NCHurricane2009's Blog

2015 Atlantic Hurricane Season Birdseye Discussion #142A (Special Update)

By: NCHurricane2009, 4:28 AM GMT on November 30, 2015

...SUNDAY NOVEMBER 29 2015 11:30 PM EDT...
The large upper vortex in the western Atlantic remains centered over eastern Cuba. Divergence on the east side of the upper vortex is supporting a long surface trough with showers and thunderstorms over some of the northeastern Caribbean Islands and western Atlantic. There continue to be no signs of a subtropical or tropical system consolidating in this large weather system. And with the official end of the Atlantic Hurricane Season coming in the next 24 hours...I am ceasing daily updates on this blog until the threat of tropical activity returns to the Atlantic basin.

2015 Atlantic Hurricane Season Birdseye Discussion #142

By: NCHurricane2009, 3:08 AM GMT on November 29, 2015

...SATURDAY NOVEMBER 28 2015 10:15 PM EDT...
The large upper vortex in the western Atlantic is currently centered over eastern Cuba as marked by the blue L in the atmospheric features chart below. Divergence on the east side of the upper vortex is supporting a long surface trough with showers and thunderstorms over the eastern Caribbean...parts of the northeastern Caribbean Islands...and western Atlantic. There are no signs of a subtropical or tropical system consolidating in this large weather system.

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 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).

2015 Atlantic Hurricane Season Birdseye Discussion #141

By: NCHurricane2009, 5:40 AM GMT on November 27, 2015

...FRIDAY NOVEMBER 27 2015 12:40 AM EDT...
As long anticipated...the southern part of an upper trough that has recently emerged from eastern North America has evolved into a cut-off upper vortex in the western Atlantic to the southwest of Bermuda. There are no current signs of a subtropical surface low supported by the divergence on the east side of the upper vortex...but will continue to watch this upper vortex over the next few days.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0121Z-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).

2015 Atlantic Hurricane Season Birdseye Discussion #140

By: NCHurricane2009, 10:09 PM GMT on November 25, 2015

...WEDNESDAY NOVEMBER 25 2015 5:10 PM EDT...
The southern part of the upper trough that is currently emerging from eastern North America has become cut-off from the mid-latitude westerlies and will evolve into a cut-off upper vortex. Therefore watching for potential development of a subtropical surface low to the south of Bermuda to be supported by the divergence on the east side of the cut-off upper vortex over the next five days.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1200Z and 1338Z-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).

2015 Atlantic Hurricane Season Birdseye Discussion #139

By: NCHurricane2009, 2:16 AM GMT on November 24, 2015

...MONDAY NOVEMBER 23 2015 9:20 PM EDT...
The upper trough currently over the eastern North America is expected to leave behind a cut-off upper vortex as it moves into the western Atlantic over the next few days. Divergence on the east side of the upper vortex will trigger dropping surface pressures south of Bermuda. Therefore will watch for potential subtropical development next week.

...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).

2015 Atlantic Hurricane Season Birdseye Discussion #138

By: NCHurricane2009, 5:00 PM GMT on November 22, 2015

...SUNDAY NOVEMBER 22 2015 12:01 PM EDT...
The upper trough currently over the eastern North America is expected to leave behind a cut-off upper vortex as it moves into the western Atlantic over the next few days. Divergence on the east side of the upper vortex will trigger dropping surface pressures south of Bermuda. If the track of the surface low stays south enough for a sufficient period...it could acquire some tropical characteristics.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1200Z and 1336Z-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).

2015 Atlantic Hurricane Season Birdseye Discussion #137

By: NCHurricane2009, 2:10 AM GMT on November 21, 2015

...FRIDAY NOVEMBER 20 2015 9:10 PM EDT...
The tropical wave previously crossing the central Caribbean Sea has diminished and no activity is expected in the Caribbean.

Elsewhere...the upper trough currently over the north-central US is expected to amplify and then leave behind a cut-off upper vortex as it moves into the western Atlantic over the next five days. Divergence on the east side of the upper vortex will trigger a surface low south of Bermuda. If the track of the surface low stays south enough for a sufficient period...it could acquire some tropical characteristics.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1937Z-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).

2015 Atlantic Hurricane Season Birdseye Discussion #136

By: NCHurricane2009, 1:50 AM GMT on November 20, 2015

...THURSDAY NOVEMBER 19 2015 8:50 PM EDT...
The tropical wave currently crossing the central Caribbean Sea is about to reach favorable upper ridging in the western Caribbean being left behind by the upper ridge currently emerging from eastern North America. However the latest computer model runs suggest that this tropical wave will cross Central America and develop over the eastern Pacific instead.

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 1926Z-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).

2015 Atlantic Hurricane Season Birdseye Discussion #135

By: NCHurricane2009, 12:48 AM GMT on November 19, 2015

...WEDNESDAY NOVEMBER 18 2015 7:48 PM EDT...
Over the next few days the upper ridge currently emerging from eastern North America will expand into the western Caribbean and provide favorable upper winds for tropical development. During this time the tropical wave currently crossing the eastern Caribbean will reach these favorable upper winds. Therefore will continue to monitor the Caribbean for potential tropical development over the next few days. However the latest computer model runs suggest that this tropical wave will cross Central America and develop over the eastern Pacific instead.

...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.

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).

2015 Atlantic Hurricane Season Birdseye Discussion #134

By: NCHurricane2009, 11:10 AM GMT on November 18, 2015

...WEDNESDAY NOVEMBER 18 2015 6:11 AM EDT...
Over the next few days the upper ridge over eastern North America is expected to expand into the western Caribbean and provide favorable upper winds for tropical development. During this time the tropical wave currently crossing the Lesser Antilles will reach these favorable upper winds. Therefore will continue to monitor the Caribbean for potential tropical development over the next few days. However the latest computer model runs suggest that this tropical wave will cross Central America and develop over the eastern Pacific instead.

The upper trough currenlty crossing the central Atalntic is expected to produce a surface frontal gale in th eopen central Atlantic over the next 48 hours. The latest computer model runs suggest that it will quickly retreat north before having the chance to gain tropical characeteristics and therefore will no longer be menioned on these blog updates.

...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).

2015 Atlantic Hurricane Season Birdseye Discussion #133

By: NCHurricane2009, 6:17 PM GMT on November 16, 2015

...MONDAY NOVEMBER 16 2015 1:17 PM EDT...
Over the next five days the upper ridge over eastern North America is expected to expand into the western Caribbean and provide favorable upper winds for tropical development. During this time the tropical wave currently approaching the Lesser Antilles will be moving across the Caribbean...with potential for tropical cyclone formation from this tropical wave when it reaches the Caribbean. Therefore will continue to monitor the Caribbean for potential tropical development over the next few days.

The deep-layered and 978 mb surface frontal cyclone that has recently emerged into the western Atlantic has the potential to leave behind two cut-off weather systems to the east of the upper ridge over eastern North America. The first is the shortwave upper trough that has already been left behind over the eastern Gulf of Mexico and western Caribbean which is kicking off a large area of dropping surface pressures as well as showers and thunderstorms over the Bahamas...Cuba...and the central Caribbean (this area has been recently introduced into the National Hurricane Center tropical weather outlook and will contribute to the possible tropical cyclone formation mentioned in the previous paragraph if anything). The second is the potential for a large cut-off upper vortex to develop over the open central Atlantic which will support the formation of a surface frontal gale. Depending on the exact track of the surface gale...it could tap into warm enough waters and transition into a subtropical cyclone.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1200Z and 1326Z-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).

2015 Atlantic Hurricane Season Birdseye Discussion #132

By: NCHurricane2009, 4:21 PM GMT on November 15, 2015

...SUNDAY NOVEMBER 15 2015 11:21 AM EDT...
Over the next six days an upper ridge is expected to develop over eastern North America...with this upper ridge extending into the western Caribbean and providing favorable upper winds for tropical development. During this time the tropical wave currently in the central tropical Atlantic will be moving across the Caribbean...and some computer models (CMC and NAVGEM) indicate potential tropical cyclone formation from this tropical wave when it reaches the Caribbean. Therefore will continue to monitor the Caribbean for potential tropical development over the next few days.

The upper trough and 987 mb surface frontal cyclone that has recently emerged from eastern North America has the potential to leave behind two cut-off weather systems to the east of an upper ridge to develop over eastern North America. The first is the shortwave upper trough that has already been left behind over the eastern Gulf of Mexico and western Caribbean which has potential to evolve into a cut-off upper vortex over the central or eastern Caribbean Sea. However computer models have backed off on the expansiveness of this cut-off upper vortex and therefore it is less likely a tropical or subtropical disturbance will develop from this feature. The second is the potential for a large cut-off upper vortex to develop over the open central Atlantic which will support the formation of a surface frontal gale. Depending on the exact track of the surface gale...it could tap into warm enough waters and transition into a subtropical cyclone.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1200Z and 1329Z-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).

2015 Atlantic Hurricane Season Birdseye Discussion #131

By: NCHurricane2009, 6:21 PM GMT on November 14, 2015

...SATURDAY NOVEMBER 14 2015 1:21 PM EDT...
The upper ridge and associated disturbed weather over the western Caribbean has shifted into Central America while less favorable upper northwesterly flow has developed over water in the wake of the upper ridge. However over the course of the next week an upper ridge is expected to develop over eastern North America...with the upper ridge over Central America potentially expanding back into the southern Caribbean while merging with the upper ridge over eastern North America. Therefore will continue to monitor the southern Caribbean for potential tropical development over the next few days.

The upper trough and 991 mb surface frontal cyclone emerging over the eastern United States will be crossing the Atlantic over the next few days while leaving behind two cut-off weather systems to the east of an upper ridge to develop over eastern North America. The first is the potential for a cut-off upper vortex to develop over the central or eastern Caribbean Sea. However computer models have backed off on the expansiveness of this cut-off upper vortex and therefore it is less likely a tropical or subtropical disturbance will develop from this feature. The second is the potential for a large cut-off upper vortex to develop over the open central Atlantic which will support the formation of a surface frontal gale. Depending on the exact track of the surface gale...it could tap into warm enough waters and transition into a subtropical cyclone.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0600Z and 0713Z-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).

2015 Atlantic Hurricane Season Birdseye Discussion #130

By: NCHurricane2009, 5:49 AM GMT on November 13, 2015

...FRIDAY NOVEMBER 13 2015 12:50 AM EDT...
As expected Kate has transitioned into a remnant non-tropical gale while continuing northeast across the north Atlantic high seas.

Elsewhere...the upper ridge in the western Caribbean Sea continues to expand and its outflow continues to support an enhanced area of showers and thunderstorms moving toward the western Caribbean and Central America. Surface tropical waves passing through the Caribbean are also aiding this disturbed weather. Therefore the formation of a broad surface tropical low pressure will be possible in the southern Caribbean over the next couple of days. Computer models currently do not show tropical cyclone formation...perhaps because upper-level wind forecasts indicate the favorable upper ridge will shift westward over land (Central America) while less favorable upper northwesterly flow gradually takes its place over water by 48 to 72 hours.

In about a week from now...the strong upper trough and 989 mb surface frontal cyclone over the United States will be crossing the Atlantic while having the potential to leave behind a cut-off upper vortex in the central Caribbean Sea. Divergence on the northeast side of the cut-off upper vortex may trigger a surface subtropical or tropical disturbance in the western Atlantic to the northeast of the Dominican Republic.

...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.

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).

2015 Atlantic Hurricane Season Birdseye Discussion #129

By: NCHurricane2009, 4:53 AM GMT on November 12, 2015

...WEDNESDAY NOVEMBER 11 2015 11:53 PM EDT...
Special statement: A strong frontal cyclone over the central US will be bringing high winds to my location in southeastern Michigan in the next 24 hours. Therefore I may not be able to post a blog update tomorrow if a power outage occurs at my residence.

Kate weakens back to a tropical storm this evening while continuing to race across the north Atlantic. Kate is expected to soon transition into a large and powerful non-tropical remnant gale that will threaten shipping interests in the Atlantic high seas. See special feature section below for additional details on Kate.

While continuing to weaken...upper vorticity in the Caribbean Sea has split into an upper trough in the western Caribbean Sea and another upper trough in the eastern Caribbean. An upper ridge has developed between the two upper troughs...with outflow from the upper ridge and upper divergence on the east side of the western Caribbean upper trough continuing to support showers and thunderstorms across the southern Caribbean Sea. Surface tropical waves passing through the Caribbean may also be aiding this disturbed weather. Therefore the formation of a broad surface tropical low pressure will be possible in the southern Caribbean over the next couple of days. Computer models currently do not show tropical cyclone formation...perhaps beacause upper-level wind forecasts indicate the favorable upper ridge will shift westward over land (Central America) while less favorable upper northwesterly flow gradually takes its place over water by 72 hours.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0140Z-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 KATE...
Current Prognosis...As of 0000Z Kate was centered at 39.2N-54.3W...and has reached 40.1N-52.3W as of 0300Z while continuing to race northeastward under the influence of an upper trough and surface 994 mb frontal cyclone that has recently emerged into the western Atlantic. Despite the presence of very strong upper westerly winds across the tropical cyclone...Kate has been able to avoid getting sheared due to her fast northeast track that has allowed the surface center to keep up with the upper westerly wind speed. Coupled with supportive upper divergence on the east side of the aforementioned upper trough...Kate continues to remain a strong tropical cyclone. However she has slightly weakened to 70 mph winds while moving into increasingly cooler waters.

Atmospheric Outlook for the Forecast Period...Kate will be controlled by the 994 mb surface frontal cyclone and upper trough currenly in the western Atlantic. The frontal cyclone will continue to accelerate Kate northeastward while the upper trough will help transition Kate into a very strong non-tropical remnant gale supported by the upper divergence on the east side of the upper trough. With Kate currently at high-end tropical storm strength...she is now the dominant center of this mid-latitude system and therefore will soon absorb the frontal cyclone instead of the other way around. Therefore Kate will spend the next couple of days threatening the entire north Atlantic high seas as a strong remnant gale.

Thermodynamic Outlook for the Forecast Period...Kate crossed the 26 deg C isotherm into cooler waters several hours ago which is aiding in the current transition from tropical to non-tropical status.


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

24 Hr Forecast (0000Z Nov 13)...70 mph maximum sustained wind non-tropical remnant gale centered at 43N-46.5W

Track Forecast...By extrapolating the very rapid 2W longitude per 3 hour (16W longitude per 24 hour motion) noted in the above current prognosis...one might expect Kate to have already crossed 40W longitude by 24 hours. However all computer models show Kate slowing down in the next 24 hours while performing a slight fujiwhara-like interaction with the adjacent frontal cyclone to her west (it is also during this interaction that Kate is expected to absorb the frontal cyclone and become the dominant gale center in the area). Kate has had a history of being slightly northeast of previous track forecasts (for instance the 0300Z position indicates Kate has arrived to its current location 3 hours earlier than my previous forecast showed). Plus Kate at 0300Z is slightly north of where the 1800Z GFS computer model puts Kate at 0300Z. Therefore my 24 hour forecast point is slightly northeast of the GFS model for that time.

Intensity Forecast...I show Kate maintaining current strength for the next 24 hours while it continues to be supported by strong upper divergence on the east side of an upper trough as noted in the above atmospheric outlook section.

Impact Forecast...Impact swath is an extrapolation of the 10 PM EDT tropical storm wind field along my forecast track.

2015 Atlantic Hurricane Season Birdseye Discussion #128

By: NCHurricane2009, 12:37 PM GMT on November 11, 2015

...WEDNESDAY NOVEMBER 11 2015 7:40 AM EDT...
While racing northeastward across the northwestern Atlantic...Kate becomes the fourth hurricane of the 2015 Atlantic season this morning. Kate is expected to soon transition into a large and powerful non-tropical remnant gale that will threaten shipping interests in the Atlantic high seas. See special feature section below for additional details on Kate.

While weakening...upper vorticity in the Caribbean Sea has split into an upper trough in the western Caribbean Sea and another upper trough in the eastern Caribbean. An upper ridge has developed between the two upper troughs...with outflow from the upper ridge and upper divergence on the east side of the western Caribbean upper trough resulting in an increase in showers and thunderstorms across the southern Caribbean Sea. Surface tropical waves passing through the Caribbean may also be aiding this disturbed weather. Therefore the formation of a broad surface tropical low pressure will be possible in the southern Caribbean over the next couple of days. Computer models currently do not show tropical cyclone formation...perhaps beacause upper-level wind forecasts indicate the favorable upper ridge will shift westward over land (Central America) while the less favorable eastern Caribbean upper trough gradually takes its place over water by 96 hours.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0119Z-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...HURRICANE KATE...
Current Prognosis...As of 0600Z this early morning Kate was centered at 35.2N-67.5W...and while under the influence of an upper trough and surface 1006 mb frontal cyclone emerging from the eastern United States was racing northeastward across the open northwestern Atlantic to the north of Bermuda and to the south of Atlantic Canada. Despite the presence of very strong upper westerly winds across the tropical cyclone...Kate has been able to avoid getting sheared due to her fast northeast track that has allowed the surface center to keep up with the upper westerly wind speed. Coupled with supportive upper divergence on the east side of the aforementioned upper trough...this has allowed Kate to strengthen further into a minimal hurricane this morning.

Atmospheric Outlook for the Forecast Period...Kate will be controlled by the 1006 mb surface frontal cyclone and upper trough currently emerging from the eastern US during the forecast period. The frontal cyclone will continue to accelerate Kate northeastward while the upper trough will help transition Kate into a very strong non-tropical remnant gale supported by the upper divergence on the east side of the upper trough. With Kate reaching hurricane force this morning...she is now the dominant center of this mid-latitude system and therefore will absorb the frontal cyclone instead of the other way around. Therefore Kate will spend the next couple of days threatening the entire north Atlantic high seas as a strong remnant gale.

Thermodynamic Outlook for the Forecast Period...Kate has just crossed the 26 deg C isotherm into cooler waters...and therefore this will help aid in the weakening of Kate's vertical warm core and transition to non-tropical in the next 24 hours.


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

24 Hr Forecast (0600Z Nov 12)...75 mph maximum sustained wind non-tropical remnant gale centered at 39.5N-52.5W

Track Forecast...Kate is slightly northeast of my previous forecast track and so my updated one is adjusted accordingly.

Intensity Forecast...Kate is above my prevoius intensity forecast...and I show Kate maintaining hurricane force during the transition to non-tropical as Kate will continue to be supported by strong upper divergence on the east side of an upper trough as noted in the above atmospheric outlook section.

Impact Forecast...Impact swath is an extrapolation of the 4 AM EDT tropical storm wind field along my forecast track.

2015 Atlantic Hurricane Season Birdseye Discussion #127

By: NCHurricane2009, 9:27 AM GMT on November 10, 2015

...TUESDAY NOVEMBER 10 2015 4:30 AM EDT...
Tropical depression twelve becomes Tropical Storm Kate while just barely missing the western Bahamas. Kate is expected to accelerate northeastward into the western Atlantic and become absorbed by the frontal cyclone currently emerging from the southeastern United States. See special feature section below for additional details on Kate.

...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).

...SPECIAL FEATURE...TROPICAL STORM KATE...
Current Prognosis...As of 0600Z this early morning Tropical Storm Kate was accelerating northward and away from the western Bahamas while centered at 28.2N-76.5W. The tropical storm remains well-organized but appears to be under some light southwesterly shear with the central dense overcast biased to the east half of the center and curved outer bands biased to the north of the center.

Atmospheric Outlook for the Forecast Period...The upper trough currently over the southeastern US is supporting a developing frontal cyclone currently at 1016 mb over the coast of North Carolina. Kate will be controlled by this frontal cyclone and upper trough during the forecast period while they move into the western Atlantic. The frontal cyclone will accelerate Kate northeastward while the upper trough will increase the shear and help transition Kate into a non-tropical remnant low supported by the upper divergence on the east side of the upper trough. There is a high chance that the non-tropical remnants of Kate will lose its identity within the larger low pressure field of the frontal cyclone.

Thermodynamic Outlook for the Forecast Period...On the updated forecast track shown below...Kate will be crossing the 26 deg C isotherm into cooler waters by 24 hours...which (in addition to the shear mentioned in the above atmo outlook section) will aid in weakening this system and aid in transition to non-tropical.


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

24 Hr Forecast (0600Z Nov 11)...50 mph maximum sustained wind tropical storm centered at 34N-70W

48 Hr Forecast (0600Z Nov 12)...50 mph maximum sustained wind non-tropical remnant low centered at 37.5N-55W...becoming absorbed

Track Forecast...Kate is further north than previously forecast which causes a change in the forecast track. With Kate further north...she is now aligning with the southwesterly flow ahead of the developing western Atlantic frontal cyclone that will accelerate her faster and more northeastward such that she will now pass north of Bermuda (it was previously thought would stay south enough to align with the westerly flow on the south side of the frontal cyclone...which would have caused the track to bend more eastward into Bermuda).

Intensity Forecast...Kate remains on par with the intensity forecast shown in previous discussion #124 and therefore I have used that intensity forecast in my latest forecast.

Impact Forecast...Impact swath is an extrapolation of the 4 AM EDT tropical storm wind field along my forecast track.

2015 Atlantic Hurricane Season Birdseye Discussion #126 (Re-Post)

By: NCHurricane2009, 1:53 AM GMT on November 10, 2015

...MONDAY NOVEMBER 9 2015 12:40 AM EDT...
Tropical disturbance Invest 94-L becomes the twelvth tropical depression of the 2015 Atlantic Hurricane Season while moving northwestward toward the northwestern Bahamas. Tropical storm warnings have been raised in the Bahamas as the depression is likely to become a tropical storm in the next 24 hours. See special feature section below for additional details on this new tropical depression. Visit www.nhc.noaa.gov for up-to-the-minute latest information on this tropical cyclone.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0120Z-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 TWELVE...
Current Prognosis...As of 0000Z tropical depression twelve was centered just north of the southeastern Bahamas at 22.8N-72.5W. Apparently the tropical depression is under some light southerly shear as the swirl center has become exposed to the southwest of its curved thunderstorm bands.

Atmospheric Outlook for the Forecast Period...Conditions will be favorable for additional strengthening of this tropical cyclone over the next 24 hours due to low shear and upper divergence in the flow between the north side an upper vortex in the Caribbean and southwest side of the 1032 mb deep-layered ridge in the Atlantic. This flow is expected to quickly steer this tropical cyclone west-northwest into the northwest Bahamas over the next 24 hours where tropical storm warnings are currently in effect. After that time...what is now a south fragment of the central US upper trough will move into the western Atlantic while supporting a frontal cyclone...with this upper trough rapidly increasing the shear while the frontal cyclone turns this system northeastward toward Bermuda. At this time it is not expected that this system will reach Bermuda as a tropical cyclone as the shear will cause rapid weakening.

Thermodynamic Outlook for the Forecast Period...This system will be over waters above 26 deg C favorable for additional development for much of the forecast period. However on the forecast track shown below...this system will have crossed the 26 deg C isotherm into cooler waters by 72 hours...which (in addition to the shear mentioned in the above atmo outlook section) will aid in weakening this system by the end of the forecast period.


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

24 Hr Forecast (0000Z Nov 10)...50 mph maximum sustained wind tropical storm centered over the northwestern Bahamas at 25N-76.5W

48 Hr Forecast (0000Z Nov 11)...45 mph maximum sustained wind tropical storm centered at 29N-76.5W

72 Hr Forecast (0000Z Nov 12)...Sheared remnant low approaching Bermuda...centered at 31.5N-71W

Track Forecast...Tonight's 0000Z fix was slighlty west of my previous forecast track...and therefore my updated forecast track is a slight westward adjustment over my previous.

Intensity Forecast...Although this system is currently on par with my intensity forecast shown in discussion #124...my current intensity forecast is slightly below that one due to the fact that current satellite observations indicate that this system is already under some light southerly shear.

Impact Forecast...Satellite imagery shows that tropical depression twelve is a compact tropical cyclone...and so the impact swath in the above graphic shows the development of a tiny storm force wind field near the storm center for the part of the forecast where this system is expected to be at tropical storm strength.

2015 Atlantic Hurricane Season Birdseye Discussion #125

By: NCHurricane2009, 4:15 AM GMT on November 08, 2015

...SATURDAY NOVEMBER 7 2015 11:15 PM EDT...
The disturbance that was previously over the Lesser Antilles Islands has become better organized in the past 24 hours while passing over the Virgin Islands...Puerto Rico...and into the western Atlantic waters north of the Dominican Republic. The disturbance has been upgraded to Invest 94-L...and interests in the Bahamas should continue to monitor this system as it could become a tropical depression or storm as it moves into and across the islands in the next 48 hours. See special feature section below for additional details.

As expected...tropical disturbance Invest 93-L in the western Gulf of Mexico has succubmed to increasing westerly shear as the south side of a central US upper trough pushes toward the Gulf. Expect the remnants of the disturbance to become assimilated into the surface cold front associated with the upper trough and add to the rainfall along the front currently spreading across the southeastern US.

...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...SURFACE TROUGH INVEST 94-L...
Current Prognosis...As of 0000Z satellite animation and surface analysis from the NHC TAFB have positioned the surface trough of disturbance Invest 94-L in the Mona Passage between Puerto Rico and the Dominican Republic...with organized storm bands suggesting that the surface trough has a vorticity maximum just north of the Mona Passage that has moved from 19N-67.5W as of 0000Z to 19.5N-68W as of 0300Z. Because this disturbance has already moved westward to the Mona Passage...my updated forecast track below is shifted westward and now brings the system into the Bahamas instead of just northeast of the Bahamas (the early part of the track forecast is based on the currently obseved 0.5W longitude per 3 hour...or 4W longitude per 24 hour...progress). I have also lowered my intensity forecast as this system is not as well developed as I thought it would be by now.

Atmospheric Outlook for the Forecast Period...Conditions will be quiet favorable for tropical development of this disturbance over the next 48 hours due to low shear and upper divergence in the flow between the north side of the eastern Caribbean upper vortex and south side of the 1029 mb deep-layered ridge which has moved into the central Atlantic. This flow is expected to quickly steer this disturbance west-northwest into and across the Bahamas over the next 48 hours. After that time...what is now a south fragment of the central US upper trough will move into the western Atlantic while supporting a western Atlantic frontal cyclone...with this upper trough rapidly increasing the shear while the frontal cyclone turns this system northeastward toward Bermuda. At this time it is not expected that this system will reach Bermuda as a tropical cyclone as the shear will cause rapid weakening of whatever tropical cyclone forms out of this disturbance.

Thermodynamic Outlook for the Forecast Period...This system will be over waters well above 26 deg C favorable for tropical development for much of the forecast period. However on the forecast track shown below...this system will have crossed the 26 deg C isotherm into cooler waters by 96 hours...which (in addition to the shear mentioned in the above atmo outlook section) will aid in weakening this system by the end of the forecast period.

24 Hr Forecast (0000Z Nov 9)...Surface low centered over the southeastern Bahamas at 22.5N-72W

48 Hr Forecast (0000Z Nov 10)...45 mph maximum sustained wind tropical storm centered over the northwestern Bahamas at 25N-76W

72 Hr Forecast (0000Z Nov 11)...Sheared remnant low in the western Atlantic centered at 29N-76W

2015 Atlantic Hurricane Season Birdseye Discussion #124

By: NCHurricane2009, 6:34 AM GMT on November 07, 2015

...SATURDAY NOVEMBER 7 2015 1:36 AM EDT...
The cut-off upper trough over the eastern Caribbean Sea has evolved into a cut-off upper vortex due to the emergence of the 1028 mb deep-layered ridge from eastern North America and into the western Atlantic. The disturbed weather supported by the upper vortex has become better organized over and east of the Lesser Antilles due to a low shear and enhanced upper divergence environment between the northeast side of the upper vortex and south side of the deep-layered ridge...and I have upgraded this disturbance to a special feature on this blog. The disturbance has potential to bring enhanced rainfall to the northern Lesser Antilles...Virgin Islands...and Puerto Rico over the next 24 hours. Interests in the Bahamas should monitor this system as it could become a tropical storm by the time it reaches the eastern and central islands by 72 hours. See special feature section below for additional details on this disturbance.

The cut-off upper vortex and surface tropical wave that was previously moving into southeastern Mexico has arrived into the southwestern Gulf of Mexico while becoming upgraded to disturbance Invest 93-L. However there are no signs of additional tropical development...and unfavorable wind shear over the surface tropical wave will soon increase as the south side of the current central US upper trough advances toward the Gulf.

...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).

...SPECIAL FEATURE...SURFACE TROUGH APPROACHING THE LESSER ANTILLES...
Current Prognosis...Disturbed weather over and east of the Lesser Antilles islands continues due to upper divergence on the east side of what is now the cut-off upper vortex over the eastern Caribbean Sea. A surface tropical wave passing through this area has also enhanced this disturbance over the last 24 hours. This tropical wave is about to leave this disturbance while continuing to move into the eastern Caribbean Sea...with the disturbance becoming better organized around a surface trough currently located at 58W longitudde and supported by the upper divergence.

Atmospheric Outlook for the Forecast Period...Conditions will be quiet favorable for tropical development of this disturbance over the next 72 hours due to low shear and upper divergence in the flow between the north side of the eastern Caribbean upper vortex and 1028 mb deep-layered ridge. This flow is expected to quickly steer this disturbance west-northwest across the northern Lesser Antilles...Virgin Islands...and Puerto Rico over the next 36 hours...and then toward the eastern and central Bahamas by 72 hours. If any tropical cyclone forms during this time it will likely have its storm activity biased to the north half of the circulation due to the presence of the eastern Caribbean upper vortex just to the south. After 72 hours...what is now a south fragment of the central US upper trough will move into the western Atlantic while supporting a western Atlantic frontal cyclone...with this upper trough rapidly increasing the shear while the frontal cyclone turns this system northeastward toward Bermuda. At this time it is not expected that this system will reach Bermuda as a tropical cyclone as the shear will cause rapid weakening of whatever tropical cyclone forms out of this disturbance.

Thermodynamic Outlook for the Forecast Period...This system will be over waters well above 26 deg C favorable for tropical development for much of the forecast period. However on the forecast track shown below...this system will have crossed the 26 deg C isotherm into cooler waters by 120 hours...which (in addition to the shear mentioned in the above atmo outlook section) will aid in weakening this system by the end of the forecast period.

24 Hr Forecast (0000Z Nov 8)...Surface low centered over the northern Lesser Antilles at 17.5N-63W

48 Hr Forecast (0000Z Nov 9)...35 mph maximum sustained wind tropical depression centered just north of the Dominican Republic and just east of the Bahamas at 21.5N-70W

72 Hr Forecast (0000Z Nov 10)...60 mph maximum sustaiend wind tropical storm centered just east of the central Bahamas at 24N-74W

96 Hr Forecast (0000Z Nov 11)...50 mph maximum sustained wind tropical storm centered in the western Atlantic at 29N-74W

120 Hr Forecast (0000Z Nov 12)...Sheared remnant low centered southwest of Bermuda at 31.5N-69W

2015 Atlantic Hurricane Season Birdseye Discussion #123

By: NCHurricane2009, 1:57 AM GMT on November 06, 2015

...THURSDAY NOVEMBER 5 2015 8:57 PM EDT...
The Atlantic continues to be characterized by a mid-latitude longwave upper trough and a cut-off upper vortex over the Lesser Antilles and eastern Caribbean Sea. Recently the 1028 mb deep-layered ridge emerging from eastern North America has caused a southwestern fragment of the longwave upper trough to become cut-off and merge with the eastern Caribbean upper vortex...resulting in an elongated north-south cut-off upper trough currently positioned from Bermuda to the eastern Caribbean. Divergence on the east side of this cut-off upper trough is inducing a surface trough in the area along with showers and thunderstorms...with a weak and poorly-defined tropical wave also currently moving into the area of showers and thunderstorms. By 72 hours the deep-layered ridge will be passing north of the cut-off upper trough...with an area of favorable lower shear and upper divergence between the northeast side of the cut-off upper trough and south side of the deep-layered ridge potentially causing tropical development of this disturbance when it arrives into the western Atlantic to the north of Puerto Rico. Currently the only major computer model that most aggressively shows this solution is the usually overly-agressive CMC model...therefore not upgrading this disturbance to a special feature on this blog until additional models show support or until this disturbance shows signs of development.

Yet another cut-off upper vortex has been moving westward across the Caribbean Sea on the south side of the 1028 mb deep-layered ridge emerging from eastern North America. This cut-off upper vortex has recently made landfall in southeastern Mexico from the western Caribbean...and a surface tropical wave moving westward in tandem with this upper vortex has become better organized while taking advantage of favorable low shear and upper divergence between the northeast side of the upper vortex and south side of the deep-layered ridge. However this tropical wave will soon be making landfall in southeastern Mexico...and development later on as this wave moves into the southwestern Gulf of Mexico is likely to be precluded by westerly shear as the south side of the current central US upper trough advances into the Gulf. In addition computer models do not forecast this tropical wave to develop.

...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.

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).

2015 Atlantic Hurricane Season Birdseye Discussion #122

By: NCHurricane2009, 2:01 AM GMT on November 05, 2015

...WEDNESDAY NOVEMBER 4 2015 9:01 PM EDT...
The National Hurricane Center identifies a risk area for tropical development in the western Atlantic in their 5-day tropical weather outlook...resuming daily updates on this blog...

The western Atlantic is currently characterized by a mid-latitude longwave upper trough offshore of North America and a cut-off upper vortex over the Lesser Antilles. As the 1028 to 1029 mb deep-layered ridge currently over eastern North America moves offshore over the next 72 hours...a southwestern fragment of the longwave upper trough is expected to become cut-off and merge with the upper vortex over the Lesser Antilles. By 96 hours an area of upper divergence between the northeast side of the enlarged upper vortex and south side of the deep-layered ridge could trigger a surface tropical disturbance north of Puerto Rico in the western Atlantic. Currently the only major computer model that most aggressively shows this solution is the NAVGEM model...therefore not declaring a special feature on this blog until additional models show support or until this disturbance shows signs of development as it forms.

...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).


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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