NCHurricane2009's Blog

2015 Atlantic Hurricane Season Birdseye Discussion #121

By: NCHurricane2009, 1:01 AM GMT on October 30, 2015

...THURSDAY OCTOBER 29 2015 9:01 PM EDT...
Divergence on the east side of a longwave upper trough in the eastern Atlantic has enhanced the showers and thunderstorms of a surface tropical wave currently located southwest of the islands of the Repbublic of Cabo Verde. The upper divergence has also supported surface pressure drops such that the tropical wave has developed a 1010 mb low pressure spin...and as a result the tropical wave has become introduced into the National Hurricane Center tropical weather outlook. The tropical wave is expected to accelerate westward under the influence of the 1029 mb Atlantic surface ridge marked in the atmospheric features chart below while the south side of the eastern Atlantic upper trough cuts off and produces upper westerlies opposing the forward travel of the tropical wave. Therefore wind shear is expected to prevent tropical cyclone formation of this tropical wave. This is my final update on the Atlantic tropics for now unless the situation changes with this tropical wave...or unless the threat of tropical activity pops up elsewhere in the Atlantic basin.

...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 #120A (Special Update)

By: NCHurricane2009, 2:16 AM GMT on October 22, 2015

...WEDNESDAY OCTOBER 21 2015 10:15 PM EDT...
Although a frontal disturbance with slight tropical potential is currently developing southeast of Bermuda as expected...a frontal cyclone currently moving across the Great Lakes region of North America will soon move into the northwestern Atlantic and quickly absorb this disturbance. Therefore the Atlantic tropics are quiet and I have ceased doing daily updates on this blog. Will resume daily updates on this blog when the threat of tropical activity returns to the Atlantic basin.

2015 Atlantic Hurricane Season Birdseye Discussion #120

By: NCHurricane2009, 12:18 PM GMT on October 21, 2015

...WEDNESDAY OCTOBER 21 2015 8:17 AM EDT...
The eastern Pacific portion of southeastern Mexico tropical disturbance Invest 92-L has become Tropical Storm Patricia. The low-level inflow of Patricia is dominating the area and therefore the remaining southwestern Gulf of Mexico portion of the disturbance has become inactive and is not expected to develop.

The southern part of the longwave upper trough currently moving into the western Atlantic from eastern North America will cut-off into an upper vortex over the next couple of days. Meanwhile a large lobe of low surface pressure is present southeast of Bermuda...consisting of a cold front...supported by divergence on the southeast side of the longwave upper trough. This lobe of low surface pressure has the potential to evolve into a tropical or subtropical disturbance supported by the aforementioned forecast cut-off upper vortex...at a location to the southeast of Bermuda in the next 24 to 48 hours. However the latest computer model runs suggest a high chance that this disturbance will become quickly absorbed by the 1011 mb frontal depression currently over the northwestern US when this depression moves into the northwestern Atlantic.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

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

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 #119 (2nd Release)

By: NCHurricane2009, 10:39 AM GMT on October 20, 2015

**This is a second release of discussion #119 which now contains updated charts**

...TUESDAY OCTOBER 20 2015 6:39 AM EDT...
Tropical disturbance Invest 92-L over the western Caribbean...northern Central America...southeastern Mexico...and southwestern Gulf of Mexico continues to lack an offshore surface circulation and currently consists of a pair of surface troughs. The west side of the current 1031 mb central US ridge...followed by a second central US ridge to develop beneath the back side of the upper trough currently making landfall in western Canada...will eventually push the disturbance northward across the western Gulf...eastern Mexico...and into southeastern Texas over the next few days. With a favorable upper ridge expected to persist over the tropical disturbance...tropical cyclone formation is possible in the western Gulf over the next few days. Regardless of tropical cyclone formation or not...enhanced rainfall with flooding potential will spread from northern Central America and southeastern Mexico and toward northeastern Mexico and southeastern Texas over the next days.

The southern part of the longwave upper trough currently departing eastern North America has potential to cut-off into an upper vortex over the next few days. Meanwhile a large lobe of low surface pressure is present southeast of Bermuda...consisting of a cold front and surface trough...supported by divergence on the southeast side of the longwave upper trough. This lobe of low surface pressures has the potential to evolve into a tropical or subtropical disturbance supported by the aforementioned forecast cut-off upper vortex...at a location to the southeast of Bermuda in 2 to 3 days. However the latest computer model runs suggest a high chance that this disturbance will become quickly absorbed by a northwestern Atlantic frontal cyclone that will be supported by the upper trough that is currently making landfall in western Canada.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0126Z-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 #119

By: NCHurricane2009, 9:04 AM GMT on October 20, 2015

**Currently dealing with technical difficulties updating the atmospheric and thermodynamic outlook charts from my previous update. I am releasing this blog update for now and may update the charts later on**

...TUESDAY OCTOBER 20 2015 5:05 AM EDT...
Tropical disturbance Invest 92-L over the western Caribbean...northern Central America...southeastern Mexico...and southwestern Gulf of Mexico continues to lack an offshore surface circulation and currently consists of a pair of surface troughs. The west side of the current 1031 mb central US ridge...followed by a second central US ridge to develop beneath the back side of the upper trough currently making landfall in western Canada...will eventually push the disturbance northward across the western Gulf...eastern Mexico...and into southeastern Texas over the next few days. With a favorable upper ridge expected to persist over the tropical disturbance...tropical cyclone formation is possible in the western Gulf over the next few days. Regardless of tropical cyclone formation or not...enhanced rainfall with flooding potential will spread from northern Central America and southeastern Mexico and toward northeastern Mexico and southeastern Texas over the next days.

The southern part of the longwave upper trough currently departing eastern North America has potential to cut-off into an upper vortex over the next few days. Meanwhile a large lobe of low surface pressure is present southeast of Bermuda...consisting of a cold front and surface trough...supported by divergence on the southeast side of the longwave upper trough. This lobe of low surface pressures has the potential to evolve into a tropical or subtropical disturbance supported by the aforementioned forecast cut-off upper vortex...at a location to the southeast of Bermuda in 2 to 3 days. However the latest computer model runs suggest a high chance that this disturbance will become quickly absorbed by a northwestern Atlantic frontal cyclone that will be supported by the upper trough that is currently making landfall in western Canada.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0126Z-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 #118

By: NCHurricane2009, 1:30 AM GMT on October 19, 2015

...SUNDAY OCTOBER 18 2015 9:32 PM EDT...
The 1034 mb surface ridge currently over the central US pushes the low pressure center of large tropical disturbance Invest 92-L westward into southeastern Mexico...with the disturbance currently covering northern Central America...southeastern Mexico...the western Caribbean...and southwestern Gulf of Mexico. The west side of the current central US ridge...followed by a second central US ridge to develop beneath the back side of the upper trough currently offshore of western Canada...will eventually push the disturbance northward across the western Gulf...eastern Mexico...and into southeastern Texas over the next five days. With a favorable upper ridge expected to persist over the tropical disturbance...tropical cyclone formation is possible in the western Gulf over the next few days. So far the disturbance has not developed an offshore circulation to be considered a special feature on this blog. Regardless of tropical cyclone formation or not...enhanced rainfall with flooding potential will spread from northern Central America and southeastern Mexico and toward northeastern Mexico and southeastern Texas over the next days.

The southern part of the longwave upper trough over eastern North America has potential to cut-off into an upper vortex over the next few days. Meanwhile a northeastern lobe of the large surface low pressure field of 92-L is currently entangled with surface troughs and fronts across Florida...the Bahamas...and western Atlantic to the south of Bermuda supported by divergence on the southeast side of the longwave upper trough. This lobe of low surface pressures has the potential to evolve into a tropical or subtropical disturbance supported by the aforementioned forecast cut-off upper vortex...at a location to the south of Bermuda and north of the Caribbean Islands in 3 to 4 days. However the latest computer model runs suggest an increasing chance that this disturbance will become quickly absorbed by a northwestern Atlantic frontal cyclone that will be supported by the upper trough that is currently located offshore of western Canada.

...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).

2015 Atlantic Hurricane Season Birdseye Discussion #117

By: NCHurricane2009, 5:36 AM GMT on October 18, 2015

...SUNDAY OCTOBER 18 2015 1:37 AM EDT...
The 1032 mb surface ridge currently over the central US pushes the low pressure center of large tropical disturbance Invest 92-L westward into Belize and Guatemala...with the disturbance currently covering parts of the eastern Pacific...Central America...southeastern Mexico...the western Caribbean...and the southern Gulf of Mexico. The central US ridge will eventually push the disturbance into the western Gulf of Mexico. With a favorable upper ridge expected to persist over the tropical disturbance...tropical cyclone formation is possible in the western Gulf over the next few days. Waiting to see how organized this disturbance is when it enters the western Gulf before considering an upgrade to a special feature on this blog. Regardless of tropical cyclone formation or not...enhanced rainfall with flooding potential is possible across southeastern Mexico...Central America...and western Cuba.

The southern part of the longwave upper trough over eastern North America has potential to cut-off into an upper vortex over the next few days...with potential for the northeastern lobe of the large surface low pressure field of Invest 92-L to become enhanced by upper divergence on the east side of the upper vortex and evolve into a tropical or subtropical disturbance to the south of Bermuda and north of the Caribbean Islands by days 4 or 5.

...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 #116

By: NCHurricane2009, 6:06 AM GMT on October 17, 2015

...SATURDAY OCTOBER 17 2015 2:06 AM EDT...
The tropical disturbance in the western Caribbean has become re-enforced by the tropical wave currently passing through and by a cold front that has been driven into the southeastern Gulf of Mexico by the longwave upper trough regime over eastern North America. The disturbance has developed a broad 1008 mb low pressure spin centered just east of Belize and as a result has been upgraded to Invest 92-L on the Naval Research Laboratory (NRL) site of the US Navy...and has become introduced into the National Hurricane Center (NHC) tropical weather outlook. The 1034 mb surface ridge currently over the central US is being supported by western upper-level convergence of the aforementioned longwave upper trough...and is driving the disturbance westward into central America and southeastern Mexico...and will eventually push the disturbance into the western Gulf of Mexico. With a favorable upper ridge expected to persist over the tropical disturbance...tropical cyclone formation is possible in the western Gulf over the next few days. Waiting to see how organized this disturbance is when it enters the western Gulf before upgrading it to a special feature on this blog. Regardless of tropical cyclone formation or not...enhanced rainfall with flooding potential is possible across southeastern Mexico...northern Central America...western Cuba...and perhaps as far northeast as south Florida.

The southern part of the longwave upper trough over eastern North America has potential to cut-off into an upper vortex over the next few days...with potential for the northeastern lobe of the large surface low pressure field of the western Caribbean disturbance to become enhanced by upper divergence on the east side of the upper vortex and evolve into a tropical or subtropical disturbance to the south of Bermuda and north of the Caribbean Islands by day 5.

...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).

2015 Atlantic Hurricane Season Birdseye Discussion #115

By: NCHurricane2009, 5:23 AM GMT on October 16, 2015

...FRIDAY OCTOBER 16 2015 1:23 AM EDT...
A significant tropical disturbance is developing in the western Caribbean as a tropical wave coming in from the east has merged with the surface trough in the region that continues to be supported by favorable low shear/enhanced upper outflow of the upper ridge in the area. Meanwhile a longwave upper trough regime is currently present over eastern North America...with western upper-level convergence of this regime supporting a strong 1034 mb ridge currenlty over Montana that will drive this tropical disturbance across the Yucatan Peninsula and into the western Gulf of Mexico over the next five days. With the favorable upper ridge expected to persist over the tropical disturbance...tropical cyclone formation is possible in the western Gulf 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 0132Z-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 #114

By: NCHurricane2009, 1:28 AM GMT on October 15, 2015

...WEDNESDAY OCTOBER 14 2015 9:30 PM EDT...
A surface trough persists in the western Caribbean Sea under a favorable upper ridge. The CMC and NAVGEM models which continue to be the biggest proponents in predicting development of this surface trough currently predict the development of a significant tropical disturbance in 72 to 96 hours when the tropical wave currently in the eastern Caribbean reaches and merges with this surface trough.

...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 #113

By: NCHurricane2009, 3:31 AM GMT on October 14, 2015

...TUESDAY OCTOBER 13 2015 11:31 PM EDT...
A surface trough has developed in the western Caribbean Sea...as surface pressures drop due to poleward upper outflow from a more favorable upper ridge developing over the area and into the cut-off upper trough over the southeastern US coast and Gulf of Mexico (recently this upper trough is no longer cut-off while merging with a strong upper trough over eastern Canada). The surface low pressure fields of the tropical wave that has recently moved into the eastern Pacific from the western Caribbean...and the tail end of the cold front tied to the cut-off upper trough...may have also contributed to the surface trough. The CMC and NAVGEM models which have been the biggest proponents in predicting development of this surface trough currently predict tropical cyclone formation at 96 hours when the tropical wave currently in the eastern Caribbean reaches and enhances this surface trough. Therefore will continue to do daily blog updates due to the continued potential for tropical development in the western Caribbean in the coming days.

The upper trough currently moving into the northeast Atlantic from the north-central Atlantic is forecast to cut-off into an upper vortex in the vicinity of the Azores and Canary Islands in about 48 hours. The latest computer model runs suggest that the surface low to develop with the support of the upper vortex will stay north enough of the 26 deg C sea surface temperature isotherm such that subtropical cyclone development is not expected...and therefore this is the final time I will mention this system on this blog unless this situation changes again.

...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 #112

By: NCHurricane2009, 2:18 AM GMT on October 13, 2015

...MONDAY OCTOBER 12 2015 10:18 PM EDT...
A cut-off upper trough persists over the southeastern US coast and Gulf of Mexico. The decaying cold front tied to this cut-off upper trough has reached the northwestern Caribbean. Upper-level winds could become increasingly favorable for the development of a tropical disturbance from the weather currently being triggered by the decaying front and tropical wave presently in the western Caribbean after 48 hours when the cut-off upper trough becomes replaced by more favorable upper ridging.

The upper trough currently in the north-central Atalntic is forecast to cut-off into an upper vortex in the northeastern Atlantic in the vicinity of the Azores and Canary Islands in about 72 hours. The latest computer models suggest that the surface low to develop with the support of the upper vortex will stay north enough of the 26 deg C sea surface temperature isotherm such that subtropical cyclone development appears less likely.

...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).

2015 Atlantic Hurricane Season Birdseye Discussion #111

By: NCHurricane2009, 1:38 AM GMT on October 12, 2015

...SUNDAY OCTOBER 11 2015 9:39 PM EDT...
The southern part of the upper trough that has recently emerged from eastern North America has evolved into a cut-off upper vortex currently centered over the southeastern US coast. The cold front tied to this cut-off upper vortex is slowly shifting southeast toward the western Caribbean...with conditions becoming increasingly favorable for the development of a tropical disturbance triggered by the front after 72 hours when the cut-off upper vortex becomes replaced by more favorable upper ridging.

The northern part of the upper trough that has recently emerged from eastern North America is forecast to cut-off into an upper vortex in the northeastern Atlantic in the vicinity of the Azores and Canary Islands in about 96 hours. Despite sea-surface temperatures just below 26 deg C in this region...cold temperatures of the upper vortex could create enough instability to support the formation of a surface subtropical system.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1916Z-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 #110

By: NCHurricane2009, 5:04 AM GMT on October 11, 2015

...SUNDAY OCTOBER 11 2015 1:10 AM EDT...
Resuming daily updates on this blog with the potential for two tropical disturbances to emerge from the upper trough currently over eastern North America over the coming days:

The southern part of the upper trough over eastern North America is expected to cut-off over the southwestern Atlantic and Gulf of Mexico over the next 72 hours. The cold front tied to this upper trough will likely dive southeast into the western Caribbean...with conditions becoming increasingly favorable for the development of a tropical disturbance triggered by the front after 96 hours when the cut-off upper trough becomes replaced by more favorable upper ridging.

The northern part of the upper trough over eastern North America is currently forecast to cut-off into an upper vortex in the northeastern Atlantic in the vicinity of the Azores and Canary Islands in about five days. Despite sea-surface temperatures just below 26 deg C in this region...cold temperatures of the upper vortex could create enough instability to support the formation of a surface subtropical system.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1914Z-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 #109A (Special Update)

By: NCHurricane2009, 11:57 AM GMT on October 08, 2015

...THURSDAY OCTOBER 8 2015 7:55 AM EDT...
As expected...Joaquin overnight has transitioned into a remnant non-tropical gale supported by divergence on the east side of a shortwave upper trough in the jet stream while moving into the northeastern Atlantic. Gusty winds from the remnant low are expected in the northwestern Azores this morning. The remnant low will move into Spain and Portugal over the next couple of days while weakening due to upper convergence on the east side of an upper ridge currently in the northeast Atlantic.

In the wake of Joaquin...the Atlantic tropics are quiet. Therefore I have stopped doing daily updates on this blog until the threat of tropical activity returns to the Atlantic basin.

2015 Atlantic Hurricane Season Birdseye Discussion #109

By: NCHurricane2009, 3:22 AM GMT on October 07, 2015

...TUESDAY OCTOBER 6 2015 11:22 PM EDT...
Hurricane Joaquin accelerating eastward into the Atlantic high seas and is expected to transition into a non-tropical remnant gale that will threaten shipping interests in the region over the next couple of days. See special feature section below for more details on Joaquin. Continue to visit www.nhc.noaa.gov for up to the minute latest information on Joaquin.

Tropical wave Invest 91-L has become weak and poorly-organized due to southerly vertical shear on the east side of a TUTT (Tropical Upper Tropospheric Trough...marked by blue-dashed line and blue L to the left of 91-L in the atmospheric features chart below). Tropical cyclone formation is not expected.

...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.

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 JOAQUIN...
Current Prognosis...Despite entering the high-latitude westerly jet stream curently in the north Atlantic...Joaquin's fast eastward acceleration has allowed the storm center to keep up with the upper-level wind speed such that the hurricane so far has avoided getting sheared apart by the jet...as evidenced by spiral thunderstorm bands around the center remaining symmetrically distributed. As a result Joaquin has maintained category 1 strength over the past 24 hours. As of 0000Z earlier this evening the center of the hurricane was over the northwest Atlantic at 39.5N-54.5W.

Atmospheric Outlook for the Forecast Period...Joaquin is bending eastward in track and accelerating while reaching the high-latitude westerly jet stream in the north Atlantic...but with the observations in the above current prognosis it appears the forward speed of the storm will be sufficient such that Joaquin will not be too badly sheared by the jet. Coupled with the fact that there is a shortwave upper trough in the jet (marked by blue-dashed line just left of Joaquin the above atmospheric features chart)...only slow weakening is anticipated as Joaquin transitions into a non-tropical remnant gale supported by divergence on the east side of the shortwave.

Thermodynamic Outlook for the Forecast Period...Joaquin is crossing the 26 deg C isotherm into cooler waters which will aid in the transition to non-tropical in the next 24 hours.


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

24 Hr Forecast (0000Z Oct 8)...60 mph maximum sustained wind non-tropical remnant low northwest of the Azores centered at 41.5N-37.5W

Track Forecast...Tonight's 0000Z fix indicates the hurricane is slightly southeast of my previous forecast track...and so my updated track is adjusted accordingly.

Intensity Forecast...Because Joaquin is slightly stronger than my previous forecast...and because the hurricane does not appear to be getting sheared by the jet stream its embedded within (as noted in the above current prognosis and atmo outlook section)...I have raised my intensity forecast.

Impact Forecast...Impact swath in the above graphic is an extrapolation of the current 11 PM EDT NHC tropical storm wind field along my forecast track. I no longer shrink the size of the swath depsite the forecast weakening as it appears Joaquin's wind field size is being expanded/maintained by surface pressure drops induced by divergence on the east side of the shortwave upper trough mentioned in the above atmo outlook section.

2015 Atlantic Hurricane Season Birdseye Discussion #108

By: NCHurricane2009, 4:26 AM GMT on October 06, 2015

...TUESDAY OCTOBER 6 2015 12:26 AM EDT...
Hurricane Joaquin getting ready to turn eastward into the Atlantic high seas from the northwestern Atlantic. See special feature section below for more details on Joaquin. Continue to visit www.nhc.noaa.gov for up to the minute latest information on Joaquin.

Vigorous tropical wave Invest 91-L in the central tropical Atlantic has not become better organized. Therefore tropical cyclone formation is not likely before it encounters less favorable southerly vertical shear on the east side of a TUTT (Tropical Upper Tropospheric Trough...marked by blue-dashed line and blue L to the left of 91-L in the atmospheric features chart below). I have cancelled 91-L as a special feature on this blog.

...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...HURRICANE JOAQUIN...
Current Prognosis...Wind shear over Hurricane Joaquin remains relaxed as evidenced by spiral thunderstorm bands around the center remaining symmetrically distributed. As a result Joaquin has maintained category 1 strength over the past 24 hours. As of 0000Z earlier this evening the center of the hurricane was over the northwest Atlantic at 36.2N-63.8W.

Atmospheric Outlook for the Forecast Period...The current northeast track of the hurricane is expected to bend more eastward in the next 24 to 48 hours as Joaquin reaches the high-latitude westerly jet stream in the north Atlantic...with strong upper-level winds in the jet stream to also shear apart the storm.

Thermodynamic Outlook for the Forecast Period...On the current forecast track Joaquin will cross the 26 deg C isotherm into cooler waters by 24 hours which will help Joaquin weaken to a remnant low by the end of the forecast period.


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

24 Hr Forecast (0000Z Oct 7)...65 mph maximum sustained wind tropical storm centered at 40N-55W

48 Hr Forecast (0000Z Oct 8)...50 mph maximum sustained wind remnant low northwest of the Azores centered at 42.5N-38W

Track Forecast...Tonight's 0000Z fix indicates the hurricane is essentially on the previous forecast track and so I have made no changes to my forecast track.

Intensity Forecast...Even though Joaquin is a bit stronger than my previous intensity forecast...I currently expect wind shear and cooler waters to begin weakening the storm by 24 hours and therefore have made no changes to my intensity forecast.

Impact Forecast...Impact swath in the above graphic is an extrapolation of the current 11 PM EDT NHC tropical storm wind field along my forecast track...with shrinkage in the swath for the later part of the forecast where Joaquin is forecast to weaken.

2015 Atlantic Hurricane Season Birdseye Discussion #107

By: NCHurricane2009, 5:56 AM GMT on October 05, 2015

...MONDAY OCTOBER 5 2015 1:57 AM EDT...
Hurricane Joaquin's east side strikes Bermuda with tropical storm conditions. As the hurricane continues north-northeast...conditions in Bermuda should improve through the morning hours. See special feature section below for more details on Joaquin. Continue to visit www.nhc.noaa.gov for up to the minute latest information on Joaquin.

Surface low Invest 90-L located southeast of Bermuda remains stationary and continues to not show signs of tropical development. Conditions will become hostile for 90-L to develop as Hurricane Joaquin's outflow begins to overspread and shear 90-L...and therefore tropical cyclone formation is no longer expected. Expect 90-L to gradually lose its identity on the southeast side of Joaquin's low-level circulation over the next two to three days.

Showers and thunderstorms have become better organized with the vigorous eastern Atlantic tropical wave located to the southwest of the islands of the Republic of Cabo Verde. As a result this tropical wave has been upgraded to tropical disturbance Invest 91-L and has potential for tropical cyclone formation over the next few days. See second special feature section below for more details on 91-L. Interests in the northeastern Caribbean Islands should monitor 91-L over the next few days.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1200Z and 1335Z-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 JOAQUIN...
Current Prognosis...Wind shear over Hurricane Joaquin has relaxed as the shearing western Atlantic upper vortex has been flung westward and away into the NW-SE oriented upper trough over the southeastern US in a Fujiwhara-like interaction with the hurricane. Further evidence of reduced shear is that the spiral thunderstorm bands around the eye have become more symmetrically distributed. Despite the improving atmospheric conditions for Joaquin (due to the reduced shear)...satellite has shown the thunderstorm bands weakening and breaking up a bit...and aircraft reconaissance has indicated a steady weakening to category 1...all perhaps due to dry air ingestion (source of this dry air is mentioned in the thermodynamic outlook section below). As of 0000Z earlier this evening the eye of the hurricane passed over 32.5N-65.8W...a location just west of Bermuda with the eastern rain bands of the hurricane producing tropical storm force winds over the island.

Atmospheric Outlook for the Forecast Period...While in a Fujiwhara-like interaction with a western Atlantic upper vortex...the hurricane has arced more northward in its northeast track. What is left of this upper vortex is marked by a blue-dashed line just left of Joaquin in the above atmospheric features chart...and has merged with the NW-SE tilted upper trough over the southeastern US to create a massive upper vortex centered over northeast Florida (marked by blue L). The current north-northeast track is expected to bend more eastward at 48 and 72 hours when Joaquin reaches the high-latitude westerly jet stream in the north Atlantic...with strong upper-level winds in the jet stream to also shear apart the storm.

Thermodynamic Outlook for the Forecast Period...Joaquin is currently over 28 deg C waters favorable for tropical development...but on the current forecast track should cross the 26 deg C isotherm into cooler waters by 48 hours which will help Joaquin weaken to a remnant low by the end of the forecast period. In the short-term additional weakening may be possible due to ingestion of a large dry air mass to the southwest (seen in the above thermodynamics chart). This large mass of dry air has its origin in upper-level convergence on the west side of the NW-SE tilted upper trough over the SE US...which has become flung eastward toward the hurricane in the westerly flow on the south side of large upper vortex currenlty over NE Florida (mentioned in the above atmospheric outlook section).


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

24 Hr Forecast (0000Z Oct 6)...75 mph maximum sustained wind hurricane centered at 36N-64W

48 Hr Forecast (0000Z Oct 7)...65 mph maximum sustained wind tropical storm centered at 40N-55W

72 Hr Forecast (0000Z Oct 8)...50 mph maximum sustained wind remnant low northwest of the Azores centered at 42.5N-38W

Track Forecast...Tonight's 0000Z fix and current north-northeast heading indicates Joaquin is slightly west of my previous track forecast...and therefore my updated forecast track points are adjusted slightly westward accordingly.

Intensity Forecast...With Joaquin currently lower than my previous intensity forecast...I have adjusted my updated intensity forecast accordingly.

Impact Forecast...Impact swath in the above graphic is an extrapolation of the current 11 PM EDT NHC tropical storm wind field along my forecast track...with shrinkage in the swath for the later part of the forecast where Joaquin is forecast to weaken.

...SPECIAL FEATURE...TROPICAL WAVE INVEST 91-L...
Current Prognosis...Showers and thunderstorms associated with the tropical wave southwest of the islands of the Republic of Cabo Verde have become better organized around a 1010 mb tropical low pressure spin and as a result the tropical wave has been upgraded to tropical disturbance Invest 91-L. 91-L is likely to continue to organize in the next 24 hours while in an environment of low shear and enhanced upper outflow beneath a tropical upper ridge in the central tropical Atlantic (marked by blue-zig-zag line over 91-L) in the above atmospheric features chart). The low pressure spin of the tropical wave was centered at 9.5N-39.5W as of 0000Z...and was at 10N-40.5W as of 0300Z. My track forecast below is initialized based on the 1W longitude per 3 hour (or 8W longitude per 24 hour) progress.

Atmospheric Outlook for the Forecast Period...91-L is likely to continue west-northwest during the forecast period as the western Atlantic ridge weakness associated with Hurricane Joaquin and 1001 mb frontal gale over the coastal Carolinas fills while both features move northward. 91-L will run into less favorable upper winds in the mid to later part of the forecast period...at first dealing with southerly vertical shear from the TUTT (Tropical Upper Tropospheric Trough) currently just east of the Lesser Antilles (marked by blue L and blue-dashed line in the above atmospheric features chart). However this shear is not expected to be severe as the TUTT will be in the process of dissipating. Shear will be more severe at the end of the forecast period (120 hours) as the upper vortex currently over northeastern Florida leaves behind an upper trough in the central Caribbean region.

Thermodynamic Outlook for the Forecast Period...91-L will be embedded in a favorable moist enviornment and over 29 to 30 deg C waters that will aid in tropical development.

24 Hr Forecast (0000Z Oct 6)...Tropical low centered at 11N-47.5W

48 Hr Forecast (0000Z Oct 7)...35 mph maximum sustained wind tropical depression centered at 12.5N-54W

72 Hr Forecast (0000Z Oct 8)...35 mph maximum sustained wind tropical depression under southerly vertical shear moving into the Lesser Antilles centered at 15N-60W

96 Hr Forecast (0000Z Oct 9)...35 mph maximum sustained wind tropical depression under southerly vertical shear centered just southeast of Puerto Rico at 17.5N-66W

120 Hr Forecast (0000Z Oct 10)...Remnant tropical wave over the Dominican Republic at 71W longitude

2015 Atlantic Hurricane Season Birdseye Discussion #106

By: NCHurricane2009, 4:38 AM GMT on October 04, 2015

...SUNDAY OCTOBER 4 2015 12:38 AM EDT...
Hurricane Joaquin regains category 4 strength...and is expected to directly and severely strike Bermuda as a category 2 or 3 hurricane in the next 24 hours. Therefore preparations in Bermuda should be rushed to completion now if they are not complete. See special feature section below for more details on Joaquin. Continue to visit www.nhc.noaa.gov for up to the minute latest information on Joaquin.

Surface low Invest 90-L located southeast of Bermuda has stalled...which will give it more time to develop before Hurricane Joaquin absorbs it. See second special feature section below for more details on 90-L.

Showers and thunderstorms have increased in association with an eastern Atlantic tropical wave located to the southwest of the islands of the Republic of Cabo Verde. Conditions are currently unfavorable for development due to a shear-inducing southward-digging upper trough being delivered by the 998 mb deep-layered cyclonic gale currently near the Azores. However by 48 to 72 hours this tropical wave could find more favorable upper winds as it moves into the central tropical Atlantic beneath an expanding tropical upper ridge to develop in the wake of the upper trough. Currently not considering this tropical wave as a special feature on this blog until I see how well-organized it is when it gets exposed to the more favorable upper winds.

...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).

...SPECIAL FEATURE...MAJOR HURRICANE JOAQUIN...
Current Prognosis...Aircraft reconaissance this past afternoon found that Joaquin re-strengthened into a category 4 hurricane...and in fact was stronger than ever with 155 mph maximum sustained winds...making the hurricane just shy of category 5. It appears this unexpected burst of intensification was due to the completion of an eye wall replacment cycle right when the hurricane was in an upper divergence maximum between southeasterlies on the east side of the northwest-southeast tilted upper trough over the southeastern US (marked by blue-dashed line west of Joaquin the above atmopsheric features chart)...and upper southwesterlies on the south side of the western Atlantic upper vortex (marked by blue-dashed line north of Joaquin). Since then...the hurricane has resumed a weakening trend (latest aircraft reconaissance tonight measured lower 130 mph winds in the eye) while entering shearing westerly winds on the south side of the western Atlantic upper vortex that have pushed most of the thunderstorms to the east of the eye. As of 0000Z earlier this evening the eye of the hurricane passed over 27.5N-69.5W while continuing to acclerate northeastward toward Bermuda.

Atmospheric Outlook for the Forecast Period...A western Atlantic upper vortex (marked by blue-dashed line to the north of Joaquin in the above atmospheric features chart) will steer Joaquin northeastward toward Bermuda in the next 24 hours. The westerly shear Joaquin is currently experiencing on the south side of the upper vortex will relax at 24 and 48 hours as the upper vortex will shift away while getting flung westward in a fujiwhara-like interaction with Joaquin. By 72 and 96 hours Joaquin should reach the high-latitude westerly jet stream in the north Atlantic which will surely turn Joaquin eastward while shearing apart the storm.

Thermodynamic Outlook for the Forecast Period...Joaquin is currently over 29 to 30 deg C waters very favorable for tropical development...but on the current forecast track should cross the 26 deg C isotherm into cooler waters by 72 hours which will help Joaquin weaken to a remnant low by the end of the forecast period.


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

24 Hr Forecast (0000Z Oct 5)...110 mph maximum sustained wind hurricane centered just west of Bermuda at 32.5N-65.5W

48 Hr Forecast (0000Z Oct 6)...110 mph maximum sustained wind hurricane centered at 35N-62W

72 Hr Forecast (0000Z Oct 7)...85 mph maximum sustained wind hurricane centered at 40N-53W

96 Hr Forecast (0000Z Oct 8)...50 mph maximum sustained wind remnant low northwest of the Azores centered at 42.5N-36W

Track Forecast...Finally a forecast track for Joaquin that is doing good. The hurricane remains on track with my previous forecast track and so I am making no changes tonight.

Intensity Forecast...Due to the expectation of the shear relaxing (but not totally subsiding) as the western Atlantic upper vortex moves away...I currently forecast Joaquin to maintain at least category 2 strength through 48 hours (and my category 2 forecast is raised from 100 to 110 mph due Joaquin currently being above my previous intensity forecast). By 72 to 96 hours I forecast weakening and dissipation due to cooler waters and intense jet stream westerly shear expected at the end of the forecast period (mentioned at the end of both the atmospheric and thermodynamic outlook sections above).

Impact Forecast...Impact swath in the above graphic is an extrapolation of the current 11 PM EDT NHC tropical storm wind field along my forecast track...with shrinkage in the swath for the later part of the forecast where Joaquin is forecast to weaken. On Joaquin's current heading the hurricane will be reaching Bermuda in the next 24 hours and preparations should be rushed to completion if they are not complete already.

...SPECIAL FEATURE...SURFACE LOW INVEST 90-L...
Current Prognosis...Surface low Invest 90-L as of 0000Z earlier this evening was centered at 27N-53W and continues to have a well-defined cloud swirl on satellite pictures. A flare up of showers and thunderstorms has recently developed on the west side of the swirl. Upper-level winds have become more favorable for tropical cyclone formation as the western Atlantic upper vortex that was shearing it has become flung westward and away in a Fujiwhara-like interaction with Hurricane Joaquin. 90-L was earlier moving westward under the influence of the strong 1044 mb eastern Canada surface ridge...but has become stalled due to a 992 mb frontal cyclone and yet another frontal cyclone that will form offshore of Atlantic Canada to the south of the ridge (supported by a northern fracture of an upper trough that has recently left North America). Therefore my updated forecast track is an eastward shift over my previous due to the current stall observed. On a final note...I've noticed 90-L was no longer designated as the remnants of Ida in the NHC tropical weather outlook since Wednesday evening...perhaps because lack of clarity on whether or not the currently well-defined surface circulation is the same circulation that Ida had. So its quiet possible this will not be designated as Ida if 90-L develops into a tropical cyclone.

Atmospheric Outlook for the Forecast Period...90-L has become stalled and is now expected to slowly move north toward a frontal cyclone to form offshore of Atlantic Canada (mentioned in the above current prognosis section). Upper-level winds will become less favorable for development by 48 and 72 hours due to northwesterly vertical shear induced by the upper outflow of Hurricane Joaquin approachign from the west. It is also during this time that the southeast side of Joaquin's low-level circulation will turn 90-L northeastward while absorbing 90-L.

Thermodynamic Outlook for the Forecast Period...This system will be over warm waters (26 to 28 deg C) favorable for tropical development.

24 Hr Forecast (0000Z Oct 5)...35 mph maximum sustained wind tropical depression centered at 28N-53W

48 Hr Forecast (0000Z Oct 6)...35 mph maximum sustained wind tropical depression centered at 32N-53W

72 Hr Forecast (0000Z Oct 7)...Remnant low becoming absorbed by Hurricane Joaquin...centered at 34N-49W

2015 Atlantic Hurricane Season Birdseye Discussion #105

By: NCHurricane2009, 7:28 AM GMT on October 03, 2015

...SATURDAY OCTOBER 3 2015 3:29 AM EDT...
A developing surface frontal gale over the southeastern US coast and western Atlantic upper vortex have begun turning Hurricane Joaquin northeastward away from the Bahamas and on a trajectory toward Bermuda. Hurricane Joaquin is now expected to strike Bermuda at 48 hours...and preparations in Bermuda should begin in earnest and be completed over the next 24 hours. See first special feature section below for more details on Joaquin. Continue to visit www.nhc.noaa.gov for up to the minute latest information on Joaquin.

Surface low Invest 90-L located southeast of Bermuda still has potential to become a tropical cyclone during the next 48 hours. Development after that time is not expected as Hurricane Joaquin will absorb 90-L.

An eastern Atlantic tropical wave located to the southwest of the islands of the Republic of Cabo Verde has become introduced into the National Hurricane Center tropical weather outlook. Conditions will be unfavorable for development over the next 24 hours due to a shear-inducing southward-digging upper trough being delivered by the 1002 mb deep-layered cyclonic gale currently over the Azores. However by 72 and 96 hours this tropical wave could find more favorable upper winds as it moves into the central tropical Atlantic beneath an expanding tropical upper ridge to develop in the wake of the upper trough. Currently not considering this tropical wave as a special feature on this blog until I see how well-organized it is when it gets exposed to the more favorable upper winds.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

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

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...MAJOR HURRICANE JOAQUIN...
Current Prognosis...Joaquin has weakened to a category 3 hurricane over the last 24 hours perhaps due to a slowly-progressing eye wall replacement cycle. The hurricane is moving northeastward away from the Bahamas and toward Bermuda under the influences mentioned in the atmospheric outlook section below...and was centered at 24.5N-74.1W as of 0000Z earlier this evening.

Atmospheric Outlook for the Forecast Period...The upper trough currently over eastern North America (marked by blue-dashed line over eastern Canada in the above atmospheric features chart) has fractured...with Joaquin currently interacting with the southern fracture of the upper trough (marked by blue L over the US Gulf coast and west of Joaquin). Upper divergence on the east side of the southern fracture is currently resulting in the formation of a surface frontal gale over the southeastern US coast...with Joaquin getting kicked northeastward by the southeast side of the gale. The western Atlantic upper vortex interacting with disturbance Invest 90-L (marked by blue L to the northeast of Joaquin) will finish the job of steering Joaquin northeastward toward Bermuda in the next 48 hours. Westerly winds on the south side of this upper vortex will likely induce some shear that weakens Joaquin over the next 24 hours. After that time the upper vortex will shift away from Joaquin while getting flung westward in a fujiwhara-like interaction with Joaquin...which should reduce the shear at 48 and 72 hours. By 96 and 120 hours Joaquin should reach the high-latitude westerly jet stream in the north Atlantic which will surely turn Joaquin eastward while shearing apart the storm.

Thermodynamic Outlook for the Forecast Period...Joaquin is currently over 30 deg C waters very favorable for tropical development...but on the current forecast track should cross the 26 deg C isotherm into cooler waters by 96 hours which will help Joaquin weaken to a remnant low by the end of the forecast period.


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

24 Hr Forecast (0000Z Oct 4)...100 mph maximum sustained wind hurricane centered at 27.5N-69W

48 Hr Forecast (0000Z Oct 5)...100 mph maximum sustained wind hurricane centered just west of Bermuda at 32.5N-65.5W

72 Hr Forecast (0000Z Oct 6)...100 mph maximum sustained wind hurricane centered at 35N-62W

96 Hr Forecast (0000Z Oct 7)...85 mph maximum sustained wind hurricane centered at 40N-53W

120 Hr Forecast (0000Z Oct 8)...50 mph maximum sustained wind remnant low northwest of the Azores centered at 42.5N-36W

Track Forecast...Big story tonight is that Joaquin is turning northeastward away from the Bahamas on a trajectory toward Bermuda...and so the updated forecast track is a significant eastward shift over the previous.

Intensity Forecast...I currently forecast Joaquin to weaken to a category 2 (100 mph max sustained wind hurricane) over the next 24 hours due to westerly shear on the south side of the western Atlantic upper vortex mentioned in the above atmopsheric outlook section. With the shear then weakening (but not totally subsiding) as the upper vortex moves away...I currently forecast Joaquin to maintain category 2 strength through 72 hours. I then forecast weakening and dissipation due to cooler waters and intense jet stream westerly shear expected at the end of the forecast period (mentioned at the end of both the atmospheric and thermodynamic outlook sections above).

Impact Forecast...Impact swath in the above graphic is an extrapolation of the current 11 PM EDT NHC tropical storm wind field along my forecast track. In the short-term...conditions in the central Bahamas will finally improve as Joaquin moves away later today. On Joaquin's current heading the hurricane will be reaching Bermuda by 48 hours and preparations should be underway and completed in the next day. I am no longer mentioning the flood risk in the mid-Atlantic (Carolinas and Virginia) in the above forecast graphic as this flood risk is technically being caused by a seperate surface frontal gale and not Joaquin itself. This flood risk needs to be taken seriously as the vigorous frontal gale is drawing from Joaquin's rich tropical moisture.

...SPECIAL FEATURE...SURFACE LOW INVEST 90-L...
Current Prognosis...Surface low Invest 90-L as of 0000Z earlier this evening was centered at 26.5N-52W and has strengthened (deepened) to 1004 mb as expected due to an upper divergence maximum at the boundary between a western Atlantic upper vortex (marked by blue L to the west of 90-L in the above atmospheric features chart) and upper vortex associated with the deep-layered 1002 mb gale currently over the Azores. 90-L has become less organized due to westerly shear imparted by the western Atlantic upper vortex...and so I have lowered my intensity forecast to only show 90-L becoming a tropical depression. I've noticed 90-L was no longer designated as the remnants of Ida in the NHC tropical weather outlook since Wednesday evening...perhaps because lack of clarity on whether or not the currently well-defined surface circulation is the same circulation that Ida had. So its quiet possible this will not be designated as Ida if 90-L develops into a tropical cyclone.

Atmospheric Outlook for the Forecast Period...Upper-level winds will improve for tropical cyclone formation of 90-L over the next 48 hours as the shearing western Atlantic upper vortex gets flung westward and away in a Fujiwhara-like interaction with Hurricane Joaquin. Yesterday's east-northeast track as expected has reversed to a west-northwest track toward Bermuda while 90-L is now under the steering influence of the strong 1044 mb eastern Canada surface ridge moving offshore. This means 90-L is on a collision course with much more powerful Hurricane Joaquin and will become absorbed by Joaquin by 48 hours (using the latest updated forecast track for Joaquin).

Thermodynamic Outlook for the Forecast Period...This system will be over warm waters (27 to 28 deg C) favorable for tropical development.

24 Hr Forecast (0000Z Oct 4)...35 mph maximum sustained wind tropical depression centered at 28N-55W

48 Hr Forecast (0000Z Oct 5)...35 mph maximum sustained wind tropical depression centered east of Bermuda at 32.5N-60W becoming absorbed by Hurricane Joaquin

2015 Atlantic Hurricane Season Birdseye Discussion #104

By: NCHurricane2009, 12:00 PM GMT on October 02, 2015

**Note: This discussion was completed at 1 AM EDT and was intended for release during that time...but technical difficulties prevented me from releasing it at that time. However...not much has changed with the systems outlined below since then**

...FRIDAY OCTOBER 2 2015 8:00 AM EDT...
Joaquin continues to severely pound the central Bahamas while becoming a category 4 hurricane. Even though computer models have shifted away from showing a mid-Atlantic US landfall (in the Carolinas and Virginia)...a severe rainfall event with flooding potential is still expected in this region. However the eastern US needs to remain on high alert in case the forecast track changes again. See special feature section below for more details on Joaquin. Visit www.nhc.noaa.gov for up to the minute latest information on Joaquin.

A northwestern Atlantic upper trough continues to enhance surface low Invest 90-L (partly associated with the remnants of Ida) located southeast of Bermuda...and 90-L has become better organized. After 24 hours upper winds will become increasingly favorable for tropical cyclone formation as the upper trough weakens. Current expectation is that 90-L will pass north of Bermuda and become absorbed by Joaquin within the next five days...see second special feature section below for additional details.

The deep-layered cyclonic gale over the Azores continues to not show any signs of subtropical cyclone development and will no longer be mentioned on this blog.

...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).

...SPECIAL FEATURE...MAJOR HURRICANE JOAQUIN...
Current Prognosis...Joaquin over the last 24 hours has strengthened further into a category 4 hurricane while moving into the central Bahamas where major impacts are likely occuring at this hour. The hurricane is more symmetrical in structure while sliding into a lower shear/enhanced outflow environment beneath an upper ridge in the western Atlantic (marked by blue-zig-zag line over and north of Joaquin in the above atmopspheric features chart). Recently the small eye (which was located at 22.9N-74.5W as of 0000Z earlier this evening) has disappeared on satellite pictures...but the 11 PM EDT NHC advisory discussion insisted that microwave imagery and aircraft reconaissance observations are not showing an eye wall replacement cycle. However I believe an eye wall replacement cycle is due soon...a scenario which would prevent additional strengthening.

Atmospheric Outlook for the Forecast Period...The upper trough currently over eastern North America (marked by blue-dashed line to the left of Joaquin in the above atmospheric features chart) is about to fracture...with Joaquin to interact with the southern fracture of the upper trough. Northerly winds on the west side of Joaquin is expected to induce southward cool air advection that will cause the southern fracture to amplify into a northwest-southeast tilt...a configuration which will create massive upper air divergence ahead of the southern fracture that could cause Joaquin to transition into a strong non-tropical remnant gale. Support from the upper trough currently moving into California (when the upper trough arrives over the northeastern US or eastern Canada) could also aid in the transition to non-tropical towards the end of the forecast period.

Thermodynamic Outlook for the Forecast Period...Joaquin is currently over 30 deg C waters very favorable for tropical development...but by 48 to 72 hours will be crossing the 26 deg C isotherm into cooler waters which will aid in weakening and/or transition to non-tropical.


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

24 Hr Forecast (0000Z Oct 3)...130 mph maximum sustained wind hurricane centered east of the northwestern Bahamas at 26.5N-74.5W

48 Hr Forecast (0000Z Oct 4)...105 mph maximum sustained wind hurricane centered at 32.5N-74.5W

72 Hr Forecast (0000Z Oct 5)...80 mph maximum sustained wind hurricane centered at 37N-74.5W transitioning to non-tropical

96 Hr Forecast (0000Z Oct 6)...50 mph maximum sustained wind non-tropical remnant low centered over the northeastern US at 42N-74.5W

Track Forecast...Big story tonight is that computer models have shifted away from having Joaquin turning westward into the mid-Atlantic US under the influence of the NW-SE tilted southern fracture upper trough mentioned in the atmospheric outlook section. Instead most of the models now show Joaquin turning northeastward out to sea due to the tug of the upper vortex interacting with disturbance Invest 90-L (marked by blue L to the right of Joaquin in the above atmopsheric features chart). I prefer to wait and see for another 24 hours if the models are consistent with this northeast turn before agreeing...and so for now I am taking a neutral approach while showing Joaquin going straight north while equally tugged by both the NW-SE titled upper trough to the west and upper vortex to the east. I initially show a faster north motion while Joaquin is likely to accelerate under the influence of the NW-SE tilted upper trough...followed by a slower progression to the north due to the 1041 mb strong surface ridge over eastern Canada being present for much of the forecast period and blocking northward progress.

Intensity Forecast...Even though the current report from the NHC insists that no eye wall replacment cycle has begun...I believe the disapperance of the eye from satellite pictures (as noted in the above current prognosis) indicates that Joaquin has a high chance of starting an eye wall replacement cycle soon. Therefore I prefer to show no additional strengthening during the next 24 hours...now bringing me slightly below my previous intensity forecast for the first part of the forecast. After 24 hours...weakening is likely due to northward accleration into relatively cooler waters and due to increased shear during interaction with the NW-SE tilted southern fracture upper trough mentioned in the above atmopsheric outlook section. However the later part of my intensity forecast is raised due to the fact Joaquin spends time over water instead of making landfall in the mid-Atlantic US as previously forecasted.

Impact Forecast...In the short-term...the central Bahamas will continue to deal with a severe strike for the islands that get exposed to the intense core of the hurricane. The tropical storm wind field has expanded in size such that the northeast coast of Cuba has received some tropical storm winds and is now under a tropical storm warning. Another big story tonight is the severe rainfall and flooding event forecast for the mid-Atlantic US (Carolinas and Virginia) even though Joaquin is no longer forecast to move into the mid-Atlantic. One factor that is enhancing the flood risk in this region is that the ground is already saturated from the rains associated with previous tropical disturbances Invest 97-L and 99-L. Another factor is that Joaquin's rich moisture will get drawn into the widespread and strong upper divergence to develop on the east side of the NW-SE tilted southern fracture upper trough mentioned in the above atmsopheric outlook section. The low-level convergence of the strong surface cold front tied to this upper trough coupled with the aforementioned widespread and strong upper divergence will trigger very heavy rains with the moisture drawn in from Joaquin. States of Emergencies and flood advisories are in effect for the Carolinas and Virginia in anticipation of this flood event.

...SPECIAL FEATURE...SURFACE LOW INVEST 90-L...
Current Prognosis...As of 0000Z surface low Invest 90-L was located at 26N-54W while accelerating east-northeastward under the influence of a northwest Atlantic upper trough/vortex (marked by blue L immediately northwest of Invest 90-L in the above atmospheric features chart) and under the tug of the deep-layered 1001 mb gale over the Azores. This east-northeast acceleration has allowed 90-L to somewhat catch up to the upper southwesterly wind speed ahead of the upper trough/vortex...hence reducing the effect of southwesterly shear and allowing 90-L to become better organized with thunderstorms bands. However the shear is not entirely eliminated as recent satellite pictures just after 0000Z showed the thunderstorms becoming biased again to the east of the center. Given the improved organization I have moved up the time of forecast tropical storm formation from 0000Z Oct 5 to 0000Z Oct 4. Despite my slightly higher initial intensity though I have lowered the later part of my intensity forecast due to westerly shear and potential early absorption of this system into Joaquin mentioned in the atmopsheric outlook section below. Also with the east-northeast acceleration...I have adjusted the early part of my forecast eastward...but then the later part of my forecast is as far west as my previous due to strong steering currents expected to develop between Joaquin and a surface ridge as mentioned in the atmospheric outlook section below. On a final note...I've noticed 90-L was no longer designated as the remnants of Ida in the NHC tropical weather outlook since Wednesday evening...perhaps because lack of clarity on whether or not the currently well-defined surface circulation is the same circulation that Ida had. So its quiet possible this will not be designated as Ida if 90-L develops into a tropical cyclone.

Atmospheric Outlook for the Forecast Period...Over the next 24 hours expecting Invest 90-L to strengthen in an upper divergence maximum to develop at the boundary between the northwest Atlantic upper trough and northeast Atlantic upper vortex associated with the deep-layered 1001 mb gale currently over the Azores. After 24 hours the western Atlantic upper trough is currently forecast to weaken...but 90-L will remain under westerly shear while embedded in upper westerlies on the north side of the western Atlantic upper ridge (marked by blue-zig-zag line to the left of 90-L in the above atmospheric features chart) and out ahead of the upper trough that will be associated with non-tropical Joaquin. In particular if my forecast track for 90-L below verifies...90-L will arrive into a hostile westerly jet after 96 hours that should induce weakening from peak intensity. Currenlty expecting the east-northeast track to reverse to a west-northwest to northwest track as the strong surface 1041 mb ridge over eastern Canada will have moved offshore and acclerate 90-L toward Joaquin. I currently assume that 90-L will become absorbed by Joaquin at 120 hours using my straight north track for Joaquin. However if current computer model trends continue...I will be shifting my track for Joaquin to the northeast which means 90-L will become absorbed much sooner (by 72 hours).

Thermodynamic Outlook for the Forecast Period...This system will be over warm enough waters favorable for tropical development until 96 hours...when it will cross the the 26 deg C isotherm into cooler waters which will also aid in the forecast weakening at 120 hours as shown below.

24 Hr Forecast (0000Z Oct 3)...Strengthening surface low centered at 26.5N-52W

48 Hr Forecast (0000Z Oct 4)...40 mph maximum sustained wind tropical storm centered at 28N-55W

72 Hr Forecast (0000Z Oct 5)...45 mph maximum sustained wind tropical storm centered east of Bermuda at 32.5N-60W

96 Hr Forecast (0000Z Oct 6)...45 mph maximum sustained wind tropical storm centered midway between Bermuda and Massachusetts at 37.5N-65.5W

120 Hr Forecast (0000Z Oct 7)...Remnant low offshore of the northeastern US becoming absorbed by non-tropical Joaquin...centered at 40N-66W

2015 Atlantic Hurricane Season Birdseye Discussion #103

By: NCHurricane2009, 5:27 AM GMT on October 01, 2015

...THURSDAY OCTOBER 1 2015 1:27 AM EDT...
Alert! Joaquin strengthens rapidly into a category 3 hurricane...and is likely to produce severe and perhaps historic impacts to the central and western Bahamas over the next 48 hours while forecast to strengthen into a category 4 or possibly 5 hurricane. All preparations in the Bahamas should be completed by now...or rushed to completion immediately. The mid-Atlantic United States is likely to also receive a severe strike from Joaquin this weekend and it is recommended that residents in this region should begin thinking about preparations. See first special feature section below for more information on Joaquin. Continue to visit www.nhc.noaa.gov for up-to-the-minute latest information on this dangerous hurricane.

A northwestern Atlantic upper trough continues to enhance the remants of Ida located southeast of Bermuda. After 48 hours upper winds will become increasingly favorable for the re-genesis of Ida as the upper trough dissipates. See second special feature section below for additional details on this situation. Interests in Bermuda should monitor this situation as Ida has the potential to move northwestward toward the island.

A deep-layered cyclonic gale persists in the northeastern Atlantic in the vicinity of the Azores. Even though sea-surface tempeatures in the Azores are only in the 21 deg C range...instability provided by cold temps of the upper layers of the deep-layered gale could cause the gale to evolve into a subtropical cyclone. Currently there are no signs of this occuring. After 48 hours...the upper trough associated with the 1008 mb southern Greenland frontal cyclone will amplify into a major upper vortex that will pull the gale northwestward from the Azores...with potential for rough weather to continue as the gale remains strong with the support of the major upper vortex.

...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...MAJOR HURRICANE JOAQUIN...
Current Prognosis...Joaquin has continued to do extremely well under light northerly shear...developing a small eye in its organized thunderstorm structure and rapidly intensifying into the second major hurricane (category 3 or greater) of the 2015 Atlantic season. As of 0000Z earlier this evening the dangerous eye of Hurricane Joaquin was located at 24N-73W and was continuing on a southwest drift into the central Bahamas. As such...the central and western Bahamas are likely to be dealt a severe blow during the next 48 hours and all preparations should have been completed or should be rushed to completion by now.

Atmospheric Outlook for the Forecast Period...Joaquin has been moving southwestward en route to the central Bahamas perhaps for two reasons. One is that the surface center has continued to regenerate southward into its well organized and strong thunderstorm structure that has been releasing a lot of latent heat...creating surface pressure drops through tropical processes that are continuing to pull the center southward. The second reason is that a weak surface ridge has developed over Cuba and the western Caribbean (currently marked at 1011 mb in the above atmopsheric features chart)...supported by eastern convergence of the upper ridge axis expanding into the western Atlantic (marked by blue-zig-zag line to the left of Joaquin). As such I forecast Joaquin to continue southwest into 23N latitude over the next 24 hours. After that time...the upper trough currently over eastern North America (marked by blue-dashed line) will fracture...with Joaquin interacting with the southern fracture of the upper trough by 72 hours and beyond. Northerly winds on the west side of Joaquin is expected to induce southward cool air advection that will cause the southern fracture to amplify into a northwest-southeast tilt...a configuration which will create massive upper air divergence ahead of the southern fracture that will cause Joaquin to transition into a strong non-tropical remnant gale while moving into the mid-Atlantic US. This tilt will also cause the upper trough to pull Joaquin westward into the mid-Atlantic US. By the end of the forecast period...the upper trough currently offshore of California will be moving through central US and Ohio Valley...causing Joaquin to turn northeast into the New England states as a non-tropical remnant low supported by divergence on the east side of the upper trough.

Thermodynamic Outlook for the Forecast Period...Joaquin is currently over 30 deg C waters very favorable for tropical development which helps explain the current period of rapid strengthening...and the potential for Joaquin to strengthen further into a category 4 (or perhaps a category 5) hurricane.


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

24 Hr Forecast (0000Z Oct 2)...145 mph maximum sustained wind hurricane centered over the central Bahamas at 23N-76W

48 Hr Forecast (0000Z Oct 3)...140 mph maximum sustained wind hurricane centered very near the western Bahamas at 26.5N-76W

72 Hr Forecast (0000Z Oct 4)...120 mph maximum sustained wind hurricane centered offshore of the Carolinas at 32.5N-76.5W

96 Hr Forecast (0000Z Oct 5)...75 mph maximum sustained wind hurricane centered over the Carolinas at 35.5N-80W transitioning to non-tropical

120 Hr Forecast (0000Z Oct 6)...35 mph maximum sustained wind non-tropical remnant low centered over the Maryland/Pennsylvania Border at 40N-78W

Track Forecast...Once again forced to do a southward adjustment to all forecast points due to the observations noted in the first part of the above atmospheric outlook section. With Joaquin also stronger than previously forecast...the cool air advection on his west side will also be more signficant which will cause more amplification of the southern fracture upper trough he will be interacting with...to the degree that the upper trough amplifies into an upper vortex that whirls Joaquin westward right into the mid-Atlantic US and so all my later forecast points are adjusted westward.

Intensity Forecast...Yet again...Joaquin is stronger than my previous intensity forecast. In the next 48 hours as Joaquin slides directly under the western Atlantic upper ridge axis...he will be in a very favorable environment of lower shear and enhanced upper outflow. Coupled with warm waters in the 30 deg C range...the NHC and I both show intensification to a category 4...but there is a chance that Joaquin goes all the way to category 5. After 48 hours...weakening is expected due to increasing shear as Joaquin interacts with the southern fracture of an upper trough...but this interaction (detailed in the above atmospheric outlook section) will cause Joaquin to only slowly weaken as he moves inland into the mid-Atlantic US.

Impact Forecast...In the short-term...the western and central Bahamas are about to deal with a severe and potentially historic impact from Joaquin due to his potential to become a category 4 or 5 hurricane in the next couple of days. All preparations should have been completed or should be rushed to completion by now. Even though I show weakening at 72 hours...I expand the size of the impact swath in the above graphic (based on the size of the 11 PM EDT tropical storm wind field) as Joaquin's wind field could grow due to a large area of surface pressure falls associated with widespread upper divergence ahead of the southern fracture of the upper trough. If a large wind field such as this materializes...a significant and potentially historic storm surge event would occur on the mid-Atlantic US coast to the north of the storm center during landfall.

...SPECIAL FEATURE...REMNANTS OF IDA (INVEST 90-L)...
Current Prognosis...The remnant surface low of former Tropical Storm Ida is located at 25N-57.5W and has become a little better organized over the last 24 hours and as a result I have moved up the forecast time of tropical cyclone formation from 0000Z Oct 5 to 0000Z Oct 4. The remnant is currently tied to and enhanced by an upper divergence maximum ahead of a northwest Atlantic upper trough/vortex that has been diving southward (marked by blue-dashed line to the north of Invest 90-L in the above atmospheric features chart).

Atmospheric Outlook for the Forecast Period...Over the next 48 hours expecting the remnant low of Ida to remain stationary at 25N-57.5W while strengthening in an upper divergence maximum to develop at the boundary between the northwest Atlantic upper trough and northeast Atlantic upper vortex associated with the deep-layered 1003 mb gale currently over the Azores. After 48 hours the western Atlantic upper trough is currently forecast to weaken into a northwest-southeast tilted upper trough with its upper divergence maximum shifting northward and hence causing Ida to drift northward with the maximum. After 72 hours the dissipating upper trough will be weak enough to no longer influence the track of Ida...but perhaps still be applying some light westerly shear (which is why I only currently forecast slow strengthening in the later part of the forecast period). By 72 to 120 hours...current expectation is that Joaquin will have evolved into a massive circulation in the western Atlantic/eastern US with the 1033 mb surface ridge currently over eastern Canada moving into the north-central Atlantic. Therefore I currently forecast some northwestward motion toward Bermuda in the southeasterly flow between Joaquin and the ridge during that time.

Thermodynamic Outlook for the Forecast Period...This system will be over 27 to 30 deg C waters that will be supportive of tropical cyclone formation.

24 Hr Forecast (0000Z Oct 2)...Remnant low centered at 25N-57.5W

48 Hr Forecast (0000Z Oct 3)...Strengthening remnant low centered at 25N-57.5W

72 Hr Forecast (0000Z Oct 4)...35 mph maximum sustained wind tropical depression centered at 27.5N-57.5W

96 Hr Forecast (0000Z Oct 5)...40 mph maximum sustained wind tropical storm centered at 30N-60W

120 Hr Forecast (0000Z Oct 6)...50 mph maximum sustained wind tropical storm centered just southeast of Bermuda at 32.5N-62.5W


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

NCHurricane2009 doesn't have a bio yet.