NCHurricane2009's Blog

2016 Atlantic Hurricane Season Birdseye Discussion #52

By: NCHurricane2009, 3:38 AM GMT on June 30, 2016

...WEDNESDAY JUNE 29 2016 11:40 PM EDT...
The following statement concerns area of interest #1 marked in the northwestern Gulf of Mexico in the atmospheric features chart below. Upper divergence between westerlies on the south side of the longwave upper trough currently over the eastern United States and northerlies on the east side of an upper ridge extending from northern Mexico triggered showers and thunderstorms over the southeastern US which have since migrated southward over the past day...and a new surface trough has developed from this activity from south Georgia to the northwestern Gulf waters south of Louisiana. A portion of the Mexican upper ridge has overspread the tail end of the surface trough...with favorable outflow supplied by the upper ridge supporting a somewhat organized 1013 mb tropical low south of Louisiana this past afternoon and evening. As the longwave upper trough over the eastern US moves away...surface ridging will solidify to the north of the surface low over...which will push the surface low westward toward Texas in the next 72 hours. A shortwave upper trough (part of the longwave upper trough over the eastern US) is developing over northeast Texas and may move toward this system initially...which could cause less favorable upper winds. But then this shortwave is expected to evolve into a cut-off upper vortex that moves away into south Texas...so upper winds could then become more favorable for the later part of 72 hours...therefore will watch this surface low.

It remains quiet elsewhere in the Atlantic tropics.

...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 box 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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 #51

By: NCHurricane2009, 2:08 AM GMT on June 29, 2016

...TUESDAY JUNE 28 2016 10:08 PM EDT...
The Atlantic tropics remain quiet this evening...no tropical cyclone formation is expected in the near term.

...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 box 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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 #50

By: NCHurricane2009, 2:13 AM GMT on June 28, 2016

...MONDAY JUNE 27 2016 10:15 PM EDT...
The following statement concerns area of interest #1 over the southern Caribbean Sea...Nicaragua...and eastern Honduras marked in the atmospheric features chart below. Showers and thunderstorms in this region have increased over the last couple of days due to the development of an upper ridge between two cut-off upper vortices...one over the Bay of Campeche to the northwest...and the other to the northeast of the Bahamas. The upper ridge is supplying upper-level outflow...creating upper-level divergence needed for rising air and thunderstorms...and most recently a surface tropical wave passing through has further enhanced this activity. However this activity is largely expected to stay over land which will prevent tropical cyclone formation on the Atlantic (Caribbean) side. However this system could move into the eastern Pacific and develop there.

It is quiet elsewhere in the Atlantic tropics.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1919Z-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 box 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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 #49

By: NCHurricane2009, 12:19 AM GMT on June 27, 2016

...SUNDAY JUNE 26 2016 8:20 PM EDT...
The Atlantic tropics remain quiet with no tropical cyclone formation expected in the near term.

...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 circled by a yellow-dashed line are only mentioned on this blog post. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) 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 tropical weather outlook then it gets upgraded with a green-solid box 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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 #48

By: NCHurricane2009, 4:41 AM GMT on June 26, 2016

...SUNDAY JUNE 26 2016 12:45 AM EDT...
After an active start to the hurricane season...finally the Atlantic tropics are quiet with no tropical cyclone formation expected in the near term.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0132Z-released WPC analysis.

Areas of Interest circled by a yellow-dashed line are only mentioned on this blog post. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) 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 tropical weather outlook then it gets upgraded with a green-solid box 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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 #47

By: NCHurricane2009, 3:44 AM GMT on June 25, 2016

...FRIDAY JUNE 24 2016 11:46 PM EDT...
The following statement concerns Area of Interest #1 over the Bay of Campeche and western Gulf of Mexico marked in the atmospheric features chart below. The active tropical wave that was over the Yucatan peninsula of southeastern Mexico has moved into the western Gulf but has become poorly-organized. Therefore tropical cyclone formation is no longer expected from this tropical wave.

It is quiet elsewhere in the Atlantic tropics.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0129Z-released WPC analysis.

Areas of Interest circled by a yellow-dashed line are only mentioned on this blog post. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) 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 tropical weather outlook then it gets upgraded with a green-solid box 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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 #46

By: NCHurricane2009, 5:50 AM GMT on June 24, 2016

...FRIDAY JUNE 24 2016 1:50 AM EDT...
Continuing to watch an active tropical wave currently moving across the Yucatan peninsula of southeastern Mexico...see statement below...

The following statement concerns Area of Interest #1 over the Yucatan peninsula marked in the atmospheric features chart below. Showers and thunderstorms associated with a tropical wave remain well organized despite passage over land and thus tropical cyclone formation remains highly likely over the next 24 hours as it moves back over water across the Bay of Campeche. See special feature section below for additional details. Interests over the Bay of Campeche and east-central Mexico should monitor this system over the next couple of days.

...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 circled by a yellow-dashed line are only mentioned on this blog post. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) 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 tropical weather outlook then it gets upgraded with a green-solid box 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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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...YUCATAN TROPICAL WAVE INVEST 95-L...
This special feature section is for area of interest #1 marked in the above atmospheric features chart.

Current Prognosis...A tropical wave with a low pressure spin has moved across the Yucatan peninsula from the western Caribbean Sea for much of the past 24 hours. The thunderstorm activity has re-developed and remains organized despite passage over land...and therefore tropical cyclone formation remains likely as this system moves back over water across the Bay of Campeche over the next 24 hours. As of 0000Z...the tropical low pressure spin of this tropical wave was centered at 18N-90W. This is further west than my previous forecast...and therefore I have adjusted my forecast westward accordingly.

Atmospheric Outlook for the Forecast Period...An upper ridge over the southwestern United States (marked by blue H toward the top-left of the above atmospheric features chart) will remain in position during the forecast period...resulting in upper covergence on the southeast side of the upper ridge that will support surface ridging to the north of our tropical disturbance. Thus the surface ridging will continue to push the disturbance west-northwest across the Bay of Campeche...and eventually east-central Mexico. The cut-off upper vortex currently over eastern Mexico will continue to retrograde westward and away along the south side of the United States upper ridge...which will allow the favorable anticyclonic upper ridge overhead of the disturbance to remain coupled with this system. Thus atmospheric conditions will remain favorable during the forecast period.

Thermodynamic Outlook for the Forecast Period...Water temps in the Bay of Campeche are currently in the highly favorable 28 to 30 deg C range. Therefore thermodynamic conditions are expected to be rather favorable for tropical development.

24 Hr Forecast (0000Z Jun 25)...35 mph maximum sustained wind tropical depression centered over the Bay of Campeche at 19N-95W

48 Hr Forecast (0000Z Jun 26)...Remnant low over east-central Mexico centered at 20N-98.5W

2016 Atlantic Hurricane Season Birdseye Discussion #45

By: NCHurricane2009, 7:23 AM GMT on June 23, 2016

...THURSDAY JUNE 23 2016 3:25 AM EDT...
Continuing to watch an active tropical wave in the Caribbean as it moves into the western Caribbean this evening...see statement below...

The following statement concerns Area of Interest #1 over the western Caribbean Sea marked in the atmospheric features chart below. Showers and thunderstorms associated with a tropical wave that has moved from the central to western Caribbean have become better organized and thus tropical cyclone formation remains possible with this system. See special feature section below for additional details. Interests over the Yucatan peninsula...Bay of Campeche...and east-central Mexico should monitor this system over 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 1930Z-released WPC analysis.

Areas of Interest circled by a yellow-dashed line are only mentioned on this blog post. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) 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 tropical weather outlook then it gets upgraded with a green-solid box 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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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...WESTERN CARIBBEAN TROPICAL WAVE...
This special feature section is for area of interest #1 marked in the above atmospheric features chart.

Current Prognosis...As of 0000Z earlier in the evening...showers and thunderstorms associated with the tropical wave currently in the western Caribbean Sea have organized into a tropical low pressure spin which was centered at 17N-83.5W based on satellite imagery. This developing tropical low was centered at approximately 83W 6 hours earlier at 1800Z...suggesting a 6-hourly motion of 0.5W (or roughly 2 to 3 degrees west longitude per 24 hours). Currently shower and thunderstorm activity has weakened but there remains a well-defined cloud swirl. With warm western Caribbean waters...low shear and good upper outflow supplied by a fully-developed overhead anticyclonic upper ridge...it is possible thunderstorm activity redevelops and a tropical cyclone forms in the next 24 hours as this system moves toward the Yucatan peninsula which is what my forecast below currently shows.

Atmospheric Outlook for the Forecast Period...An upper ridge over the southern United States (marked by blue H and blue-zig-zag line in the above atmospheric features chart) will remain in position during the forecast period...resulting in upper covergence on the southeast side of the upper ridge that will support surface ridging to the north of our tropical disturbance. Thus the surface ridging will continue to push the disturbance west-northwest across the Yucatan peninsula...Bay of Campeche...and eventually east-central Mexico (the forecast track shown below is based on a 3W longitude per 24 hr pace which was observed in the above current prognosis section). The cut-off upper vortex currently over the Bay of Campeche will continue to retrograde westward and away along the south side of the United States upper ridge...which will allow the favorable anticyclonic upper ridge overhead of the disturbance to remain coupled with this system. Thus atmospheric conditions will remain favorable during the forecast period.

Thermodynamic Outlook for the Forecast Period...Water temps in the western Caribbean Sea and Bay of Campeche are currently in the highly favorable 29 to 30 deg C range. Therefore thermodynamic conditions are expected to be rather favorable for tropical development.

24 Hr Forecast (0000Z Jun 24)...35 mph maximum sustained wind tropical depression approaching the Yucatan peninsula...centered at 18N-86.5W

48 Hr Forecast (0000Z Jun 25)...Tropical low centered over the west-central Yucatan Peninsula at 19N-89.5W

72 Hr Forecast (0000Z Jun 26)...35 mph maximum sustained wind tropical depression centered over the eastern Bay of Campeche at 20N-92.5W

96 Hr Forecast (0000Z Jun 27)...45 mph maximum sustained wind tropical storm approaching east-central Mexico at 21N-95.5W

120 Hr Forecast (0000Z Jun 28)...Remnant low over east-central Mexico centered at 22N-98.5W

2016 Atlantic Hurricane Season Birdseye Discussion #44

By: NCHurricane2009, 3:07 AM GMT on June 22, 2016

...TUESDAY JUNE 21 2016 11:08 PM EDT...
Danielle dissipates over south-central Mexico...but another disturbance has the potential to develop while heading towards the Bay of Campeche and Mexico over the next few days. See the following statement for more details:

The following statement concerns Area of Interest #1 over the central Caribbean Sea marked in the atmospheric features chart below. The base of a western Atlantic upper trough has cut-off into an upper vortex currently over the northern Yucatan peninsula. Widespread upper divergence on the east side of this upper vortex continues to interact with the tropical wave that has recently emerged from the eastern Caribbean and into the central Caribbean...resulting in widespread shower and thunderstorm activity. The upper vortex will retrograde westward and away while moving around the south side of the strong United States upper ridge. Relatively higher pressures east of the upper vortex will promote favorable upper ridging that overspreads and moves westward with the tropical wave as the tropical wave moves across the Caribbean Sea and eventually toward the Yucatan peninsula of southeastern Mexico and Bay of Campeche over the next four days. Currently there is weak computer model support for this tropical wave...but should this system become better organized I will consider upgrading it to a special feature on this blog considering the favorable upper wind forecast.

...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 circled by a yellow-dashed line are only mentioned on this blog post. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) 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 tropical weather outlook then it gets upgraded with a green-solid box 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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 #43

By: NCHurricane2009, 4:23 AM GMT on June 21, 2016

...TUESDAY JUNE 21 2016 12:24 AM EDT...
Tropical depression four strengthens to Tropical Storm Danielle just before making landfall in east-central Mexico...becoming the earliest fourth named tropical storm in the Atlantic basin on record as the rather active start to the 2016 Atlantic Hurricane Season continues. Recently Danielle has weakened to a tropical depression and will soon dissipate into a remnant low...but will bring additional heavy rainfall with flash flooding potential across east-central Mexico spreading into south-central Mexico over the next 24 hours.

Also see statement below for an additional area of interest:

The following statement concerns Area of Interest #1 over the northeastern Caribbean Sea...Haiti...and the Dominican Republic. While interacting with the eastern upper divergence on the base of a western Atlantic upper trough...the tropical wave that has crossed the Lesser Antilles and entered the eastern Caribbean Sea continues to produce widespread showers and thunderstorms which are currently over the northeastern Caribbean region. The base of the upper trough is already beginning to evolve into a cut-off upper vortex that will retrograde westward and away along the south side of the strong United States upper ridge. Relatively higher pressures east of the retrograding cut-off upper vortex will promote favorable upper ridging that overspreads and moves westward with the tropical wave as the tropical wave moves across the Caribbean Sea and eventually toward the Yucatan peninsula of southeastern Mexico and southwestern Gulf of Mexico. Therefore will watch this tropical wave over the next few days. Currently there is weak computer model support for this tropical wave...but should this system become better organized I will consider upgrading it to a special feature on this blog considering the favorable upper wind forecast.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1930Z-released WPC analysis.

Areas of Interest circled by a yellow-dashed line are only mentioned on this blog post. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) 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 tropical weather outlook then it gets upgraded with a green-solid box 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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 DEPRESSION DANIELLE...
Current Prognosis...Over the last 24 hours...tropical depression four strengthened to Tropical Storm Danielle as the favorable upper ridge that was lagging behind to the east became vertically aligned with the tropical cyclone...which reduced vertical shear and enhanced its upper outflow. Danielle is however already back down to tropical depression status after making landfall in east-central Mexico earlier this evening...but the tropical cyclone still has an impressive look on satellite with symmetrical distribution of spiral thunderstorm bands. As of 0000Z earlier this evening...the center of Danielle was located at 21.2N-97.4W.

Atmospheric Outlook for the Forecast Period...Upper convergence on the northeast side of the upper ridge that moved over Danielle earlier today has begun building surface ridging over Mexico and immediately to the north of the storm. It was previously speculated that Danielle would slow down after landfall while getting stuck to the east of this developing surface ridge...but instead nighttime infrared suggests that Danielle is accelerating southwestward on the south side of this surface ridge and toward south-central Mexico.

Thermodynamic Outlook for the Forecast Period...Water temps are no longer a factor in Danielle's strength as Danille has made landfall.


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

24 Hr Forecast (0000Z Jun 22)...Remnant low over south-central Mexico...centered at 20N-100.5W

Track Forecast...Even though Danielle is north of my previous forecast track...I have adjusted my forecast track both south and westward due to the southwestward acceleration noted in the above atmospheric outlook section.

Intensity Forecast...Danielle should weaken to a remnant low over Mexico in the next 24 hours.

Impact Forecast...Main impact is expected to be heavy rainfall with flash-flooding potential in east-central Mexico and south-central Mexico.

2016 Atlantic Hurricane Season Birdseye Discussion #42

By: NCHurricane2009, 3:23 AM GMT on June 20, 2016

...SUNDAY JUNE 19 2016 11:24 PM EDT...
Tropical depression four forms in the Bay of Campeche and could break the record for the earliest fourth named tropical storm of the season. This record is currently held by Tropical Storm Debby in 2012 which was named on June 23rd of that year. Heavy rainfall with flash flooding potential is expected to move into east-central Mexico in the next 24 hours. See special feature section below for additional details...and visit www.nhc.noaa.gov for up to the minute latest information on this tropical cyclone.

Also see the following statements below concerning two additional areas of interest:

The following statement concerns Area of Interest #1 marked in the atmospheric features chart below...currently located in the western Atlantic over and west of Bermuda. The 1016 mb frontal cyclone in this region remains elongated...and the supporting cut-off upper vortex developing in the region (marked by blue L to the left of this area of interest) is also elongated. Therefore this system will remain too elongated to consolidate into a subtropical cyclone. This is my final statement on this blog concerning this system.

The following statement concerns Area of Interest #2 over the Lesser Anttilles and eastern Caribbean Sea marked in the atmospheric features chart below. Showers and thunderstorms in this region have significantly increased as a tropical wave interacts with upper divergence on the east side of the base of the western Atlantic upper trough associated with the 1016 mb frontal cyclone near Bermuda. Over the next few days...the base of the upper trough will evolve into a cut-off upper vortex that retorgrades westward and away along the south side of the strong United States upper ridge. Relatively higher pressures east of the retrograding cut-off upper vortex will promote favorable upper ridging that overspreads and moves westward with the tropical wave as the tropical wave moves across the Caribbean Sea. Therefore will watch this tropical wave over the next few days. Currently none of the computer models forecast this wave to develop...but should this system become better organized I will consider upgrading it to a special feature on this blog considering the favorable upper wind forecast.

...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 circled by a yellow-dashed line are only mentioned on this blog post. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) 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 tropical weather outlook then it gets upgraded with a green-solid box 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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 DEPRESSION FOUR...
Current Prognosis...The tropical disturbance that was that was crossing the Bay of Campeche has been upgraded to the fourth tropical depression of the 2016 Atlantic Hurricane Season when aircraft reconaissance spotted a closed circulation. As of 0000Z earlier this evening...the center of the tropical depression was located at 20N-95W. Most of the thunderstorm activity is currently north...over...and east of the center...covering the Bay of Campeche...west-central Gulf of Mexico...and parts of southeastern Mexico and Guatemala.

Atmospheric Outlook for the Forecast Period...Upper convergence on the southeast side a large upper ridge which has developed across the United States is building surface ridging to the north of the tropical depression...which will keep the tropical depression moving west-northwestward such that it makes landfall in east-central Mexico in the next 24 hours. The western Caribbean upper ridge which was lagging behind to the east is beginning to quickly shift westward over the tropical depression. This is because the cut-off upper vortex over eastern Mexico has moved westward and away while moving around the south side of the strong United States upper ridge...and also because the base of the upper trough associated with the 1016 mb west Atlantic frontal depression had dug southward into the Caribbean and has pushed the upper ridge westward out of the Caribbean. As the upper ridge catches up to the tropical cyclone and reduces the shear over it and also enhances its upper outflow...it could strengthen to a minimal tropical storm as it makes landfall in east-central Mexico. After lanfall...some surface ridging could build over Mexico and slow the westward progress of the tropical cyclone's remnant. This surface ridge would be supported by upper convergence on the east side of the upper ridge overhead of the tropical cyclone...as the upper ridge's westward pace becomes faster than the remnants.

Thermodynamic Outlook for the Forecast Period...Water temps in the Bay of Campeche are currently in the highly favorable 30 deg C range. Therefore thermodynamic conditions are expected to be rather favorable for tropical development.


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

24 Hr Forecast (0000Z Jun 21)...40 mph maximum sustained wind tropical storm centered just inland over east-central Mexico at 20.8N-97.6W

48 Hr Forecast (0000Z Jun 22)...Remnant low over east-central Mexico...centered at 21.5N-99W

Track Forecast...Once again...this system is located further west when compared to my previous forecast...so I have adjusted the forecast slightly westward accordingly. The system is also further south...so I have also made a slight southward adjustment to my forecast.

Intensity Forecast...Although atmospheric conditions are expected to become more favorable in the next 24 hours (as the upper ridge to the east shifts overhead per the above atmospheric outlook)...and although thermodynamic conditions are rather favorable with 30 deg C waters...not expecting this system to strengthen beyond a minimal tropical storm due to landfall expected within 24 hours.

Impact Forecast...Main impact is expected to be heavy rainfall with flash-flooding potential in east-central Mexico.

2016 Atlantic Hurricane Season Birdseye Discussion #41

By: NCHurricane2009, 4:22 AM GMT on June 19, 2016

...SUNDAY JUNE 19 2016 12:22 AM EDT...
The two areas of interest in the Atlantic tropics...one moving into the Bay of Campeche and the other over the western Atlantic...look unimpressive tonight. However continuing to watch both areas. If either area develops...it is likely that the record for the earliest fourth named storm in the Atlantic basin will be broken. The record is currently held by Tropical Storm Debby in 2012 which was named on June 23rd of that year.

The following statement concerns Area of Interest #1 marked in the atmospheric features chart below...currently located in the western Atlantic between the east coast of the United States and Bermuda. The 1011 mb frontal cyclone in this region remains elongated as noted in the first special feature section below. The latest model runs suggest the cut-off upper vortex to develop in the region will be elongated in nature and therefore this system may remain too elongated and never consolidate into a subtropical cyclone. Will watch the evolution of this system in the next 24 hours...and if it indeed remains elongated I will cancel it as a special feature on this blog. Additionally...the most reliable computer models (GFS and Euro) have converged on a more eastward track with this system such that it is likely to provide Bermuda with some weather over the next 24 hours...and then is likely to stay offshore of the northeastern United States. See first special feature section below for more information on this system.

The following statement concerns Area of Interest #2 over the Yucatan peninsula and Bay of Campeche marked in the atmospheric features chart below. The disturbed weather in this region supported by a tropical wave and favorable upper ridge has organized into a tropical low pressure spin...and the formation of a tropical depression or weak tropical storm is possible in the next 48 hours after which time it will make landfall in east-central Mexico with potential for some flash flooding heavy rainfall. See second special feature section below for additional details.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1943Z-released WPC analysis.

Areas of Interest circled by a yellow-dashed line are only mentioned on this blog post. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) 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 tropical weather outlook then it gets upgraded with a green-solid box 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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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...WESTERN ATLANTIC FRONTAL CYCLONE...
This special feature section is for area of interest #1 marked in the above atmospheric features chart.

Current Prognosis...A surface 1011 mb frontal cyclone is centered in the western Atlantic between Bermuda and the east United States coast at 31N-71W. The rotation and associated showers and thunderstorms are in a rather elongated southwest-northeast orientation due to the lengthy area of upper divergence on the east side of the supporting upper trough which is supporting a stretched area of low surface pressures.

Atmospheric Outlook for the Forecast Period...The supporting upper trough is expected to evolve into a cold core cut-off upper vortex ahead of the large upper ridge that has developed across the United States. The more reliable GFS and Euro (ECMWF) models have converged on a more eastward position for the forecast cut-off upper vortex...and therefore I have shifted the forecast track eastward accordingly. There remains potential that the surface frontal cyclone will whirl into a position beneath the cut-off upper vortex and transition into a subtropical cyclone in the next 48 hours. Just after that time...a large upper trough and surface frontal cyclone will have dived southeastward into eastern Canada and pull the forecast subtropical system northward. The upper vortex of the subtropical system is expected to open into an upper trough in the southwesterly flow ahead of this large upper trough...which should quickly increase the vertical shear and weaken the subtropical system by 72 hours. Shortly after that time...the remnants of the subtropical system is likely to become absorbed by the cold front of the frontal cyclone from eastern Canada.

Thermodynamic Outlook for the Forecast Period...With the forecast track shown below...this system will reach less favorable waters below 26 deg C in the next 24 hours...but by 48 hours approach the band of warm Gulf stream waters above 26 deg C...which combined with the cold temps of the overhead cut-off upper vortex could support instability for thunderstorm development and subtropical development.

24 Hr Forecast (0000Z Jun 20)...Frontal cyclone acquiring subtropical characteristics just west of Bermuda...centered at 32.5N-68W

48 Hr Forecast (0000Z Jun 21)...45 mph maximum sustained wind subtropical storm in the western Atlantic centered at 35N-70W

72 Hr Forecast (0000Z Jun 22)...Sheared remnant low centered offshore of Massachusetts at 40N-67.5W

...SPECIAL FEATURE...YUCATAN AND GULF OF MEXICO TROPICAL DISTURBANCE INVEST 94-L...
This special feature section is for area of interest #2 marked in the above atmospheric features chart.

Current Prognosis...The tropical disturbance that was crossing the Caribbean and Yucatan peninsula has emerged into the eastern Bay of Campeche with a low pressure spin...which was centered at 20.2N-92W as of 0000Z early this evening using visible and infrared satellite imagery. This is further northwest than where I expected the disturbance to consolidate...resulting in exposure to southwesterly vertical shear on the northwest side of western Caribbean upper ridging. I have adjusted my forecast track more north and west accordingly. The shear is keeping the thickest clouds biased to the east of the circulation center...and the disturbance has only managed to produce intermittent bursts and bands of thunderstorms within this cloudiness which keeps the satellite apperance overall poorly-organized.

Atmospheric Outlook for the Forecast Period...Upper convergence on the back side of the upper trough associated with the 1011 mb west Atlantic frontal depression and on the southeast side a large upper ridge which has developed across the United States is building surface ridging to the north of our tropical disturbance which will keep the disturbance moving west-northwestward across the Bay of Campeche and into east-central Mexico over the next 72 hours. The western Caribbean upper ridge which is currently lagging behind to the east of the tropical disturbance will quickly shift westward over the disturbance during the forecast period. This is because the cut-off upper vortex over eastern Mexico will shift westward and away while moving around the south side of the strong United States upper ridge...and also because the base of the upper trough associated with the 1011 mb west Atlantic frontal depression will also amplify southward into the Caribbean and push the upper ridge westward out of the Caribbean. Therefore as the upper ridge catches up to the disturbance and reduces the shear over it and also enhances its upper outflow...conditions will become more favorable for development. However I have lowered my intensity forecast tonight due to the currently poor satellite apperance of the disturbance and the fact that the disturbance continues to be further west than previously forecasted which will give it less time over water if this keeps occuring. At the end of the forecast period...some surface ridging could build over Mexico and slow the westward progress of the disturbance as it makes landfall in east-central Mexico. This surface ridge would be supported by upper convergence on the east side of the upper ridge overhead of the disturbance...as the upper ridge's westward pace becomes faster than the disturbance's.

Thermodynamic Outlook for the Forecast Period...Water temps in the Bay of Campeche are currently in the highly favorable 30 deg C range. Therefore thermodynamic conditions are expected to be rather favorable for tropical development.

24 Hr Forecast (0000Z Jun 20)...Tropical low centered over Bay of Campeche at 20.8N-94.2W

48 Hr Forecast (0000Z Jun 21)...40 mph maximum sustained wind tropical storm approaching landfall on the east coast of Mexico...centered at 21.5N-96.8W

72 Hr Forecast (0000Z Jun 22)...Remnant low located not far inland over east-central Mexico...centered at 22N-98.2W

2016 Atlantic Hurricane Season Birdseye Discussion #40

By: NCHurricane2009, 3:20 AM GMT on June 18, 2016

...FRIDAY JUNE 17 2016 11:21 PM EDT...
Still watching two areas in the Atlantic basin which could develop into tropical or subtropical cyclones. If either area develops...it is likely that the record for the earliest fourth named storm in the Atlantic basin will be broken. The record is currently held by Tropical Storm Debby in 2012 which was named on June 23rd of that year.

The following statement concerns Area of Interest #1 marked in the atmospheric features chart below...currently located in the western Atlantic just east of North Carolina. Interests along the mid-Atlantic and northeastern United States shore should carefully monitor the progress of the 1005 mb frontal cyclone currently centered just south of Cape Hatteras North Carolina as it could transition into a subtropical storm located just offshore in the next 72 hours. While some surf and rip currents are expected along the shoreline...most likely this system will be making landfall as a weakening remnant by 96 hours (4 days). See first special feature section below for additional details.

The following statement concerns Area of Interest #2 over the western Caribbean Sea and Yucatan Peninsula marked in the atmospheric features chart below. Disturbed weather supported by a tropical wave and favorable upper ridge in the region continues. This area of disturbed weather is expected to track west-northwestward into the Bay of Campeche in the southwestern Gulf of Mexico. Although the current land interaction as it crosses the Yucatan peninsula could become a limiting factor for tropical development of this system...interests in the Bay of Campeche should pay careful attention as the waters in this region are rather warm and upper wind forecasts remain favorable. See second special feature section below for additional details.

...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 circled by a yellow-dashed line are only mentioned on this blog post. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) 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 tropical weather outlook then it gets upgraded with a green-solid box 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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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...FRONTAL CYCLONE NEAR NORTH CAROLINA COAST...
This special feature section is for area of interest #1 marked in the above atmospheric features chart.

Current Prognosis...A classical summertime surface frontal cyclone supported by a shortwave upper trough has recently moved offshore from North Carolina...and is currently centered just south of Cape Hatteras at 34N-75w. As of the present time its cold front is draped across the southeastern United States where some strong to severe thunderstorms are occurring. Meanwhile current activity near the center of the frontal cyclone is weak and poorly-organized.

Atmospheric Outlook for the Forecast Period...While steered in the northwesterly flow on the back side of the 998 mb northwestern Atlantic deep-layered frontal cyclone and out ahead of a developing western US upper ridge...the frontal cyclone and its shortwave upper trough will continue southeastward into the western Atlantic over the next 24 hours. Much of the associated shortwave upper trough is expected to evolve into a cold core cut-off upper vortex ahead of the western US upper ridge by 48 to 72 hours. Two of the three models that have been consistently forecasting this system to develop (the CMC and GFS) have shifted more westward with the forecast position of the cut-off upper vortex...and therefore I have adjusted my forecast track westward accordingly. Meanwhile all three models that have been consistently showing this system develop (CMC...Euro...and GFS) show the system diving further to the south over the next 24 hours...and therefore all my forecast positions have been adjusted southward accordingly. I still forecast that the surface frontal cyclone will whirl into a position beneath the cut-off upper vortex and transition into a subtropical storm by 72 hours. Between 72 and 96 hours...a large upper trough and surface frontal cyclone is expected to dive southeastward into eastern Canada and pull the forecast subtropical cyclone northward. The upper vortex of the subtropical system is expected to open into an upper trough in the southwesterly flow ahead of this large upper trough...which should quickly increase the vertical shear and weaken the subtropical system by 96 hours. Shortly after that time...the remnants of the subtropical system is likely to move over Massachusetts and parts of the northeastern US while becoming absorbed by the cold front of the large frontal cyclone from eastern Canada.

Thermodynamic Outlook for the Forecast Period...With the forecast track shown below...this system will be over waters above 26 deg C for the next 24 hours which are supportive of subtropical to tropical development. But just after 48 hours the forecast track takes it into waters just below 26 deg C. However between 48 and 72 hours...the forecast track has this system move northwestward across the band of warm Gulf stream waters above 26 deg C...which combined with the cold temps of the overhead cut-off upper vortex could support enough instability for thunderstorm development and subsequent subtropical cyclone formation.

24 Hr Forecast (0000Z Jun 19)...Frontal cyclone centered in the western Atlantic offshore of the Carolinas at 30N-72W

48 Hr Forecast (0000Z Jun 20)...Frontal cyclone acquiring subtropical characteristics midway between the Carolinas and Bermuda...centered at 32.5N-70W

72 Hr Forecast (0000Z Jun 21)...50 mph maximum sustained wind subtropical storm centered just east of North Carolina at 34N-73W

96 Hr Forecast (0000Z Jun 22)...Sheared remnant low centered just south of Massachusetts at 39N-71.5W

...SPECIAL FEATURE...WESTERN CARIBBEAN AND YUCATAN PENINSULA DISTURBANCE...
This special feature section is for area of interest #2 marked in the above atmospheric features chart.

Current Prognosis...Over the last 24 hours...the most active portion of the disturbance has been over the western Yucatan peninsula where strong thunderstorms have been flaring while supported by divergence between the west side of Caribbean upper ridging and east side of weakening southern Gulf upper vorticity. The tropical wave in the area has quickly moved westward toward 90W longitude after being stationary...perhaps while getting attracted to surface pressure falls that might be occuring with the western Yucatan activity. However visible satellite imagery around sunset suggested that cyclonic turning was occuring in the clouds further east...along the eastern Yucatan shore at 88W longitude. Thus this is the longitude where I have initialized my forecast for this disturbance tonight...which is still further west than my previous forecast...and therefore I have adjusted my forecast westward accordingly. Because this system has made landfall over the Yucatan sooner before having the chance to develop a closed circulation...I have lowered my intensity forecast as well.

Atmospheric Outlook for the Forecast Period...This tropical disturbance is expected to interact with the 1005 mb frontal cyclone centered near Cape Hatteras North Carolina and its shortwave upper trough...as well as the large upper ridge building behind that feature over the western US. The shortwave upper trough is beginning to develop a southwest-northeast elongation....and its tail end is about to merge with what's left of the southern Gulf upper vorticity to create a cut-off upper vortex over eastern Mexco. Upper convergence on the back side of the upper trough and southeast side of the western US upper ridge will support widespread surface ridging to the north of our tropical disturbance which will accelerate it westward across the Bay of Campeche in the southwestern Gulf of Mexico. Despite the westward adjustment in my forecast track noted in the above current prognosis...the latest GFS computer model run still shows the upper ridge over the Caribbean moving westward with the tropical disturbance and staying aligned with it...which will protect the disturbance from shear and also favorably support upper-level outflow for it. The reason the Caribbean upper ridge will be able to shift westward with the disturbance is that the forecast cut-off upper vortex over eastern Mexico will shift westward and away while moving around the south side of the strong western US upper ridge. At the end of the forecast period...some surface ridging could build over Mexico and slow the westward progress of the disturbance as it makes landfall in east-central Mexico. This surface ridge would be supported by upper convergence on the east side of the upper ridge overhead of the disturbance...as the upper ridge's westward pace becomes faster than the disturbance's.

Thermodynamic Outlook for the Forecast Period...Water temps in the Bay of Campeche are currently in the highly favorable 30 deg C range. Therefore thermodynamic conditions are expected to be rather favorable for tropical development.

24 Hr Forecast (0000Z Jun 19)...Surface trough with cyclonic turning along west coast of Yucatan peninsula at 91W longitude.

48 Hr Forecast (0000Z Jun 20)...Tropical low centered over Bay of Campeche at 20N-93W

72 Hr Forecast (0000Z Jun 21)...45 mph maximum sustained wind tropical storm approaching landfall on the east coast of Mexico...centered at 21N-96W

96 Hr Forecast (0000Z Jun 22)...Remnant low located not far inland over east-central Mexico...centered at 21.5N-97.5W

2016 Atlantic Hurricane Season Birdseye Discussion #39

By: NCHurricane2009, 4:51 AM GMT on June 17, 2016

...FRIDAY JUNE 17 2016 12:52 AM EDT...
Continuing to watch two areas in the Atlantic basin which could develop into tropical or subtropical cyclones. If either area develops...it is likely that the record for the earliest fourth named storm in the Atlantic basin will be broken. The record is currently held by Tropical Storm Debby in 2012 which was named on June 23rd of that year.

The following statement concerns Area of Interest #1 over the Ohio Valley of the United States marked in the atmospheric features chart below. Interests along the northeastern United States shore should carefully monitor the progress of the Ohio Valley 1003 mb frontal cyclone and its shortwave upper trough over the next few days. As this system moves southeastward and offshore into warm enough waters...it could transition into a subtropical storm that will be located just offshore of the northeastern US by 96 hours (4 days). While some surf and rip currents will be possible along the shoreline...the current expectation is that this system will be making landfall as a weakening remnant by 120 hours (5 days). See first special feature section below for additional details.

The following statement concerns Area of Interest #2 over the western Caribbean Sea and Central America in the atmospheric features chart below. Disturbed weather supported by a tropical wave and favorable upper ridge in the region continues. This area of disturbed weather is expected to track west-northwestward toward the Bay of Campeche in the southwestern Gulf of Mexico. Although land interaction could become a limiting factor for tropical development of this system...interests in the Bay of Campeche should pay careful attention as the waters in this region are rather warm and the favorability of the upper wind forecasts have increased. See second special feature section below for additional details.

...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 circled by a yellow-dashed line are only mentioned on this blog post. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) 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 tropical weather outlook then it gets upgraded with a green-solid box 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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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...OHIO VALLEY FRONTAL CYCLONE...
This special feature section is for area of interest #1 marked in the above atmospheric features chart.

Current Prognosis...A classical summertime surface frontal cyclone supported by a shortwave upper trough was centered over the Ohio Valley region (specifically over northern West Virginia) at 39N-81w as of 0000Z. As of the present time this system is producing showers and thunderstorms (in a spiral wrapped around the cyclone center) over northeastern Ohio...southwestern Pennsylvania...eastern Maryland...and southern Virginia.

Atmospheric Outlook for the Forecast Period...While steered in the northwesterly flow on the back side of the 998 mb eastern Cananda/western Atlantic deep-layered frontal cyclone and out ahead of a western US upper ridge soon to develop...the frontal cyclone and its shortwave upper trough will eject southeastward into the western Atlantic waters by 24 hours. During this time the shortwave upper trough will have evolved into a southwest-northeast elongation ahead of the western US upper ridge...and then much of this upper trough is expected to evolve into a cold core cut-off upper vortex ahead of the upper ridge by 72 to 96 hours. Currently forecasting that the surface frontal cyclone will whirl into a position beneath the upper vortex and transition into a subtropical storm by 96 hours. Between 96 and 120 hours...a large upper trough and surface frontal cyclone is expected to dive southeastward into eastern Canada and pull the forecast subtropical cyclone northward. The upper vortex of the subtropical system is expected to open into an upper trough in the southwesterly flow ahead of this large upper trough...which should quickly increase the vertical shear and weaken the subtropical system by 120 hours. Shortly after that time...the remnants of the subtropical system is likely to move over Massachusetts and parts of the northeastern US while becoming absorbed by the cold front of the large frontal cyclone from eastern Canada.

Thermodynamic Outlook for the Forecast Period...With the forecast track shown below...this system will enter waters at or above 26 deg C by 24 hours which are supportive of subtropical to tropical development. But by 72 hours the forecast track takes it into waters just below 26 deg C. However between 72 and 96 hours...the forecast track has this system move northward across the band of warm Gulf stream waters above 26 deg C...which combined with the cold temps of the overhead cut-off upper vortex could support enough instability for thunderstorm development and subsequent subtropical cyclone formation.

24 Hr Forecast (0000Z Jun 18)...Frontal cyclone centered just offshore of North Carolina at 34N-74W

48 Hr Forecast (0000Z Jun 19)...Frontal cyclone centered in the western Atlantic offshore of the Carolinas at 32N-72W

72 Hr Forecast (0000Z Jun 20)...Frontal cyclone acquiring subtropical characteristics midway between the Carolinas and Bermuda...centered at 33.5N-70W

96 Hr Forecast (0000Z Jun 21)...50 mph maximum sustained wind subtropical storm centered offshore of the northeastern United States at 35.5N-71W

120 Hr Forecast (0000Z Jun 22)...Sheared remnant low centered just south of Massachusetts at 39.5N-71W

...SPECIAL FEATURE...WESTERN CARIBBEAN DISTURBANCE...
This special feature section is for area of interest #2 marked in the above atmospheric features chart.

Current Prognosis...Strong thunderstorm activity in the western Caribbean offshore of Nicaragua and Honduras...which was triggered by divergence between the west side of Caribbean upper ridging and southeast side of southern Gulf upper vorticity...continues to be the focus of this disturbance. Over the last 24 hours the latent heat release of these thunderstorms has helped enflame a western Caribbean anticyclonic center within the Caribbean upper ridging...and in turn the upper outflow of the anticyclonic center is re-enforcing the thunderstorms and surface pressure drops. The tropical wave in the area has become stationary at 85W longitude over the last day perhaps while attracted to the maximal drop in surface pressures. I have adjusted my forecast shown below a bit eastward as the area of low surface pressures appears focused more eastward toward the Caribbean upper ridging. Additional thunderstorm activity is over Nicaragua...Honduras...Guatemala...and western Yucatan peninsula. The activity over the western Yucatan maybe more supported by the divergence between the southern Gulf upper vorticity and Caribbean upper ridge instead of the anticyclonic outflow of the Caribbean upper ridge.

Atmospheric Outlook for the Forecast Period...This tropical disturbance is expected to interact with the 1003 mb frontal cyclone and its shortwave upper trough currently over the Ohio Valley and large upper ridge to build behind that feature from the western US. As the frontal cyclone moves offshore and potentially becomes a subtropical system...its associated upper trough is expected to have a southwest-northeast elongation whose tail end cuts-off into an upper vortex on the east coast of Mexico. Upper convergence on the back side of this upper trough and southeast side of the western US upper ridge will support widespread surface ridging to the north of our tropical disturbance which will accelerate it into the Bay of Campeche in the southwestern Gulf of Mexico. I have increased the intensity forecast for two reasons. First is that the disturbance has become focused at a more eastward position better aligned with the favorable Caribbean upper ridging as noted in the above current prognosis. Second is that the cut-off upper vortex over eastern Mexico should retrograde westward and away around the south side of the western US upper ridge...which will allow the Caribbean upper ridge to stay aligned with this disturbance. In fact the latest GFS computer model run shows the upper ridge on top of the disturbance instead of lagging behind to the southeast like shown yesterday...which will keep the vertical shear over this system low.

Thermodynamic Outlook for the Forecast Period...Water temps in the western Caribbean and Bay of Campeche are currently in the highly favorable 30 deg C range. Therefore thermodynamic conditions are expected to be rather favorable for tropical development.

24 Hr Forecast (0000Z Jun 18)...Weakening upper vorticity over the southern Gulf of Mexico with expanding anticyclonic upper ridge over the western Caribbean Sea. Surface tropical low centered at 17N-87W organizing beneath upper ridge.

48 Hr Forecast (0000Z Jun 19)...Surface tropical low just below tropical depression strength making landfall over northern Belize centered at 17.5N-88.5W

72 Hr Forecast (0000Z Jun 20)...Tropical low centered over southeastern Mexico at 18N-90W

96 Hr Forecast (0000Z Jun 21)...45 mph maximum sustained wind tropical storm in the Bay of Campeche centered at 19N-93W

120 Hr Forecast (0000Z Jun 22)...60 mph maximum sustained wind tropical storm approaching landfall on the east coast of Mexico...centered at 20N-96W

2016 Atlantic Hurricane Season Birdseye Discussion #38

By: NCHurricane2009, 4:26 AM GMT on June 16, 2016

...THURSDAY JUNE 16 2016 12:27 AM EDT...
Tonight...I have slightly changed the conventions of my atmospheric features birdseye chart to better highlight potential areas of interest. I now number areas of interest on the chart (#1, #2, etc) and use these numbers throughout the blog post to make it easier to match up statements in the blog with the visuals in the chart. As there are two current areas of interest...these changes are already in effect and hence already visible below. Feel free to provide feedback via comments on what you think of these changes or on the info provided on this blog overall.

The following statement concerns Area of Interest #1 over the north-central United States marked in the atmospheric features chart below. Interests along the northeastern United States shore should carefully monitor the progress of the north-central US 1006 mb frontal cyclone and its shortwave upper trough over the next few days. As this system moves southeastward and offshore into warm enough waters...it could transition into a subtropical storm that will be located just offshore of the northeastern US by 120 hours (5 days). See first special feature section below for additional details.

The following statement concerns Area of Interest #2 over the southern Caribbean Sea...Nicaragua...and Honduras marked in the atmospheric features chart below. Disturbed weather triggered by a tropical wave in this region has increased in concentration and intensity and is expected to track west-northwestward toward the Bay of Campeche in the southwestern Gulf of Mexico. Although land interaction and westerly vertical shear could become limiting factors for tropical development of this system...interests in the Bay of Campeche should pay careful attention as the waters in this region are rather warm...and any reduction in the shear or land interaction forecast could result in a rapidly developing tropical cyclone by 120 hours (5 days). See second special feature section below for additional details.

...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 circled by a yellow-dashed line are only mentioned on this blog post. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) 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 tropical weather outlook then it gets upgraded with a green-solid box 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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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...NORTH-CENTRAL UNITED STATES FRONTAL CYCLONE...
This special feature section is for area of interest #1 marked in the above atmospheric features chart.

Current Prognosis...As of earlier this evening...a classical summertime surface frontal cyclone supported by a shortwave upper trough was centered over northeastern Minnesota/northwestern Wisconsin near 46N-91W. As of the present time this system is producing showers and thunderstorms (some severe) over the Great Lakes region...Ohio and Tennesee Valley regions...and over a large area of the northeastern and mid-Atlantic United States.

Atmospheric Outlook for the Forecast Period...While steered in the northwesterly flow on the back side of the 998 mb eastern Cananda/western Atlantic deep-layered frontal cyclone and out ahead of a western US upper ridge soon to develop...the frontal cyclone and its shortwave upper trough will eject southeastward into the western Atlantic waters by 48 hours. During this time the shortwave upper trough will have evolved into a southwest-northeast elongation ahead of the western US upper ridge...and then much of this upper trough is expected to evolve into a cold core cut-off upper vortex ahead of the upper ridge by 96 to 120 hours. Currently forecasting that the surface frontal cyclone will whirl into a position beneath the upper vortex and transition into a subtropical storm.

Thermodynamic Outlook for the Forecast Period...With the forecast track shown below...this system will enter waters at or above 26 deg C at 48 hours which are supportive of subtropical to tropical development. But by 96 hours the forecast track takes it into waters just below 26 deg C. However between 96 and 120 hours...the forecast track has this system move northward across the band of warm Gulf stream waters above 26 deg C...which combined with the cold temps of the overhead cut-off upper vortex could support enough instability for thunderstorm development and subsequent subtropical cyclone formation.

24 Hr Forecast (0000Z Jun 17)...Frontal cyclone centered over Ohio/West Virginia at 40N-81W

48 Hr Forecast (0000Z Jun 18)...Frontal cyclone centered just offshore of Cape Hatteras North Carolina at 35N-74W

72 Hr Forecast (0000Z Jun 19)...Frontal cyclone centered in the western Atlantic offshore of the Carolinas at 32.5N-72W

96 Hr Forecast (0000Z Jun 20)...Frontal cyclone acquiring subtropical characteristics midway between the Carolinas and Bermuda...centered at 34N-70W

120 Hr Forecast (0000Z Jun 21)...50 mph maximum sustained wind subtropical storm centered offshore of the northeastern United States at 37N-70W

...SPECIAL FEATURE...SOUTHERN CARIBBEAN DISTURBANCE...
This special feature section is for area of interest #2 marked in the above atmospheric features chart.

Current Prognosis...A tropical wave has moved from the southern Caribbean at 80W longitude and into Nicaragua and Honduras at 85W longitude over the last 24 hours. While interacting with the upper divergence on the southeast side of the elongated upper vortex over the southern Gulf of Mexico and on the northwest side of the central Caribbean upper ridge...the tropical wave has produced a concentrated area of showers and thunderstorms that have moved into Nicaragua and Honduras. Recently the inland activity has weakened with a significant increase in offshore activity over the western Caribbean Sea...and if current trends continue this will increase the chances of tropical development. On a final note...it is now clear that our disturbance has consolidated around our western tropical wave at 85W...and the trailing and approaching tropical wave that has been moving across northern South America/SE Caribbean will not be playing much of a role. Therefore I have adjusted my forecast shown below westward.

Atmospheric Outlook for the Forecast Period...The first part of my updated forecast assumes that as the tropical wave at 85W exits...continued concentrated showers and thunderstorms supported by upper divergence between the southern Gulf upper vortex and Caribbean upper ridge will produce a seperate tropical surface trough/low over Honduras/western Caribbean Sea. During the later part of the forecast period (72 hrs and beyond)...interaction is expected with the 1006 mb frontal cyclone and its shortwave upper trough currently over the north-central US and large upper ridge to build behind that feature from the western US. As this system moves offshore and potentially becomes a subtropical system...its associated upper trough is expected to have a southwest-northeast elongation whose tail end cuts-off into a western Gulf of Mexico upper vortex. Upper convergence on the back side of this upper trough and southeast side of the western US upper ridge will support widespread surface ridging to the north of our tropical disturbance which will accelerate it into the Bay of Campeche in the southwestern Gulf of Mexico. I show a conservative intensity forecast due to land interaction and expected southwesterly vertical shear. The shear for the first 72 hours will be due positioning beneath southwesterly flow between the Caribbean upper ridge and southern Gulf upper vortex. By 96 and 120 hours...Gulf upper vorticity is expected to retrograde westward and away into Mexico due to the strength of the forecast western US upper ridge. This would allow the Caribbean upper ridge to move into the Bay of Campeche in the wake of the upper vorticity...but some unfavorable westerly shear is still possible by that time as the latest model runs suggest the Caribbean upper ridge will lag to the southeast of the forecast tropical cyclone.

Thermodynamic Outlook for the Forecast Period...Water temps in the Caribbean and Bay of Campeche are currently in the highly favorable 30 deg C range. Therefore thermodynamic conditions are expected to be rather favorable for tropical development.

24 Hr Forecast (0000Z Jun 17)...Elongated and weakening upper vorticity over the southern Gulf of Mexico. Upper ridge over western Caribbean Sea. Surface trough with concentrated showers and thunderstorms along 87W longitude in the western Caribbean Sea and over Honduras supported by upper divergence between the upper vorticity and upper ridge.

48 Hr Forecast (0000Z Jun 18)...Elongated and weakening upper vorticity over the southern Gulf of Mexico. Upper ridge over the western Caribbean Sea. Surface tropical low just below tropical depression strength (supported by divergence between the upper vorticity and upper ridge) making landfall in northern Belize centered at 17N-88.5W

72 Hr Forecast (0000Z Jun 19)...Remaining upper vorticity over the southern Gulf merges with tail end of upper trough associated with possible subtropical disturbance offshore of eastern US...resulting in a large upper vortex over western Gulf of Mexico. Upper ridge over the western Caribbean Sea and southeastern Mexico. Surface tropical low supported by divergence between the upper vorticity and upper ridge centered over southeastern Mexico at 17.8N-90W

96 Hr Forecast (0000Z Jun 20)...Tropical low centered just offshore of Mexico in the Bay of Campeche at 19N-92W

120 Hr Forecast (0000Z Jun 21)...40 mph maximum sustained wind tropical storm in the Bay of Campeche centered at 19.8N-94W

2016 Atlantic Hurricane Season Birdseye Discussion #37

By: NCHurricane2009, 4:57 AM GMT on June 15, 2016

...WEDNESDAY JUNE 15 2016 1:00 AM EDT...
The cold front of the deep-layered 997 mb frontal cyclone entering the western Atlantic from eastern Canada has been driven southward into the warmer western Atlantic waters. Warm air advection ahead of the currently developing north-central US 1001 mb frontal cyclone has also built some favorable upper ridging over the western Atlantic...but this upper ridging is largely south of the front and therefore no short-term tropical development is expected here. However the aforementioned 1001 mb frontal cyclone and its shortwave upper trough is expected to move southeastward along the front and offshore into the western Atlantic where it could subsequently acquire subtropical characteristics. Interests in the western Atlantic (including Bermuda and eastern United States shore) should monitor this situation carefully as there remains large uncertainty with this situation even though we are only as little as four days away (this low confidence has prevented me from upgrading this system to a special feature tonight). The Euro (ECMWF) model shows a non-tropical or perhaps subtropical system moving northward just offshore of the northeastern US...the GFS shows a possible subtropical system that moves westward back into the southeastern US coast...and the CMC computer model shows a non-tropical or perhaps subtropical system moving northward to the northeast of Bermuda.

Upper ridging has built into the western Atlantic due to warm air advection ahead of the 1001 mb frontal cyclone over the north-central US...and this upper ridge has cut-off the southern part of the 997 mb eastern Canada/western Atlantic deep-layered cyclone into an upper vortex over south Florida (soon to retrograde westward into the Gulf of Mexico). Relatively higher pressures to the southeast of this upper vortex has already started a favorable upper ridge over the southern Caribbean Sea that is more expansive due to the fact that the other upper vortex that was expected near the northeast Caribbean has not materialized. In addition...disturbed weather beneath the favorable southern Caribbean upper ridge has already started while supported by the surface convergence of a tropical wave passing through and outflow of the upper ridge. Many computer models continue to support the idea of tropical cyclone formation as this area of disturbed weather moves across Central America...the western Caribbean...and Bay of Campeche in the southwestern Gulf of Mexico. Therefore I have upgraded this disturbance to a special feature...see special feature section below for additional details on this situation.

...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.

Features boxed in green...if any...are mentioned in the National Hurricane Center (NHC) traditional 48-hour outlook and or are considered an "Invest" on the Naval Research Laboratory site of the US Navy at the time the chart was generated. I do not box features in green if they are only included in the NHC's longer term 5-day outlook.

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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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...SOUTHERN CARIBBEAN DISTURBANCE...
Current Prognosis...A tropical wave moving across the Caribbean Sea (located at 80W longitude as of 0000Z) has combined with the upper outflow of a developing southern Caribbean upper ridge to produce increasing shower and thunderstorm activity this past afternoon...although this activity has relaxed this evening. Many computer models continue to support the idea of tropical cyclone formation as this area of disturbed weather moves across Central America...the western Caribbean...and Bay of Campeche in the southwestern Gulf of Mexico. See the atmospheric outlook...thermodynamic outlook...and forecast below for details.

Atmospheric Outlook for the Forecast Period...The first part of the forecast period will consist of an upper ridge expanding from the southern Caribbean Sea as the current upper vorticity over south Florida and the southern Gulf of Mexico weakens. A pair of tropical waves (the one mentioned in the above current prognosis and the other approaching the southeastern Caribbean this evening) will interact with the favorable outflow of the upper ridge to produce showers and thunderstorms and ultimately a broad tropical low pressure spin that will take a while to consolidate...which is why my forecast below does not forecast tropical cyclone formation before 120 hours. The later part of the forecast period (96 hrs and beyond) features interaction with the 1001 mb frontal cyclone and its shortwave upper trough currently over the north-central US and large upper ridge to build behind that feature from the western US. As this system moves offshore and potentially becomes a subtropical system...its associated upper trough is expected to have a southwest-northeast elongation whose tail end cuts-off into a western Gulf of Mexico upper vortex. Upper convergence on the back side of this upper trough and southeast side of the western US upper ridge will support widespread surface ridging to the north of our tropical disturbance which will accelerate it into the Bay of Campeche in the southwestern Gulf of Mexico by 120 hours. Tropical cyclone formation in the Bay of Campeche is then likely after 120 hours as the unfavorable western Gulf cut-off upper vortex retrogrades westward out of the way and into Mexico (due to the large western US upper ridge).

Thermodynamic Outlook for the Forecast Period...Water temps in the Caribbean and Bay of Campeche are currently in the extremely favorable 29 to 30 deg C range. Therefore thermodynamic conditions are expected to be rather favorable for tropical development.

24 Hr Forecast (0000Z Jun 16)...Elongated upper vortex over the southern Gulf of Mexico. Expanding upper ridge over the central Caribbean. Tropical wave exiting the area from Central America...tropical wave approaching from the southeastern Caribbean. Showers and thunderstorms over the southern Caribbean.

48 Hr Forecast (0000Z Jun 17)...Elongated and weakening upper vorticity over the southern Gulf of Mexico. Expanding upper ridge centered southwest of Jamaica. Tropical wave exiting into the eastern Pacific from Central America...tropical wave approaching from northwestern South America. Low surface pressures across the southwestern half of the Caribbean with the greatest concentration of showers and thunderstorms over Central America and western Caribbean to the southwest of Jamaica.

72 Hr Forecast (0000Z Jun 18)...Elongated and weakening upper vorticity over the southern Gulf of Mexico. Expanding upper ridge over the western Caribbean. Low surface pressures across the southwestern half of the Caribbean with embedded tropical wave moving across the southern Caribbean. Greatest concentration of showers and thunderstorms over the western Caribbean and Central America.

96 Hr Forecast (0000Z Jun 19)...Showers and thunderstorms becoming better organized into a tropical low pressure spin underneath western Caribbean upper ridge...tropical wave over the southern Caribbean becoming absorbed by the tropical low. Remaining upper vorticity over the southern Gulf merges with tail end of upper trough associated with possible subtropical disturbance offshore of eastern US...resulting in a large upper vortex over western Gulf of Mexico.

120 Hr Forecast (0000Z Jun 20)...Western Caribbean tropical low and upper ridge crossing the Yucatan Peninsula of southeastern Mexico and into the Bay of Campeche of the southwestern Gulf of Mexico

2016 Atlantic Hurricane Season Birdseye Discussion #36

By: NCHurricane2009, 3:14 AM GMT on June 14, 2016

...MONDAY JUNE 13 2016 11:15 PM EDT...
The cold front of the deep-layered 992 mb frontal cyclone entering the western Atlantic from eastern Canada has been driven southward into the warmer western Atlantic waters. Warm air advection ahead of the currently developing central US frontal system is beginning to build favorable upper ridging over the cold front...and therefore will watch for possible tropical development along the cold front over the next few days. Currently the latest model runs suggest the most likely scenario for any tropical development along this front maybe more subtropical in nature...when a frontal cyclone and shortwave upper trough ejecting from the currently developing central US frontal system moves around the upper ridging and then dives southeastward along the cold front and enters the Atlantic in five days. Interests in the western Atlantic and east coast of the United States should monitor this situation carefully as there remains large uncertainty with this situation even though we are only as little as five days away. The Euro (ECMWF) model shows a non-tropical or perhaps subtropical system moving northward into the northeastern US coast...while the GFS shows a subtropical system that moves westward back into the southeastern US coast.

Warm air advection ahead of the currently developing central US frontal system is building upper ridging that is nosing into the western Atlantic that has already begun splitting off the southern part of the 992 mb eastern Canada/western Atlantic deep-layered cyclone two upper vorticity centers...one over south Florida (soon to retrograde westward into the Gulf of Mexico)...and another one about to form just north of the eastern Caribbean Sea. As these two cut-off upper vortices weaken...a favorable upper ridge will expand over the western Caribbean Sea in between. Computer model runs continue to suggest that a tropical wave could develop in about six days beneath such an upper ridge while moving across the western Caribbean Sea...southeastern Mexico...and Bay of Campeche in the southwestern Gulf of Mexico.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1925Z-released WPC analysis.

Features boxed in green...if any...are mentioned in the National Hurricane Center (NHC) traditional 48-hour outlook and or are considered an "Invest" on the Naval Research Laboratory site of the US Navy at the time the chart was generated. I do not box features in green if they are only included in the NHC's longer term 5-day outlook.

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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 #35

By: NCHurricane2009, 3:57 AM GMT on June 13, 2016

...SUNDAY JUNE 12 2016 11:57 PM EDT...
The shortwave upper trough and 996 mb frontal cyclone currently entering the western Atlantic from eastern Canada is amplifying. The cold front attached to the frontal cyclone will be driven southward into the warm western Atlantic waters during the current amplification. In addition...warm air advection ahead of the currently developing western US frontal system will build some favorable upper ridging over the cold front over the next few days. Therefore will watch for possible tropical development along the cold front during the next week. Currently the latest model runs suggest the most likely scenario for any tropical development along this front maybe more subtropical in nature...when a frontal cyclone and shortwave upper trough ejecting from the currently developing western US frontal system moves around the upper ridging and then dives southeastward along the cold front and transitions into a subtropical system offshore of the eastern United States next week.

Warm air advection ahead of the currently developing western US frontal system will build upper ridging to nose into the western Atlantic that will split off the southern part of the currently amplifying eastern North America/western Atlantic upper trough into two upper vorticity centers...one over the Gulf of Mexico...and another near the eastern Caribbean Sea. As these two cut-off upper vortices weaken...a favorable upper ridge will expand over the western Caribbean Sea in between. Computer model runs suggest that a tropical wave could develop next week beneath such an upper ridge while moving across the western Caribbean Sea...southeastern Mexico...and Bay of Campeche in the southwestern Gulf of Mexico.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1932Z-released WPC analysis.

Features boxed in green...if any...are mentioned in the National Hurricane Center (NHC) traditional 48-hour outlook and or are considered an "Invest" on the Naval Research Laboratory site of the US Navy at the time the chart was generated. I do not box features in green if they are only included in the NHC's longer term 5-day outlook.

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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 #34

By: NCHurricane2009, 3:21 AM GMT on June 12, 2016

...SATURDAY JUNE 11 2016 11:22 PM EDT...
The weak low pressure area over the northwestern Bahamas has degenerated into an east-west surface trough...the Atlantic tropics remain quiet for now.

The shortwave upper trough and 995 mb frontal cyclone currently over eastern Canada is expected to amplify while moving into the western Atlantic. The latest computer models suggest the cold front attached to the frontal cyclone will be driven southward into the warm western Atlantic waters during this amplification and perhaps tropically develop in a little over a week from now. It is too early to discuss the specifics for this situation given forecast skill this far out.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1932Z-released WPC analysis.

Features boxed in green...if any...are mentioned in the National Hurricane Center (NHC) traditional 48-hour outlook and or are considered an "Invest" on the Naval Research Laboratory site of the US Navy at the time the chart was generated. I do not box features in green if they are only included in the NHC's longer term 5-day outlook.

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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 #33

By: NCHurricane2009, 3:10 AM GMT on June 11, 2016

...FRIDAY JUNE 10 2016 11:11 PM EDT...
The weak low pressure area over the northwestern Bahamas currently has a central pressure of 1017 mb and has stalled while pinned to the south of the 1021 mb ridge over the eastern US. This feature only has 48 hours to tropically develop...after which time conditions will become hostile as a shortwave upper trough currently over central Canada (marked by blue-dashed line in the top-left of the atmospheric features chart below) amplifies and increases westerly vertical shear while moving into the western Atlantic.

The shortwave upper trough and 996 mb frontal cyclone currently over central Canada is expected to amplify while moving into the western Atlantic. The latest computer models suggest the tail end of the cold front attached to the frontal cyclone will be driven southward into the warm waters offshore of the southeastern United States during this amplification and perhaps tropically develop in a little over a week from now. It is too early to discuss the specifics for this situation given current forecast skill this far out.

...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.

Features boxed in green...if any...are mentioned in the National Hurricane Center (NHC) traditional 48-hour outlook and or are considered an "Invest" on the Naval Research Laboratory site of the US Navy at the time the chart was generated. I do not box features in green if they are only included in the NHC's longer term 5-day outlook.

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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 #32

By: NCHurricane2009, 1:24 AM GMT on June 10, 2016

...THURSDAY JUNE 9 2016 9:25 PM EDT...
Radar imagery from Florida and satellite imagery suggests the weak low pressure spin that was near western Cuba has moved northeastward across south Florida (while merging with the tail end of the cold front of the 988 mb frontal cyclone over eastern Canada)...and is now headed eastward to the northwestern Bahamas. This feature only has 72 hours to tropically develop...after which time conditions will become hostile as a shortwave upper trough currenlty over northwestern North America amplifies and increases westerly vertical shear while moving into the western Atlantic.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1930Z-released WPC analysis.

Features boxed in green...if any...are mentioned in the National Hurricane Center (NHC) traditional 48-hour outlook and or are considered an "Invest" on the Naval Research Laboratory site of the US Navy at the time the chart was generated. I do not box features in green if they are only included in the NHC's longer term 5-day outlook.

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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 #31

By: NCHurricane2009, 12:28 AM GMT on June 09, 2016

...WEDNESDAY JUNE 8 2016 8:28 PM EDT...
A surface trough with associated showers and thunderstorms continues to span the southeastern Gulf of Mexico and western Caribbean Sea while supported by upper-level outflow from an upper ridge that has persisted in the region (marked by blue H in the atmospheric features chart below). A spin along the surface trough appears to have developed near the western tip of Cuba...but the shower and thunderstorm activity has reduced. Will continue to watch for possible tropical development along this surface trough. Anything that develops is likely to move northeastward across Florida and the western Bahamas while initially pulled into the same ridge weakness that the remnant of Colin is in. Afterwards such a system would likely stall in the vicinity of the western Bahamas and waters offshore of the southeastern US while pinned to the south of the surface ridging currently developing over the central US (marked by red-zig-zag line in the top-left of the atmospheric features chart below). After 96 hours...conditions will then become hostile for any tropical system in this region after a shortwave upper trough from western North America amplifies and increases westerly vertical shear while moving into the western Atlantic.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1930Z-released WPC analysis.

Features boxed in green...if any...are mentioned in the National Hurricane Center (NHC) traditional 48-hour outlook and or are considered an "Invest" on the Naval Research Laboratory site of the US Navy at the time the chart was generated. I do not box features in green if they are only included in the NHC's longer term 5-day outlook.

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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 #30

By: NCHurricane2009, 12:42 AM GMT on June 08, 2016

...TUESDAY JUNE 7 2016 8:43 PM EDT...
Tropical Storm Colin has transtioned into a non-tropical remnant gale rapidly accelerating northeastward into the northwestern Atlantic from the southeasern United States. Therefore this is my final statement on this blog concerning Colin.

A surface trough with associated showers and thunderstorms spanning the southeastern Gulf of Mexico and western Caribbean Sea has developed in the wake of Colin...due to supportive upper-level outflow from favorable upper ridging that has persisted in the region (marked by blue H and blue-zig-zag line in the atmospheric features chart below). While missing the ridge weakness associated with Colin and the surface trough...tropical depression 1-E from the eastern Pacific is stalling as it makes landfall over southeastern Mexico and it appears 1-E will probably dissipate over land before having the opportunity to add to the disturbed weather associated with the surface trough. Will watch for possible tropical development along this surface trough...espeically as showers and thunderstorms are concentrated and a bit organized. Anything that develops from this surface trough is likely to move northeastward across Florida and the western Bahamas while initially pulled into the same ridge weakness that Colin is in. Afterwards such a system would likely stall in the vicinity of the western Bahamas and waters offshore of the southeastern US while pinned to the south of the surface ridging currently developing over the central US (marked by red-zig-zag line in the top-left of the atmospheric features chart below). After 120 hours...conditions will then become hostile for any tropical system in this region after a shortwave upper trough from the western US amplifies and increases westerly vertical shear while moving into the western Atlantic.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1923Z-released WPC analysis.

Features boxed in green...if any...are mentioned in the National Hurricane Center (NHC) traditional 48-hour outlook and or are considered an "Invest" on the Naval Research Laboratory site of the US Navy at the time the chart was generated. I do not box features in green if they are only included in the NHC's longer term 5-day outlook.

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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 #29

By: NCHurricane2009, 3:26 AM GMT on June 07, 2016

...MONDAY JUNE 6 2016 11:30 PM EDT...
Tropical Storm Colin about to make landfall in northern Florida...tropical storm force winds located southeast of the center to spread across the central Florida peninsula during the overnight hours...heavy rainfall expected for the remainder of the evening across parts of the southeastern United States. In the next 24 hours...Colin will transition into a non-tropical remnant gale while accelerating away from the southeastern United States and into the northwestern Atlantic Ocean. See special feature section below for more details on Colin. Visit www.nhc.noaa.gov for up to the minute latest information on Colin.

Tropical depression 1-E has developed in the eastern Pacific just to the south of southeastern Mexico from a tropical wave that entered the eastern Pacific from Central America on June 1st. The tropical depression will soon make landfall across southeastern Mexico and approach the southern Gulf of Mexico while getting pulled into a ridge weakness caused by Tropical Storm Colin...the persistent 1010 mb surface low in the western Gulf...and cold front of the 985 mb eastern North America frontal cyclone. The remnants of tropical depression 1-E may combine with the 1010 mb surface low in the western Gulf and aforementioned cold front to produce a surface trough across the Gulf of Mexico in the wake of Tropical Storm Colin. Will watch for potential tropical development along such a surface trough...esepcially as favorable upper ridging is expected to persist across the region. Currently no computer models show development.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1934Z-released WPC analysis.

Features boxed in green...if any...are mentioned in the National Hurricane Center (NHC) traditional 48-hour outlook and or are considered an "Invest" on the Naval Research Laboratory site of the US Navy at the time the chart was generated. I do not box features in green if they are only included in the NHC's longer term 5-day outlook.

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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 COLIN...
Current Prognosis...The broad circulation of Colin was about to make landfall in northwestern Florida as of 0000Z earlier this evening while centered just offshore at 29.3N-84.7W. Maximum sustained winds are estimated to be at 50 mph...with all tropical storm force winds measured to be in a broad area southeast of the center. Heavy showers and thunderstorms continue to be in a large area north and east of the center across Florida and parts of the southeastern United States.

Atmospheric Outlook for the Forecast Period...Tropical Storm Colin will continue to accelerate northeastward across the southeastern United States and into the western Atlantic while steered by southwesterly flow on the south side of the intensifying 985 mb frontal cyclone currently located over eastern North America. The west side of the tropical cyclone will continue to be covered by upper southwesterly flow that will continue to keep all of Colin's weather suppressed to the east half of the circulation. In the next 24 hours...despite landfall and southwesterly vertical shear...Colin will maintain strength while transitioning into a non-tropical remnant gale supported by the upper divergence on the east side of the upper trough associated with the aforementioned frontal cyclone.

Thermodynamic Outlook for the Forecast Period...In the next 24 hours...Colin will be quickly approaching the 26 deg C isotherm and cooler waters...which will aid in the transition to non-tropical.


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

24 Hr Forecast (0000Z Jun 8)...50 mph maximum sustained wind non-tropical remnant gale in the northwestern Atlantic centered at 37N-70W

Track Forecast...Colin has been tracking more northward than eastward...which requires a northward adjustment in the forecast track when compared to 24 hours ago. But finally during sunset...visible satellite imagery showed the center of Colin make a sharp right (northeastward) turn...with the northeastward track lining up with the latest NHC forecast which shows Colin making landfall across north Florida and then staying over or close to the southeast US coast thru Cape Hatteras North Carolina. Therefore I have no reason to disagree with the lastest NHC forecast track. My 0000Z Jun 8 (8 PM Tue) forecast position is based on the 1800Z GFS computer model run from earlier this evening.

Intensity Forecast...Maintenance of strength (despite landfall and southwesterly vertical shear) is expected as Colin transitions into a non-tropical remnant gale supported by the upper divergence on the east side of the upper trough associated with the eastern North America frontal cyclone.

Impact Forecast...Impact swath of 40+ mph tropical storm winds in the above graphic is extrapolation of the 11 PM EDT NHC tropical storm wind field along the forecast track. Since special update #28C..the large rain shield of Colin has retreated from northwestern Florida...southern Alabama...much of Georgia...and northwestern South Carolina. Therefore the heavy rainfall statement in the above forecast graphic does not include these areas.

2016 Atlantic Hurricane Season Birdseye Discussion #28C (Special Update)

By: NCHurricane2009, 5:38 PM GMT on June 06, 2016

...MONDAY JUNE 6 2016 1:40 PM EDT...
The following is a special update concerning Tropical Storm Colin in the eastern Gulf of Mexico

Tropical Storm Colin continues to not show signs of consolidating beneath its eastern center mentioned in special updates #28A and #28B. Instead Colin has evolved into an unusually broad...large sized tropical storm with a largely cloud-free circulation in the eastern Gulf of Mexico with thick clouds covering much of the southeastern United States and Florida. Due to the expansion of the storm...heavy rainfall is covering a much larger portion of the southeastern United States than previously anticipated. Therefore in my next full blog update tonight...will note that the heavy rainfall (with flash flood potential) will now affect the entire state of Florida...southern Alabama...the southern two-thirds of Georgia...most of South Carolina...and the eastern half of North Carolina. Continue to visit www.nhc.noaa.gov for up to the minute latest information on Tropical Storm Colin. See discussion #28 for information on the rest of the Atlantic tropics.

2016 Atlantic Hurricane Season Birdseye Discussion #28B (Special Update)

By: NCHurricane2009, 11:51 AM GMT on June 06, 2016

...MONDAY JUNE 6 2016 7:53 AM EDT...
The following is a special update concerning Tropical Storm Colin in the eastern Gulf of Mexico and remnants of Tropical Storm Bonnie in the open central Atlantic.

Overnight...aircraft reconaissance has determiend that Colin continues to have a complex structure with two tighter surface spins inside of a larger circulation. One is located in the deep and somewhat organized thunderstorm cluster currently in the eastern Gulf of Mexico around 85.5W longitude. The other is located well away from the thunderstorms at 89W longitude. As a compromise...the National Hurricane Center splits the difference and keeps Colin centered at 87.4W longitude. Aircraft reconaissance also measured sustained winds at the surface as high as 70 mph with the eastern center at 85.5W longitude...but for now the hurricane center has bumped up the estimated strength to 50 mph due to some uncertainty in those measurements. Therefore the possibility remains that the easern center becomes the dominant later today and Colin becomes stronger and tracks further to the right than previously forecast (as stated in special update #28A). If the eastern center were to dominate...the adjusted forecast would take the landfall point a bit further south towards Tampa Bay and have the storm exit northeast Florida to the south of 30N latitude...and maximum strength could be as high as 60 to 70 mph at landfall. Continue to visit www.nhc.noaa.gov for up to the minute latest information on Tropical Storm Colin. See discussion #28 for information on the rest of the Atlantic tropics.

The remnant of Tropical Storm Bonnie has continued tracking southeastward and is now in warmer waters in the open central Atlantic. As a result Bonnie has re-fired some deep thunderstorms near its center. However visible satellite imagery this morning also suggests that Bonnie has lost its closed circulation (i.e. there is no closed cloud swirl) as Bonnie begins to lose her surface low pressure field against the adjacent north-central Atlantic frontal depression that is expanding and strengthening. Without a closed circulation...Bonnie will not re-generate into a tropical cyclone.

2016 Atlantic Hurricane Season Birdseye Discussion #28A (Special Update)

By: NCHurricane2009, 11:00 PM GMT on June 05, 2016

...SUNDAY JUNE 5 2016 7:00 PM EDT...
Tropical depression three stregnthens to Tropical Storm Colin with 40 mph maximum sustained winds. Latest satellite imagery suggests the center of Colin is re-organizing further eastward toward 86W longitude...a location embedded in its mass of thunderstorms. Furthermore the thunderstorm activity is becoming more quickly organized around this possible new center. If current trends continue...a forecast adjustment may be needed (to increase forecast strengthening and to show a more eastward track which would show a landfall on the west-central Florida coast instead of the northwest Florida coast). Continue to visit www.nhc.noaa.gov for up to the minute latest information on Tropical Storm Colin. See discussion #28 for information on the rest of the Atlantic tropics.

On a final note...Colin is the earliest third troipcal storm on record since record keeping begain in 1851. This is a rather active start to the 2016 Atlantic Hurricane Season.

2016 Atlantic Hurricane Season Birdseye Discussion #28

By: NCHurricane2009, 6:29 PM GMT on June 05, 2016

...SUNDAY JUNE 5 2016 2:30 PM EDT...
Tropical disturbance Invest 93-L has intensified into the third tropical depression of the 2016 Atlantic Hurricane season this morning while establishing a closed circulation that has moved across the Yucatan peninsula of southeastern Mexico and into the southern Gulf of Mexico. Tropical storm conditions expected to overspread the eastern Gulf of Mexico and parts of Florida in the next 24 to 48 hours...tropical storm warning are in effect. Gale conditions are expected over a large portion of the western Atlantic by 72 hours and beyond after this system transition to non-tropical. See special feature section below for additional details on this system. Visit www.nhc.noaa.gov for up to the minute latest information on this tropical cyclone.

Bonnie has dissipated into a remnant low and is continuing southeastward in the northwesterly flow of a 1004 mb frontal depression in the north-central Atlantic. The cold front of the frontal depression is expected to eventually absorb Bonnie and therefore another episode of tropical cyclone reformation is not expected from Bonnie.

The 1010 mb surface low over southern Texas has drifted offshore and is currently at 1008 mb in the northwestern Gulf of Mexico. It has become significantly less active while battling for dominance between the 998 mb frontal cyclone over the eastern US to the north and newly-formed tropical depression three to the southeast. Given that tropical depression three has formed further to the northwest and closer to this surface low...the most likely outcome is that the surface low gets absorbed by the west side of tropical depression three. However will continue to watch for the development of a surface trough across the Gulf of Mexico in the wake of tropical depression three...esepcially as favorable upper ridging is expected to persist across the region. Currently the usually over-agressive CMC computer model is the only model that shows tropical development from such a surface trough.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1200Z and 1320Z-released WPC analysis.

Features boxed in green...if any...are mentioned in the National Hurricane Center (NHC) traditional 48-hour outlook and or are considered an "Invest" on the Naval Research Laboratory site of the US Navy at the time the chart was generated. I do not box features in green if they are only included in the NHC's longer term 5-day outlook.

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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 DEPRESSION THREE...
Current Prognosis...Over the past 24 hours...the western of the two Caribbean tropical waves has merged with the surface trough developing over southeastern Mexico...resulting in a broad but closed surface low pressure circulation centered just north of the Yucatan peninsula at 21.9N-88.1W. As a result...the National Hurricane Center has declared the third tropical depression of the 2016 Atlantic Hurricane Season. This system has formed further to the northwest than I previously forecasted...placing it closer to the upper southwesterly winds associated with the upper vortex near southern Texas and central US upper trough associated with the intensifying 998 mb frontal cyclone. The upper southwesterly winds are keeping all heavy weather associated with the tropical depression lopsided to the east side of the circulation. The heavy weather is currently overspreading the southeastern Gulf of Mexico...western Cuba...and northwestern Caribbean Sea.

Atmospheric Outlook for the Forecast Period...Tropical depression three will soon accelerate northeastward across the eastern Gulf of Mexico and Florida peninsula while getting pulled into the southwesterly flow on the south side of the intensifying 998 mb frontal cyclone currently moving into the eastern US. The west side of the tropical cyclone will be covered by upper southwesterly flow that will keep all of the cyclone's weather suppressed to the east half of the circulation...while the east half of the tropical cyclone will breath under the outflow of upper ridging (marked by blue-zig-zag line to the right of the tropical depression in the above atmospheric features chart)...resulting in heavy rain and gusty winds in the east half of this system...and perhaps a little further intensification to tropical storm strength. By the end of the forecast period (48 to 72 hours)...despite landfall with Florida and hostile westerly vertical shear...some additional strengthening is expected as the tropical cyclone transitions into a non-tropical remnant gale supported by the upper divergence on the east side of the upper trough associated with the eastern US frontal cyclone.

Thermodynamic Outlook for the Forecast Period...This system will be over rather favorable water temps of 28 to 30 deg C early in the forecast period. By the end of the forecast period (72 hours)...this system will be quickly approaching the 26 deg C isotherm and cooler waters...which will aid in the transition to non-tropical.


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

24 Hr Forecast (1200Z Jun 6)...45 mph maximum sustained wind tropical storm centered in the eastern Gulf of Mexico at 26N-87W.

48 Hr Forecast (1200Z Jun 7)...45 mph maximum sustained wind tropical storm centered over northeastern Florida at 30N-81.2W.

72 Hr Forecast (1200Z Jun 8)...50 mph maximum sustained wind non-tropical remnant gale along cold front in the western Atlantic centered northwest of Bermuda...at 37.5N-66W

Track Forecast...As noted in the above current prognosis...tropical depression three has formed further northwest than I previously thought...and I've noted that the initial position of the tropical depression is a bit further west than the 0600Z GFS computer model run. Therefore my updated forecast track is a northward adjustment over my previous and is similar but further west when compared to the 0600Z GFS model run.

Intensity Forecast...Only modest strengthening to a tropical storm expected as some unfavorable westerly vertical shear will be present across this system through the duration of the forecast period. Some additional strengthening or maintenance of strength (despite landfall with Florida) is expected as the tropical cyclone transitions into a non-tropical remnant gale supported by the upper divergence on the east side of the upper trough associated with the eastern US frontal cyclone.

Impact Forecast...Impact swath of 40+ mph tropical storm winds in the above graphic is based on a system with all heavy weather east of the center...which keeps the swath east of the northward track early in the forecast period...but is still symmetrical about the norhteastward track later in the forecast period. Some heavy rain for the norhteastern Yucatan peninsula of Mexico cannot be ruled out in the next 24 hours if some of the heavy weather just offshore briefly expands onshore. The tropical storm wind swath and statement of heavy rain may have to be expanded northward along the entire Carolina coast (up to Cape Hatteras) if the storm track is further north like the lastest NHC forecast shows.

2016 Atlantic Hurricane Season Birdseye Discussion #27

By: NCHurricane2009, 5:49 PM GMT on June 04, 2016

...SATURDAY JUNE 4 2016 1:50 PM EDT...
Bonnie regained tropical storm status in the western Atlantic over the last 36 hours...but has now weakened back to a tropical depression. Dissipation is expected shortly...see first special feature section below for additional details.

The tropical disturbance supported by the developing surface trough near southeastern Mexico and pair of tropical waves moving across the western Caribbean region has become better organized and as a result is now designated as Invest 93-L. Invest 93-L is expected to become a tropical storm in the next 48 hours. Preparations for tropical storm conditions should begin for the northeastern Yucatan peninsula...western Cuba...and across the Florida peninsula and Florida Keys. By 96 to 120 hours...this system will be rapidly moving northeast across much of the western Atlantic region while transitioning into a non-tropical remnant gale affecting marine interests. See second special feature section below for additional details on this developing situation.

A cut-off upper vortex over Texas has been contributing to numerous showers and thunderstorms over grounds that have been already soaked by severe thunderstorms over the last several days. This has resulted in some signficant flooding across the eastern half of the state. Currently the showers and thunderstorms supported by the divergence on the east side of the upper vortex have become concentrated along the southeast part of the state and the coast...over southern Lousiana...and parts of the northwestern Gulf of Mexico. A non-frontal surface 1010 mb low also supported by the upper vortex has developed over southern Texas and near the Gulf coast. It is possible that the surface low and aforementioned thunderstorm activity drifts eastward across the Gulf of Mexico in the wake of tropical disturbance Invest 93-L...and develops into a surface trough trailing behind 93-L after 93-L moves into the Atlantic from Florida. Some favorable upper ridging is expected to persists across the Gulf of Mexico in the wake of 93-L...and therefore will watch for potential for tropical development. Currently the only computer model that shows develpoment is the usually overly-aggressive CMC model.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0600Z and 0732Z-released WPC analysis.

Features boxed in green...if any...are mentioned in the National Hurricane Center (NHC) traditional 48-hour outlook and or are considered an "Invest" on the Naval Research Laboratory site of the US Navy at the time the chart was generated. I do not box features in green if they are only included in the NHC's longer term 5-day outlook.

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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 DEPRESSION BONNIE...
Current Prognosis...Within the last 36 hours...Bonnie regained tropical storm status as expected. Now Bonnie is back to tropical depression status after moving east-southeast out of the warm band of Gulf stream waters and into cooler waters...and as westerly vertical shear is finally taking its toll on Bonnie. Satellite imagery earlier this morning shows a cloud swirl with the remaining thunderstorms dissipating...and as of this very moment Bonnie is a thin cloud swirl with no thunderstorms. Satellite imagery shows Bonnie was at 35.8N-68.1W as of 0900Z and was at 35.6N-67.1W as of 1200Z

Atmospheric Outlook for the Forecast Period...Bonnie is embedded in upper westerly shearing winds as the shortwave upper trough over eastern Canada (currently supporting a 1012 mb frontal depression over eastern Canada and developing 1010 mb frontal depression immediately northeast of Bonnie) nears. However Bonnie is moving quickly east-southeastward in the flow on the southwest side of the 1010 mb frontal depression...and the fast forward motion is somewhat matching the upper westerly wind speed and thus minimizing (but not eliminating) the effects of westerly vertical shear. One could argue that Bonnie could continue southeastward back into warmer waters...and with the westerly shear being non-severe...maintain tropical cyclone status. However the 1010 mb frontal depression will drive a cold front southward into Bonnie...with the front absorbing whatever is left of Bonnie.

Thermodynamic Outlook for the Forecast Period...Bonnie has moved east-southeastward out of the warm band of warm Gulf stream waters above 26 deg C...and into cooler waters of 25 deg C not as supportive for tropical development. This maybe partly why Bonnie has weakened back to tropical depression status this morning.


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

12 Hr Forecast (0000Z Jun 5)...Remnant low centered at 34.8N-63.1W

Track Forecast...I expect that Bonnie will remain a cloud swirl void of thunderstorms and therefore predict Bonnie will be downgraded to a remnant low shortly. Therefore with the short-term steering trends remaining basically the same...my forecast track is based on extrapolating the 3-hourly motion noted in the above current prognosis section.

Intensity Forecast...I expect the moderate westerly shear and cooler waters of 25 deg C will cause Bonnie's dissipation in the next 12 hours.

Impact Forecast...As Bonnie dissipates...no significant impacts expected.

...SPECIAL FEATURE...WESTERN CARIBBEAN DISTURBANCE INVEST 93-L...
Current Prognosis...A tropical wave is over the western Caribbean sea at 85W longitude. A surface trough is currently near southeastern Mexico at a location just northwest of the Yucatan Peninsula while supported by upper divergence on the southeast side of the upper vortex that is over southern Texas. Another tropical wave is emerging from northwestern South America and into south-central Caribbean Sea at 75.5W. Organized thunderstorm squalls are currently present over Cayman Islands and W Caribean Sea...mainly concentrated with the western of the two aforementioned tropical waves. Over the last 36 hours...the increased organization of the thunderstorms has warranted an upgrade to designation Invest 93-L.

Atmospheric Outlook for the Forecast Period...As long expected...widespread favorable upper ridging has developed across the western Caribbean Sea (marked by blue-zig-zag line in the above atmospheric features chart). The outflow of the upper ridging will help keep surface pressures and vertical shear favorably low for tropical development as the pair of tropical waves mentioned in the above current prognosis move across the region. Therefore there is a very high chance of tropical cyclone formation in the next 48 hours as the surface trough and tropical waves mentioned in the above current prognosis merge. I continue to have my forecast (shown below) to be south and east of the latest computer model runs as I belieive the center of circulation will develop east of the Yucatan peninsula (instead of north of the Yucatan like many of the latest runs show)...closer to the core of the upper ridging. Whatever develops in this region will move northeastward across the eastern Gulf of Mexico and Florida peninsula while getting pulled into the southwesterly flow on the south side of the 1008 mb frontal cyclone currently over the north-central US (this frontal cyclone is expected to signifcantly intensify and expand while moving into the eastern US). The cut-off upper vortex over south Texas will begin merging with the upper-layers of the frontal cyclone...resulting in a SW-NE tilted upper trough that will cause the upper ridging over the forecast tropical storm to also become stretched into a SW-NE elongation...which in turn will cause westerly vertical shear over the tropical storm. The forecast locations of heavy weather shown below is based on a sheared tropical storm with the heaviest weather in the eastern half of the circulation (I've also shrunken the size of forecast heavy weather as this system is already more consolidated than I thought it would be by now). At the end of the forecast period...the cold front of the frontal cyclone will have overspread this system...resulting in transition into a non-tropical remnant gale while it speeds northeastward across the western Atlantic.

Thermodynamic Outlook for the Forecast Period...This system will be over rather favorable water temps of 28 to 30 deg C early in the forecast period. By the end of the forecast period...this system will be quickly approaching the 26 deg C isotherm and cooler waters...which will aid in the transition to non-tropical.

24 Hr Forecast (1200Z Jun 5)...Western tropical wave and southeastern Mexico surface trough merging into tropical low centered in the western Caribbean just east of the Yucatan Peninsula at 17.5N-86.5W...with the eastern tropical wave in the south-central Caribbean Sea becoming absorbed by the tropical low. Heavy weather becoming better organized and covering western Caribbean Sea...eastern Yucatan Peninsula...and western tip of Cuba.

48 Hr Forecast (1200Z Jun 6)...45 mph maximum sustained wind tropical storm centered just northwest of Cuba in the southeastern Gulf of Mexico at 23N-85.5W. Heaviest weather over southeastern Gulf of Mexico...Florida Keys...western Cuba...and northwestern Caribbean Sea.

72 Hr Forecast (1200Z Jun 7)...50 mph maximum sustained wind tropical storm centered over central Florida at 28N-81.2W. Heaviest weather east of the center and over the Florida peninsula...southeast Georgia...and northwestern Bahamas.

96 Hr Forecast (1200Z Jun 8)...50 mph maximum sustained wind non-tropical remnant gale along cold front in the western Atlantic midway between North Carolina and Bermuda...centered at 35N-70W

2016 Atlantic Hurricane Season Birdseye Discussion #26

By: NCHurricane2009, 5:27 AM GMT on June 03, 2016

...FRIDAY JUNE 3 2016 1:30 AM EDT...
Bonnie re-generates into a tropical depression while beginning to accelerate east-northeastward away from the North Carolina coast. Further intensification to a tropical storm is possible as Bonnie moves across the northwestern Atlantic...see second special feature section below for additional details.

The tropical wave that was east of the Lesser Antilles is now over northern South America. This tropical wave is expected to merge with the tropical wave and heavy weather currently in the central Caribbean Sea and surface trough expected to develop over southeastern Mexico...and develop into a large-sized tropical storm in about 96 hours. See second special feature section below for additional details on this developing situation. Interests in the western Caribbean Sea and eastern Gulf of Mexico should monitor this situation carefully. In the long range...this system is likely to move across the Florida peninsula and western Bahamas...and into the western Atlantic. A very long-range effect to Bermuda cannot be ruled out.

...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.

Features boxed in green...if any...are mentioned in the National Hurricane Center (NHC) traditional 48-hour outlook and or are considered an "Invest" on the Naval Research Laboratory site of the US Navy at the time the chart was generated. I do not box features in green if they are only included in the NHC's longer term 5-day outlook.

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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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 DEPRESSION BONNIE...
Current Prognosis...Bonnie looks like a classic compact tropical cyclone on satellite imagery this evening...with symmertical spiral outer bands and a central dense overcast...albeit the central dense overcast is slightly biased ot the north of the surface center. As of the 11 PM EDT National Hurricane Center advisory...the center of tropical depression Bonnie was located just east of Cape Hatteras North Carolina at 35.7N-74.3W and is beginning to accelerate east-northeastward away from the Carolina coast and into the northwestern Atlantic.

Atmospheric Outlook for the Forecast Period...Bonnie is beginning to accelerate east-northeastward into the northwestern Atlantic in the southwesterly flow ahead of the 1005 mb frontal cyclone currently approaching Bonnie from the northeastern US/eastern Canada. By 48 hours...the shortwave upper trough associated with the frontal cyclone will support the formation of a surface frontal depression in the northwestern Atlantic...along the front that is already in the northwestern Atlantic to the northeast of Bonnie. The latest computer model runs suggest that Bonnie will become absorbed by the southwest side of the developing frontal depression at 48 hours. On an interesting note...westerly vertical shear over Bonnie was supposed to be increasing by now as the shortwave upper trough from the SE US to central Caribbean is currently de-amplifying...and as the strong upper westerlies associated with the 1005 mb frontal cyclone's shortwave upper trough are nearing. However it appears the latent heat release of Bonnie's thunderstorm core has produced a tall enough vertical warm core such that a weak upper anticyclone is trying to develop over the storm...with the the partial upper anticyclone helping to deflect some of the westerly vertical shear. Coupled with the fact that Bonnie going to accelerate faster to the east-northeast and increasingly match the upper westerly wind speed...westerly vertical shear probably won't be as strong as previously thought.

Thermodynamic Outlook for the Forecast Period...Early part of the forecast track keeps Bonnie on the north edge of the warm Gulf stream waters in the northwestern Atlantic. As noted in the track forecast section below...I have adjusted the later part of the track forecast further south such that Bonnie is now expected to move into the favorable core of the warm Gulf stream which is currently above 26 deg C.


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

24 Hr Forecast (0000Z Jun 4)...45 mph maximum sustained wind tropical storm centered in the northwestern Atlantic at 36.5N-71W

48 Hr Forecast (0000Z Jun 5)...Remnant low centered at 37.5N-65W...becoming absorbed by frontal depression in the northwestern Atlantic

Track Forecast...Bonnie is currently north of my previous forecast track...and yet the NHC forecast is south of my previous forecast track. Bonnie is beginning to show signs of deflecting more eastward and re-aligning with my prior forecast track...and therefore I prefer to not change my more north forecast track for the first 24 hours. The latest computer model runs suggest Bonnie will be moving into the southwest quadrant of a developing frontal depression in the NW Atlantic (see above atmospheric outlook section). The northerly flow on the west side of the frontal depression will help keep Bonnie on a more south track...and therefore I have adjusted my 48 hr forecast position further to the south...but I still lie north of the NHC forecast track.

Intensity Forecast...Westerly vertical shear is not as strong as previously expected (see above atmospheric outlook section). My southward adjusted forecast track will place Bonnie into the core of the warm Gulf stream waters (see above theromdynamic outlook section). The National Hurricane Center 5 PM EDT advisory discussion suggested that Bonnie's estimated strength may be conservative at the moment. Therefore I have adjusted my intensity forecast slightly upward. It wouldn't surprise however if Bonnie exceeds current intensity forecasts in the next 24 hours.

Impact Forecast...Expect the development of some sea swells and tropical storm force winds in the northwestern Atlantic near the storm track.

...SPECIAL FEATURE...DEVELOPING CARIBBEAN SEA DISTURBANCE...
Current Prognosis...According to the National Hurricane Center Tropical Analysis Forecast Branch (TAFB) surface analysis from earlier this evening...a tropical wave is in the south-central Caribbean Sea at 77W longitude...and another tropical wave is over northern South America at 64W longitude. The cut-off upper trough that was over the southeastern US to central Caribbean Sea is in the process of dissipating with a western upper ridge axis expanding in from Central America and an eastern upper ridge axis expanding from the eastern Caribbean. Strong upper divergence between northerlies across the western upper ridge axis and westerlies at the base of the dissipating upper trough have produced significant thunderstorm activity over the Central Caribbean Sea...and it is probable the western of the two aforementioned tropical waves is contributing to this activity.

Atmospheric Outlook for the Forecast Period...As the cut-off upper trough over the southeastern US to central Caribbean Sea continues to weaken...widespread favorable upper ridging will develop in its wake across the Caribbean. The outflow of the upper ridging will help keep surface pressures and vertical shear favorably low for tropical development as the pair of tropical waves mentioned in the above current prognosis move across the Caribbean. In addition...the cut-off upper vortex over Texas will be reaching the Gulf of Mexico and support the formation of a surface trough over southeastern Mexico. Current expectation is that the surface trough and pair of tropical waves merge into a large-sized tropical cyclone by 96 hours as detailed in the forecast shown below. I have shifted my forecast point of tropical cyclone formation eastward when compared to my previous forecast as I believe this will be the location of maximal upper divergence near the core of the forecast upper ridging. Whatever develops in this region will move northeastward across the eastern Gulf of Mexico and Florida peninsula while getting pulled into the south side of what is forecast to be a massive deep-layered frontal cyclone over the eastern US. The cut-off upper vortex over Texas will begin merging with the upper-layers of the frontal cyclone...resulting in a SW-NE tilted upper trough that will cause the upper ridging over the forecast tropical storm to also become stretched into a SW-NE elongation...which in turn will cause westerly vertical shear over the tropical storm. The forecast locations of heavy weather shown below is based on a sheared tropical storm with the heaviest weather in the eastern half of the circulation.

Thermodynamic Outlook for the Forecast Period...This system will be over rather favorable water temps of 28 to 30 deg C thru the forecast period.

24 Hr Forecast (0000Z Jun 4)...Surface trough developing over southeastern Mexico due to upper divergence southeast of Texas upper vortex. Tropical wave moving into Central America at 84W longitude. Tropical wave over northwestern South America at 72.5W longitude. Heaviest weather moving into western Caribbean and Central America...with additional thunderstorms over southeastern Mexico and northwestern South America.

48 Hr Forecast (0000Z Jun 5)...Surface trough over southeastern Mexico. Tropical wave over the western Caribbean/Central America at 87.5W longitude. Tropical wave over the south-central Caribbean Sea at 77.5W longitude. Heaviest weather concentrating with the western tropical wave and surface trough and expanding in size beneath core of expanding upper ridge over the western Caribbean Sea...western Central America...and southeastern Mexico. Additional thunderstorms over south-central Caribbean Sea.

72 Hr Forecast (0000Z Jun 6)...Large broad tropical low pressure centered in the western Caribbean Sea just east of the Yucatan Peninsula at 17.5N-86.5W...with the eastern tropical wave in the south-central Caribbean Sea becoming absorbed by the tropical low. Heavy weather becoming better organized and covering western Caribbean Sea...eastern Yucatan Peninsula...Cayman Islands...western Cuba...with outer squalls reaching western Central America and south-central Caribbean Sea.

96 Hr Forecast (0000Z Jun 7)...Large broad tropical storm with 45 mph maximum sustained winds centered in the southeastern Gulf of Mexico just north of western Cuba at 23.5N-84.8W. Heaviest weather over southeastern Gulf of Mexico...south Florida...western Cuba...and northwestern Caribbean Sea.

120 Hr Forecast (0000Z Jun 8)...Large broad tropical storm with 50 mph maximum sustained winds centered over south Florida at 26.5N-81.2W. Heaviest weather over Florida Peninsula...western Bahamas...and central Cuba.

2016 Atlantic Hurricane Season Birdseye Discussion #25

By: NCHurricane2009, 3:09 AM GMT on June 02, 2016

...WEDNESDAY JUNE 1 2016 11:10 PM EDT...
Heavy weather to affect the Outer Banks of North Carolina near Cape Hatteras over the next 24 hours as Bonnie shows signs of re-generating into a tropical depression or tropical storm. Marine interests in the northwestern Atlantic should monitor the remnants of Bonnie for re-genesis as they are forecast to accelerate northeastward from the coast of North Carolina after 24 hours. See first special feature section below for additional details.

The surface trough northeast of the Bahamas that was supported by divergence on the east side of the cut-off upper trough from the southeastern United States to central Caribbean has dissipated...and the associated showers and thunderstorms have become less organized as vertical shear has increased as the cut-off upper trough begins to de-amplify. Tropical cyclone formation here is not expected.

As the cut-off upper trough over the southeastern US to central Caribbean Sea weakens...computer models show an upper ridge developing over the western Caribbean Sea in its wake. The outflow of the upper ridge could keep surface pressures low and also keep vertical shear favorably low...and the tropical wave currently east of the Lesser Antilles (currently en route to the Caribbean Sea) could develop into a tropical cyclone while moving across the western Caribbean Sea in 96 to 120 hours (4 to 5 days). This system has already gained attention in the National Hurricane Center 5-day tropical weather outlook...and computer model support continues to increase. Interests in the western Caribbean Sea and eastern Gulf of Mexico should monitor this situation over the next few days. See second special feature section for additional details.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1935Z-released WPC analysis.

Features boxed in green...if any...are mentioned in the National Hurricane Center (NHC) traditional 48-hour outlook and or are considered an "Invest" on the Naval Research Laboratory site of the US Navy at the time the chart was generated. I do not box features in green if they are only included in the NHC's longer term 5-day outlook.

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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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...REMNANT OF BONNIE (INVEST 92-L)...
Current Prognosis...The remnant low of Tropical Storm Bonnie has drifted eastward to a position offshore of North Carolina. Both radar and satellite imagery show that Bonnie is re-organizing into a rather compact tropical circulation that features a circular storm burst just northeast of the center...with the center currently located just south-southwest of Cape Hatteras North Carolina at 34N-76W as of 0000Z this evening.

Atmospheric Outlook for the Forecast Period...The remnant low of Bonnie has been moving slowly northeastward while trapped between the 1017 mb ridge over the southeastern US and 1026 mb ridge in the Atlantic. After 24 hours...Bonnie will be accelerating northeastward while the 1002 mb frontal cyclone currently over the north-central US pulls Bonnie out from between the ridges. The warm front of the frontal cyclone extends hundreds of miles eastward and is already in the northwestern Atlantic..and by 72 hours Bonnie should lose tropical character while merging with the warm front...or alternatively Bonnie will be absorbed by a frontal depression that develops on the warm front (with the frontal depression being supported by divergence on the east side of the shortwave upper trough associated with the frontal cyclone). Even though westerly vertical shear is expected to increase at 24 hours and beyond (due to the de-amplification of the cut-off upper trough over the SE US-to-central Caribbean...and due to the approach of the shortwave upper trough of the frontal cyclone)...I still forecast Bonnie to regain minimal tropical storm status by 24 to 48 hours as this is also the time Bonnie will be accelerating northeastward...which will help her match the upper westerly wind speed and reduce the westerly shear somewhat. But because I still expect westerly shear to still be a factor...I do not show Bonnie re-developing into a strong tropical storm.

Thermodynamic Outlook for the Forecast Period...Forecast track keeps Bonnie on the north edge of the warm Gulf stream waters in the northwestern Atlantic which are currently 26 deg C or above and therefore water temps along the forecast track are supportive for Bonnie to regain tropical cyclone status.

24 Hr Forecast (0000Z Jun 3)...40 mph maximum sustained wind tropical storm centered just east of Cape Hatteras North Carolina...at 35N-74W

48 Hr Forecast (0000Z Jun 4)...40 mph maximum sustained wind tropical storm centered in the northwestern Atlantic at 36.5N-71W

72 Hr Forecast (0000Z Jun 5)...Remnant low along warm front in the northwestern Atlantic...located at 37.5N-65W

...SPECIAL FEATURE...TROPICAL WAVE APPROACHING THE CARIBBEAN SEA...
Current Prognosis...As of 1800Z earlier this evening...the National Hurricane Center Tropical Analysis Forecast Branch (TAFB) placed a tropical wave at 56 degrees west longitude in the tropical belt of the Atlantic. The tropical wave is currently inactive while currently suppressed by upper convergence on the east side of an upper ridge in the eastern Caribbean Sea (marked by blue-zig-zag line in the above atmospheric features chart).

Atmospheric Outlook for the Forecast Period...Previous surface analyses from the TAFB suggest that the tropical waves in the Atlantic tropical belt have been moving rather quickly westward...at about 10 degrees longitude per day. This phases the tropical wave in the above current prognosis quiet well with tropical cyclogenesis in the western Caribbean Sea shown in computer models to be occurring in about 5 days (120 hours) from now. As the cut-off upper trough over the southeastern US to central Caribbean Sea weakens...widespread favorable upper ridging will develop in its wake across the Caribbean. The outflow of the upper ridging will help keep surface pressures and vertical shear favorably low as the tropical wave moves in the western Caribbean. In addition...the cut-off upper vortex over New Mexico and western Texas will be reaching the Gulf of Mexico...and it is possible that divergence on the east side of the upper vortex could further expand the field of low surface pressures (in addition the tropical wave further west...currently over northwestern Venezuela...could interact with this upper divergence and further re-enforce the size of the low pressure field). Therefore my current forecast below shows a large-sized tropical cyclone developing in the western Caribbean/Yucatan region in about 96 to 120 hours. At the end of the forecast period...whatever develops in this region is likely to move northward toward the eastern Gulf of Mexico into a ridge weakness caused by a large...impressive frontal cyclone forecast to be over the eastern US.

Thermodynamic Outlook for the Forecast Period...This system will be over rather favorable water temps of 29 to 30 deg C thru the forecast period.

24 Hr Forecast (0000Z Jun 3)...Tropical wave in the eastern Caribbean Sea at 66W longitude

48 Hr Forecast (0000Z Jun 4)...Tropical wave in the central Caribbean Sea to the southeast of Jamaica at 76W longitude

72 Hr Forecast (0000Z Jun 5)...Tropical wave in the western Caribbean Sea and over Central America at 85W longitude

96 Hr Forecast (0000Z Jun 6)...Large broad tropical low centered over the east coast of the Yucatan Peninsula at 17.5N-87.5W

120 Hr Forecast (0000Z Jun 7)...Large broad tropical storm with 45 mph maximum sustained winds centered over the northeastern Yucatan peninsula at 21N-87.5W

2016 Atlantic Hurricane Season Birdseye Discussion #24

By: NCHurricane2009, 5:33 AM GMT on June 01, 2016

...WEDNESDAY JUNE 1 2016 1:40 AM EDT...
The official start of the 2016 Atlantic Hurricane season is here...therefore continuing daily birdseye discussions on this blog till the season end in November 30. I may have pauses in my daily updates if long periods of inactivity develop or personal matters prevent me from doing daily updates.

The remnant low of Bonnie remains generally stationary over the eastern Carolinas and the waters just offshore while trapped between the 1016 mb ridge over the southeastern US and 1026 mb ridge over the Atlantic. Over the last day showers and thunderstorms have pulsed up and down just east of the center and over water. Latest radar imagery shows that the center has slid offshore and has become better organized with spiral rain bands. Therefore there is a window for Bonnie to re-generate into a tropical cyclone. However this window appears to be small as the cut-off upper trough from the southeastern US to central Caribbean Sea begins to shift eastward over Bonnie while de-amplifying in the next 24 hours...which will result in increasingly unfavorable westerly vertical shear over Bonnie fairly soon. After 48 hours...the 1002 mb surface frontal cyclone currently over the central US will reach Bonnie and pull the remnants out to sea. As Bonnie accelerates northeastward near the warm Gulf stream...there could be another small window for tropical cyclone reformation as Bonnie's track will allow it to catch up to the upper westerly winds which will reduce the effect of the vertical shear. However reformation during this time will also be difficult as the cold front of the frontal cyclone will have a high chance of absorbing Bonnie.

A surface trough northeast of the Bahamas continues to be supported by divergence between the east side of the cut-off upper trough from the southeastern United States to central Caribbean (marked by blue-dashed in the atmospheric features chart below) and west side of an upper ridge extending into the eastern Caribbean (marked by blue-zig-zag line). Showers and thunderstorms have not become any better organized...and the greatest concentration of this activity is displaced eastward from the surface trough which may be early signs of vertical shear. Conditions for additional tropical development will only be favorable for another 24 hours after which time the cut-off upper trough de-amplifies which will result in increased unfavorable westerly vertical shear over this activity. If tropical cyclone development were to occur...it would most likely track northeastward (potentially toward Bermuda) across the western Atlantic while the aforementioned cut-off upper trough shifts eastward...and while rounding the west side of the Atlantic surface ridge. Any tropical cyclone that develops from this system should also remain weak due to the aforementioned expected westerly vertical shear.

As the cut-off upper trough over the southeastern US to central Caribbean Sea weakens...computer models show a favorable upper ridge developing over the western Caribbean Sea in its wake. The outflow of the upper ridge could keep surface pressures low...and a tropical wave reaching this region could become better organized and develop in about a week from now as some of the latest computer model runs suggest.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1930Z-released WPC analysis.

Features boxed in green...if any...are mentioned in the National Hurricane Center (NHC) traditional 48-hour outlook and or are considered an "Invest" on the Naval Research Laboratory site of the US Navy at the time the chart was generated. I do not box features in green if they are only included in the NHC's longer term 5-day outlook.

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, blue Hs are locations of upper ridges.

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, Hs indicate surface highs.

...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).


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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