the progress of Matthew as it is not yet clear how close to the coast the hurricane will track after it emerges from the Bahamas. See first special feature section below for additional details. Visit www.nhc.noaa.gov for up to the minute latest information on Matthew...including all hurricane and tropical storm watches and warnings.

In addition to Matthew...see the following statements for two other areas of interest...

The following statement concerns area of interest #1 marked over the eastern tropical Atlantic in the atmospheric features chart below. The tropical wave that emerged from Africa yesterday is passing by the Republic of Cabo Verde while producing disorganized thunderstorms to the south and southwest of the islands. Additional development of this tropical wave is possible over the next few days as a more favorable upper ridge has developed to the southeast of the weakening and retrograding upper vortex in the central tropical Atlantic and over this tropical wave. Therefore will continue to monitor this tropical wave.

The following statement concerns area of interest #2 marked over the central tropical Atlantic in the atmospheric features chart below. While one of the two tropical waves in the central tropical Atlantic mentioned in discussion #132 dissipated...the other has interacted with the divergence on the southeast side of the the upper vortex that has persisted in the central Atlantic...resulting in a tropical disturbance with an extensive area of showers and thunderstorms. The remaining tropical wave is moving westward and away while a 1010 mb surface low near 17.5N-52.5W has developed in this thunderstorm activity. This surface low is expected to track increasingly northward into the western Atlantic...perhaps toward Bermuda...in the next few days while pulled into the low-level ridge weakness generated by the deep-layered 1015 mb frontal cyclonic system currently over the eastern United States. There is a nearby belt of easterly upper-level winds north of the upper vortex and south of a west Atlantic warm core upper anticyclone that is in alignment with the surface low's track and thus would keep vertical shear low. However these easterly upper winds are expected to change and possibly reverse into a shearing direction as the west Atlantic upper anticyclone de-amplifies into an upper ridge due to cold air advection on the back side of the strong 972 mb frontal cyclone in the north Atlantic. In addition this system will later track into unfavorable northerly wind shear and upper convergence on the east side of Matthew's anticyclonic upper outflow. Therefore tropical cyclone formation from this system is not likely.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1928Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...MAJOR HURRICANE MATTHEW...
Current Prognosis...Finally the rapid intensification episode of Matthew has stopped and the hurricane has actually weakened back to category 4 with 150 mph maximum sustained winds. Satellite showed the pinhole eye become crumpled...suggesting that maybe an eye wall replacement cycle was the reason for the weakening. However the pinhole eye has regained its earlier sharper and circular appearance and the current 150 mph maximum sustained wind intensity is a little higher than the earlier 140 mph minimum from this past afternoon. The current central pressure of 940 mb is lower than last night's 941 mb when Matthew was a stronger category 5...suggesting the hurricane might have grown a little bit larger and broader such that the surface pressure gradient and winds are lower for the same/lower central pressure. Satellite confirms this with Matthew's thunderstorm field being larger than 24 hours ago. The hurricane continues to have its signature circular core with central pinhole eye...with comma shaped storm mass wrapped around the core to the east. After stalling and then wobbling in a counter-clockwise loop...the eye is now moving north-northwest to northwest and passed over 13.5N-73.4W as of 0000Z earlier this evening.

Atmospheric Outlook for the Forecast Period...The westward-retrograding cut-off upper vortex in the central Atlantic has continued to push the upper anticyclone over and east of Matthew in a westward direction. In addition Matthew has slowed down and has begun a more northward track due to the deep-layered 1015 mb frontal cyclone currently over the eastern United States. This is allowing the upper anticyclone to catch up and become vertically stacked with Matthew...potentially allowing Matthew to re-strengthen and perhaps reach even higher strength than before while taking advantage of the anticyclone's low shear and enhanced upper outflow. The northward track is expected to become increasingly faster in the next 72 hours as the distance between Matthew and the steering southern fracture upper trough to be left behind by the deep-layered frontal cyclone decreases. By 96 to 120 hours...the southern fracture upper trough is forecast to dissipate...with the strong surface ridge currently building behind the frontal cyclone increasingly slowing the northward progress while simultaneously bending the the track more westward. However a sharp bend to the west is not expected as the northern upper-level part of the deep-layered frontal cyclone will have shifted into the northwest Atlantic as a shortwave upper trough whose eastern divergence will drop surface pressures to the northeast of Matthew. This drop in surface pressures would try to pull Matthew eastward...which is why the westward lean in track at 96 to 120 is not a sharp westward lean.

Thermodynamic Outlook for the Forecast Period...Matthew will be passing over rather favorable 30 to 31 deg C waters in the Caribbean and over the Bahamas in the next 96 hours. By 120 hours the hurricane will be reaching slightly less warm 29 deg C waters.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 3)...175 mph maximum sustained wind hurricane south-southwest of Haiti at 15N-74.5W

48 Hr Forecast (0000Z Oct 4)...160 mph maximum sustained wind hurricane centered just southwest of Haiti at 17.5N-75W

72 Hr Forecast (0000Z Oct 5)...140 mph maximum sustained wind hurricane moving into the eastern Bahamas at 22.1N-75W

96 Hr Forecast (0000Z Oct 6)...150 mph maximum sustained wind hurricane over the central and western Bahamas...centered at 25.1N-76.5W

120 Hr Forecast (0000Z Oct 7)...150 mph maximum sustained wind hurricane centered just north of the western Bahamas at 27.5N-77.5W

Track Forecast...Matthew is slightly east of my previous forecast based on the 0000Z center fix in the above current prognosis section. Therefore I have slighlty adjusted my forecast track eastward accordingly.

Intensity Forecast...My intensity forecast shows Matthew re-strengthening into a category 5 hurricane stronger than its previous category 5 peak due to the improving satellite appearance of the core noted in the above current prognosis...and due to atmospheric conditions becoming even more favorable as the upper anticyclone approaching from the east becomes perfectly stacked with the hurricane per the above atmospheric outlook section. I have slightly raised the intensity forecast for 0000Z October 4 and 0000Z October 5 as the eastward adjusted track decreases the land interaction...with the eye now more likely to pass between Jamaica and Haiti instead of over Jamaica...and with the eye crossing a narrower section of eastern Cuba. However weakening is still shown during this timeframe due to the likelihood of land interaction. Some re-strengthening is still shown at the end of the forecast period as Matthew clears land...but at this time I am not showing category 5 intensity for the end of the forecast period as Matthew moves into slightly less oceanic heat content per the above thermodynamic outlook section.

Impact Forecast...Impact swath is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track. The eastward adjusted track now puts Haiti and the eastern Bahamas in play for dangerous damaging winds...and so preparations in these areas should be rushed to completion this weekend. The adjusted track also puts the Dominican Republic in play for flash flooding potential from Matthew's eastern rain bands. Interests in Jamaica...eastern Cuba...and the central and western Bahamas should also continue executing preparations for a severe strike from an intense Hurricane Matthew.

2016 Atlantic Hurricane Season Birdseye Discussion #134

By: NCHurricane2009, 6:43 AM GMT on October 01, 2016

...SATURDAY OCTOBER 1 2016 2:45 AM EDT...
Alert! Interests in Jamaica...eastern Cuba...and Bahamas should execute preparations this weekend for early next week...for severe weather (highly damaging winds and flooding) from a major hurriane of extrodinary strength. Matthew has continued to rapidly strengthen and is now the first category 5 hurricane in the Atlantic basin since Felix in 2007. With conditions remaining highly favorable for Matthew...the hurricane could strengthen even further above its current low-end category 5 strength. See first special feature section below for additional details. Visit www.nhc.noaa.gov for up to the minute latest information on Matthew...including all hurricane and tropical storm watches and warnings.

In addition to Matthew...see the following statements for two other areas of interest...

The following statement concerns area of interest #1 marked over the eastern tropical Atlantic in the atmospheric features chart below. The vigorous tropical wave west of the Republic of Cabo Verde has become less organized and has lost all significant thunderstorm activity. Its possible that this tropical wave will become unfavorably sheared by the westward-retrograding large upper vortex in the central tropical Atlantic instead of taking advantage of more favorable upper ridging building to the southeast of the upper vortex. This is my final statement on this feature on this blog unless it later shows signs of development.

The following statement concerns area of interest #2 marked over the eastern tropical Atlantic in the atmospheric features chart below. Satellite pictures suggest there is another tropical wave that has recently emerged from Africa and is currenlty east of the Republic of Cabo Verde. So far the tropical wave has become less organized and has been losing significant thunderstorm activity. However additional development of this tropical wave is possible over the next few days as a more favorable upper ridge has developed to the southeast of the weakening and retrograding upper vortex in the central tropical Atlantic and over this tropical wave. Therefore will continue to monitor this tropical wave.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1929Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).

...THERMODYNAMICS BIRDSEYE CHART...

This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...MAJOR HURRICANE MATTHEW...
Current Prognosis...Matthew has become the first category 5 hurricane in the Atlantic basin since Felix in 2007 while continuing a very impressive rapid intensification episode. Nighttime infrared shows Matthew overall is a small to medium sized hurricane featuring a circular core of intense thunderstorms with a pinhole eye in the middle...and a comma shaped storm mass also with high intensity wrapped around the core to the north and east. As of 0000Z the eye packing 160 mph maximum sustained winds passed over 13.5N-72W.

Atmospheric Outlook for the Forecast Period...The westward-retrograding cut-off upper vortex in the central Atlantic has continued to push the upper anticyclone over Matthew in a westward direction. In addition Matthew will be slowing down and then bending northward in track during the forecast period in response to the deep-layered 1013 mb frontal cyclone currently over the eastern United States. This will allow the upper anticyclone to further catch up and become vertically stacked with Matthew...potentially allowing Matthew to strengthen even more or maintain its current low-end category 5 strength while taking advantage of the anticyclone's low shear and enhanced upper outflow. It should be noted the northward turn is expected to be initially very slow in the next 24 hours as it appears Matthew will be a bit too far south of the deep-layered frontal cyclonic system to be pulled in by it. But then the northward turn is made increasingly faster from 24 to 96 hours as Matthew is forecast to move closer to and get steered by a southern fracture upper trough to get left behind by the deep-layered frontal cyclonic system. By 120 hours...the southern fracture upper trough is forecast to dissipate...and with the strong surface ridge currently building behind the frontal cyclone slowing the northward progress while simultaneously increasing the westward component in the track. However a sharp turn to the west is unlikely as the northern upper-level part of the deep-layered frontal cyclone will have shifted into the northwest Atlantic as a shortwave upper trough whose eastern divergence will drop surface pressures to the northeast of Matthew. This drop in surface pressures would try to pull Matthew eastward...which is why the westward lean in track at 120 hours is not a sharp westward lean.

Thermodynamic Outlook for the Forecast Period...Matthew will be passing over rather favorable 30 to 31 deg C waters in the Caribbean in the next 72 hours...and then pass over favorable 30 to 31 deg C waters again after crossing Cuba and moving into the western Bahamas.


My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Oct 2)...175 mph maximum sustained wind hurricane in the central Caribbean Sea at 14N-74.5W

48 Hr Forecast (0000Z Oct 3)...175 mph maximum sustained wind hurricane southeast of Jamaica at 15.5N-75.5W

72 Hr Forecast (0000Z Oct 4)...155 mph maximum sustained wind hurricane centered over eastern Jamaica at 18N-76W

96 Hr Forecast (0000Z Oct 5)...135 mph maximum sustained wind hurricane moving into the western Bahamas at 22.6N-76W

120 Hr Forecast (0000Z Oct 6)...150 mph maximum sustained wind hurricane centered over the northwestern Bahamas at 25.6N-77.5W

Track Forecast...Matthew is slighlty east of my previous forecast based on the above 0000Z center fix. Therefore I have slighlty adjusted my forecast track eastward accordingly.

Intensity Forecast...While my previous forecast did predict Matthew to become category 5...this has occurred sooner and so I have no choice but to further increase the intensity forecast for the first 48 hours as conditions will become even more favorable for Matthew when the upper anticyclone approaching from the east becomes perfectly stacked with the hurricane per the above atmospheric outlook section. The intensity forecast for 72 to 96 hours is the same as the previous however...showing some weakening due to land interaction with Jamaica and eastern Cuba. I show some strengthening again at 120 hours due to the 30 to 31 deg C waters...due to reduced land interaction...and due to reduced chances that Matthew will get sheared by the southern fracture upper trough steering it as this upper trough is currently forecast to dissipate by that time.

Impact Forecast...Impact swath is an extrapolation of the 11 PM EDT NHC tropical storm wind field along my forecast track. Interests in Jamaica...eastern Cuba...and the central and western Bahamas should execute preparations this weekend for what is likely going to be a severe strike from an intense Hurricane Matthew early next week.


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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