NCHurricane2009's Blog

2015 Atlantic Hurricane Season Birdseye Discussion #50

By: NCHurricane2009, 4:06 AM GMT on July 31, 2015

...FRIDAY JULY 31 2015 12:06 AM EDT...
The 1012 mb surface low offshore of the southeastern US continues northeast in advance of the 985 mb frontal cyclone over the eastern US and eastern Canada. Development into a tropical cyclone is not likely due to the broad nature of the circulation and unfavorable northerly vertical shear induced by the east side of the upper ridge over the southern US (marked by blue H in the atmospheric features chart below). In the next 24 hours...the 1012 mb low will become absorbed offshore by the cold front of the aforementioned 985 mb frontal cyclone.

Tropical surface low Invest 94-L currently located southwest of the Cape Verde Islands in the eastern tropical Atlantic continues westward. Even though Invest 94-L is under a favorable low shear and good upper outflow environment under an upper ridge (marked by blue H in the lower-right corner of the atmospheric features chart)...none of the computer models forecast significant development of 94-L...perhaps due to the expansive amount of dry Saharan air in the envrionment ahead of the tropical wave as seen in the bottom-center of the thermodynamics chart below. The amount of heavy thunderstorms in the circulation of 94-L is less relative to 24 hours ago...perhaps a sign that 94-L is beginning to struggle with the dry air.

...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).

2015 Atlantic Hurricane Season Birdseye Discussion #49

By: NCHurricane2009, 12:47 AM GMT on July 30, 2015

...WEDNESDAY JULY 29 2015 8:47 PM EDT...
A surface frontal zone remains draped across the western Atlantic. At the tail end of the frontal zone remains a more tropical 1012 mb surface low that has recently moved northeastward from the Florida Peninsula into the waters offshore of the southeastern US in advance of the 990 mb frontal cyclone moving through the central US and central Canada. Because the 1012 mb center is now offshore and over warm water the National Hurricane Center has introduced it into their tropical weather outlook this evening. Development into a tropical cyclone is not likely due to the broad nature of the circulation and unfavorable northerly vertical shear induced by the east side of the upper ridge over the southern US (marked by blue H in the atmospheric features chart below). By 48 hours...the 1012 mb low will become absorbed offshore by the cold front of the aforementioned 990 mb frontal cyclone. In the meantime...the west side of the 1012 mb low will continue to spread locally heavy rain across Florida and the southeastern US as it continues northeast.

As marked in the lower-right corner of the atmospheric features chart below...the tropical wave that has recently rolled off the west coast of Africa has left behind its organized 1010 mb tropical low pressure spin that has gained concentration in its thunderstorm activity. As a result this tropical low pressure spin has become upgraded to disturbance Invest 94-L on the Naval Research Laboratory site of the US Navy and has become introduced in the National Hurricane Center tropical weather outlook. Even though Invest 94-L is under a favorable low shear and good upper outflow environment under an upper ridge (marked by blue H in the lower-right corner of the atmospheric features chart)...none of the computer models forecast significant development of 94-L...perhaps due to the expansive amount of dry Saharan air in the envrionment ahead of the tropical wave as seen in the bottom-center of the thermodynamics chart below. If 94-L were to quickly organize further prior to reaching this dry air...I will be upgrading it to 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 1200Z and 1330Z-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 #48

By: NCHurricane2009, 3:37 AM GMT on July 29, 2015

...TUESDAY JULY 28 2015 11:37 PM EDT...
A surface frontal zone remains draped across the western Atlantic. At the tail end of the frontal zone remains a more tropical 1012 mb surface low located over the Florida Peninsula. This disturbance is expected to slowly move northward into the southeastern US over the next few days...and because it has a broad elongated structure it is unlikely this system will consolidate into a tropical cyclone before moving into the southeastern US.

As marked in the lower-right corner of the atmospheric features chart below...a tropical wave appears to be rolling off the west coast of Africa into the eastern tropical Atlantic. The tropical wave has some signs of organization with the apperance of spiral thunderstorm bands...and the tropical wave is under a favorable low shear and good upper outflow environment under an upper ridge (marked by blue H in the lower-right corner of the atmospheric features chart). Despite this...none of the computer models forecast this tropical wave to develop...perhaps due to the expansive amount of dry Saharan air in the envrionment ahead of the tropical wave as seen in the bottom-center of the thermodynamics chart below.

...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 #47

By: NCHurricane2009, 1:33 AM GMT on July 28, 2015

...MONDAY JULY 27 2015 9:34 PM EDT...
A surface frontal zone remains draped across the western Atlantic. At the tail end of the frontal zone remains a more tropical 1014 mb surface low located over the Florida Peninsula and northern Gulf of Mexico. This disturbance is expected to slowly move northward into the southeastern US over the next few days...and because it has a broad elongated structure it is unlikely this system will consolidate into a tropical cyclone before landfall.

...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 #46

By: NCHurricane2009, 3:11 AM GMT on July 27, 2015

...SUNDAY JULY 26 2015 11:11 PM EDT...
A surface frontal zone remains draped across the western Atlantic. The tail end of the frontal zone has decayed into a more tropical 1011 mb surface low located over the Florida Peninsula and northern Gulf of Mexico. This disturbance is expected to slowly move northward into the southeastern US over the next few days...and because it has a broad elongated structure it is unlikely this system will consolidate into a tropical cyclone before landfall.

A vigorous tropical wave is currently located west-southwest of the Cape Verde Islands...and another vigorous tropical wave has just rolled off the west coast of Africa into the eastern tropical Atlantic as marked in the lower-right corner of the atmospheric features chart below. However none of the computer models forecast these tropical waves to develop and thermodynamic conditions are unfavorable with an abundance of dry Saharan air across the eastern part of the Atlantic basin as seen in the lower-right corner of the thermodynamics chart below.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1920Z-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 #45

By: NCHurricane2009, 4:24 AM GMT on July 26, 2015

...SUNDAY JULY 26 2015 12:25 AM EDT...
A surface frontal zone remains draped across the western Atlantic. A disturbance along the front located over the Florida peninsula and eastern Gulf of Mexico has developed under the support of split flow upper divergence between a shortwave upper trough entering the Atlantic from the southeastern US and an upper ridge over the southern US. The National Hurricane Center continues to mention this disturbance in their 5 day tropical weather outlook. The latest computer model runs suggest this disturbance will slowly move northward into the southeastern US over the next few days and therefore is not likely to develop due to land interaction.

A vigorous tropical wave with a 1012 mb low pressure center is presently in the eastern tropical Atlantic passing south of the Cape Verde Islands as marked in the lower-right corner of the atmospheric features chart below. However none of the computer models forecast it to develop and thermodynamic conditions are unfavorable with an abundance of dry Saharan air across the eastern part of the Atlantic basin as seen in the lower-right corner of the thermodynamics chart below.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1924Z-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 #44

By: NCHurricane2009, 2:11 AM GMT on July 25, 2015

...FRIDAY JULY 24 2015 10:12 PM EDT...
A surface frontal zone remains draped across the western Atlantic. A 1011 mb frontal depression just offshore of the southeastern US has formed along the front while supported by divergence on the east side of an upper shortwave trough diving southeast across the eastern US. This frontal depression is expected to move northeast across the Atlantic and remain non-tropical in nature. In the wake of this frontal depression the surface frontal boundary is expected to linger offshore of the southeastern US...but potential for tropical development along the front will initially be capped by a cut-off upper vortex to be left behind by the aforementioned shortwave and another upper trough moving offshore from the US. However by 5 to 6 days computer models suggest upper winds could become more favorable for tropical development along the front. The National Hurricane Center has introduced this front in their 5 day tropical weather outlook...and interests in the western Atlantic and the east coast of the US should monitor the progress of this front over the next few days.

Satellite imagery suggests a strong tropical wave has emerged from western Africa as marked in the lower-right corner of the atmospheric features chart below. However none of the computer models forecast it to develop and thermodynamic conditions are unfavorable with an abundance of dry Saharan air across the eastern part of the Atlantic basin as seen in the lower-right corner of the thermodynamics chart below.

...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 #43

By: NCHurricane2009, 1:00 AM GMT on July 24, 2015

...THURSDAY JULY 23 2015 9:00 PM EDT...
The 985 mb frontal cyclone and associated upper vortex marked over the northeastern US and eastern Canada in the atmospheric features chart below has driven a surface front into the western Atlantic. Within the next 24 hours...an upper shortwave diving on the back side of the aforementioned upper vortex will trigger the formation of a non-tropical surface low along the frontal boundary located just offshore of the southeastern US that will subsequently move northeast across the Atlantic. In the wake of this non-tropical surface low the surface frontal boundary is expected to linger offshore...but potential for tropical development along the front will initially be capped by a cut-off upper vortex to be left behind by the aforementioned shortwave and another upper trough moving offshore from the US. However by 6 to 7 days upper winds could finally become more favorable for tropical development along the front.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1924Z-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 #42

By: NCHurricane2009, 12:30 AM GMT on July 23, 2015

...WEDNESDAY JULY 22 2015 8:30 PM EDT...
The 1000 mb frontal cyclone and associated upper vortex marked over the northeastern US and eastern Canada in the atmospheric features chart below is driving a surface front into the western Atlantic. A flare up of showers and thunderstorms has developed along the front just west of Bermuda under favorable low shear and enhanced outflow of an upper ridge located just south of the front (marked by blue H and blue zig-zag line in the atmospheric features chart below). There are currently no signs of tropical development in this thunderstorm flare up...and this area only has 48 hours to develop before an upper shortwave diving on the back side of the aforementioned upper vortex increases unfavorable wind shear over this area. The upper shortwave will trigger the formation of a non-tropical surface low along the frontal boundary that will subsequently move northeast across the Atlantic. In the wake of this non-tropical surface low the surface frontal boundary could linger offshore...but potential for tropical development along the front by that time could be capped by a cut-off upper vortex to be left behind by the aforementioned shortwave and another upper trough moving offshore from the US.

...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 #41

By: NCHurricane2009, 2:29 AM GMT on July 22, 2015

...TUESDAY JULY 21 2015 10:30 PM EDT...
The 993 mb frontal cyclone and associated upper vortex marked over the northeastern US and eastern Canada in the atmospheric features chart below will drive a surface frontal boundary into the Atlantic within the next five days. During this time divergence on the east side of an upper shortwave diving on the back side of the upper vortex will trigger the formation of a non-tropical surface low along the frontal boundary at a location just offshore of the southeastern US that will subsequently move northeast across the Atlantic. In the wake of this non-tropical surface low the surface frontal boundary could linger offshore...but potential for tropical development along the front by that time could be capped by a cut-off upper vortex to be left behind by the aforementioned shortwave and another upper trough moving offshore from the US.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

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

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 #40

By: NCHurricane2009, 1:34 AM GMT on July 21, 2015

...MONDAY JULY 20 2015 9:34 PM EDT...
The 989 to 1003 mb frontal system and associated longwave upper trough marked over the northeastern US and eastern Canada in the atmospheric features chart below will drive a surface frontal boundary into the Atlantic within the next five days. During this time divergence on the east side of an upper shortwave diving on the back side of the upper longwave will trigger the formation of a surface low along the frontal boundary at a location just offshore of the southeastern US that will subsequently move northeast across the Atlantic. With this surface low expected to be supported by the forecast upper shortwave through its lifetime...not expecting this surface low to be tropical in nature.

...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).

2015 Atlantic Hurricane Season Birdseye Discussion #39

By: NCHurricane2009, 10:59 PM GMT on July 19, 2015

...SUNDAY JULY 19 2015 6:59 PM EDT...
A cluster of shower and thunderstorms offshore of the southeastern United States and southwest of Bermuda...in addition to a 1014 mb surface low and surface trough over the northeastern Gulf of Mexico and southeastern US... continues to be supported by upper divergence on the southeastern quadrant of a southern US upper ridge (marked by blue H in the atmospheric features chart below). There continues to be no signs of tropical development in this activity. Elsewhere...the 990 mb frontal cyclone moving into eastern Canada and northeastern US will slowly drive a surface frontal boundary into the Atlantic over the next few days that will also be watched.

The strongest tropical wave of the season thus far is rolling off of the west coast of Africa as marked in the lower-right corner of the atmopsheric featuers chart below. Although this tropical wave is moving into a favorable low shear and enhanced outflow of an upper ridge (marked by blue zig-zag line in the lower-right corner of the atmospheric features chart below)...an unfavorable upper vortex to the northwest of the tropical wave (marked by blue L and blue dashed line) is breaking through the upper ridge and therefore development of this tropical wave is not expected.

...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).

2015 Atlantic Hurricane Season Birdseye Discussion #38

By: NCHurricane2009, 7:35 PM GMT on July 18, 2015

...SATURDAY JULY 18 2015 3:35 PM EDT...
Tropical low Invest 93-L midway between the Lesser Antilles and Cape Verde Islands has become disorganized and has lost shower and thunderstorm activity. Therefore it is no longer expected to develop.

Shower and thunderstorm activity along a surface frontal boundary offshore of the southeastern United States continues to be supported by upper divergence on the southeastern quadrant of a southern US upper ridge (marked by blue H in the atmospheric features chart below). This activity has expanded into the northeastern Gulf of Mexico over the last 36 hours. There are no signs of tropical development in this activity. Elsewhere...the broad 1001 to 1004 mb frontal system currently over the north-central US and south-central Canada will slowly drive another surface frontal boundary into the Atlantic over the next few days that will also be watched.

A tropical wave just southwest of the Cape Verde Islands has produced a concentrated cluster of thunderstorms while taking advantage of low shear and enhanced outflow of an upper ridge (marked by blue zig-zag line in the lower-right corner of the atmospheric features chart below). However an unfavorable upper vortex to the northwest of the tropical wave (marked by blue L) is expected to break through the upper ridge and therefore development of this tropical wave is not expected.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0600Z and 0727Z-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 #37

By: NCHurricane2009, 4:49 AM GMT on July 17, 2015

...FRIDAY JULY 17 2015 12:50 AM EDT...
The tropical wave southwest of the Cape Verde Islands is currently midway between the Lesser Antilles and Cape Verde Islands and has continued to organize into a tropical low with an expansive area of thunderstomrs. As such it has been introduced into the National Hurricane Center tropical weather outlook and has been upgraded to Invest 93-L on the Naval Research Laboratory site of the US Navy. The Lesser Antilles should monitor this system as it has potential to reach the islands as a tropical cyclone not long after 72 hours (3 days). See special feature section below for additional details on this developing situation.

A small but strong area of thunderstorms has flared up along a surface frontal boundary just offshore of the southeastern United States...supported by split flow upper divergence between the south side of its associated upper trough (marked by blue-dashed line just offshore of the eastern US in the atmospheric features chart below) and east side of an upper ridge over the southern US (marked by blue H). Considering the recent development of Claudette earlier this week in this general region...watching to see if a tropical disturbance will develop here. Unless something were to organize quickly in the next 24 hours...signficant development does not appear likely as such a disturbance could struggle with light northerly shear induced by the east side of the aforementioned upper ridge and considering it will likely be accelerated northeastward out to sea by the 1005 mb frontal cyclone currently moving across the north-central US by 72 hours.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

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

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...INVEST 93-L...
Current Prognosis...Latest analysis from the National Hurricane Center TAFB suggests that the tropical wave currently midway between the Lesser Antilles has left behind a 1012 mb tropical surface low. Therefore it is likely the tropical wave will continue westward and away while the 1012 mb tropical low will become the area of focus. As of 0000Z satellite imagery suggests the 1012 mb tropical low has become well organized with spiral banding features near the center maturing and upper outflow present in all quadrants while centered at 10.5N-37W. Satellite animation suggests the organizing tropical low is moving westward at a rate of 1 degree longitude per 3 hours (or 8 degrees longitude per 24 hours).

Atmospheric Outlook for the Forecast Period...Thru the forecast period Invest 93-L is expected to be steered west-northwestward by the southwest quadrant of what is now the 1024 to 1023 mb Atlantic subtropical ridge marked in the above atmospheric features chart. The forecast track below is initially based on the 8W per 24 hour pace observed in the above current prognosis section...but is later slowed as to not get too far ahead of the model guidance and as the system moves toward the weaker western side of the steering subtropical ridge. Upper-level winds continue to be favorable for 93-L under the low shear and enhanced outflow of an upper ridge (marked by blue zig-zag line and blue H in the lower-right corner of the atmospheric features chart above). Upper-level winds early in the forecast are expected to remain favorable for development as 93-L continues west as the upper vortex currently over the Lesser Antilles (marked by blue L) is expected to weaken into an upper trough while the aforementioned upper ridge expands westward in its wake. By the end of the forecast period 93-L will move into westerly shear on the southeast side of the aforementioned upper trough. Therefore if the forecast below verifies...93-L likely will not survive much beyond the forecast period due to westerly shear and land interaction with Hispaniola (Haiti and the Dominican Repbulic).

Thermodynamic Outlook for the Forecast Period...The forecast track will take this system across favorable 27 to 28 deg C waters. Dry air is unlikely to be a problem as the above thermodynamic chart shows that the expansive thunderstorms of 93-L has moistened the immediate atmosphere and as upper divergence on the east side of the upper vortex currently over the Lesser Antilles has moistened the environment ahead of 93-L.

24 Hr Forecast (0000Z Jul 18)...Tropical low centered at 11N-45W

48 Hr Forecast (0000Z Jul 19)...40 mph max sustained wind tropical storm centered at 12N-52W

72 Hr Forecast (0000Z Jul 20)...50 mph max sustained wind tropical storm centered just east of the Lesser Antilles at 13.5N-58W

96 Hr Forecast (0000Z Jul 21)...60 mph max sustained wind tropical storm in the eastern Caribbean Sea centered at 15N-64W. Tropical storm under light westerly shear.

120 Hr Forecast (0000Z Jul 22)...45 mph max sustained wind tropical storm centered just southwest of Puerto Rico and moving west-northwest toward the Dominican Republic...centered at 17N-69W. Tropical storm weakening rapidly due to increased westerly shear.

2015 Atlantic Hurricane Season Birdseye Discussion #36

By: NCHurricane2009, 11:55 AM GMT on July 16, 2015

...THURSDAY JULY 16 2015 7:55 AM EDT...
Recent satellite imagery suggests the tropical wave located well to the southwest of the Cape Verde Islands is producing a concentrated area of thunderstorms. Upper-level winds continue to be favorable for the tropical wave under the low shear and enhanced outflow of an upper ridge (marked by blue zig-zag line in the lower-right corner of the atmospheric features chart below). Upper-level winds are forecast to remain favorable for development as the tropical wave continues west as the upper vortex currently over the Lesser Antilles (marked by blue L) is expected to weaken while the aforementioned upper ridge expands westward in its wake. Currently the only computer model that suggests development from this wave is the usually over-aggressive CMC computer model. Will continue to watch this tropical wave.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0600Z and 0720Z-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 temperature isotherms at http://www.nhc.noaa.gov/satellite.php...the site from which the above thermo chart is generated from...are currently outdated. Therfore I have approximated the 26 deg C isotherm in the above chart using the sea-surface temperature maps available at www.wunderground.com/hurricane. 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 #35

By: NCHurricane2009, 5:28 AM GMT on July 15, 2015

...WEDNESDAY JULY 15 2015 1:28 AM EDT...
Claudette has transitioned into a weakening non-tropical remnant low as expected while moving northeastward toward Newfoundland. Impacts to Newfoundland are not expected to be significant.

Disturbed weather across the Central Caribbean Sea has become less organized as upper winds become less favorable for tropical development. Upper-level wind forecasts are also less favorable than previous forecasts and therefore no development is expected here.

Recent satellite imagery suggests a tropical wave southwest of the Cape Verde Islands is becoming better organized near 10N-30W. Upper-level winds are currently favorable for the tropical wave under the low shear and enhanced outflow of an upper ridge (marked by blue zig-zag line in the lower-right corner of the atmospheric features chart below). Upper-level winds are forecast to remain favorable for development as the tropical wave continues west as the upper vortex currently east of the Lesser Antilles (marked by blue L) is expected to weaken while the aforementioned upper ridge expands westward in its wake. Therefore even though current computer model runs do not forecast this troical wave to develop...will watch this tropical wave.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

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

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

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

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

...THERMODYNAMICS BIRDSEYE CHART...

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

Sea-surface temperature isotherms at http://www.nhc.noaa.gov/satellite.php...the site from which the above thermo chart is generated from...are currently outdated. Therfore I have approximated the 26 deg C isotherm in the above chart using the sea-surface temperature maps available at www.wunderground.com/hurricane. 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 #34

By: NCHurricane2009, 4:53 AM GMT on July 14, 2015

...TUESDAY JULY 14 2015 12:55 AM EDT...
Invest 92-L has become Tropical Storm Claudette...the third tropical storm of the 2015 Atlantic Hurricane Season. The storm is expected to move northeastward into Newfoundland by 36 hours as a weakening remnant non-tropical low. See special feature section below for additional detials on Claudette. Visit www.nhc.noaa.gov for up to the minute latest information on Claudette.

An upper vortex centered just north of the Bahamas (marked by blue L in the atmospheric features chart below) continues to enhance the poleward upper outflow over the surface ITCZ (intertropical convergence zone) in the southern Caribbean Sea...resulting in active weather across the southern and central Caribbean Sea. Upper-level wind forecasts indicate that a favorable upper anticyclone will gradually amplify over this area of disturbed weather...with the upper anticyclone forecast to shift westward across the western Caribbean...Central America...the Bay of Campeche...and southeastern Mexico over the next five days. Computer models currently do not forecast development from this system...however will watch this area for development over the next 5 days.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

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

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

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

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

...THERMODYNAMICS BIRDSEYE CHART...

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

Sea-surface temperature isotherms at http://www.nhc.noaa.gov/satellite.php...the site from which the above thermo chart is generated from...are currently outdated. Therfore I have approximated the 26 deg C isotherm in the above chart using the sea-surface temperature maps available at www.wunderground.com/hurricane. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...TROPICAL STORM CLAUDETTE...
Current Prognosis...As of the 11 PM EDT National Hurricane Center advisory Claudette was centered at 38.9N-64.9W moving rapidly northeastward across the northwestern Atlantic on a course toward Newfoundland. The most recent satellite frames suggest southwesterly vertical shear over the storm is increasing as the swirl center is becoming exposed while the associated thunderstorms become more lopsided to the northeast of the center.

Atmospheric Outlook for the Forecast Period...While steered by the 1002 mb frontal depression over the Ohio Valley and 1000 to 1002 mb southeast Canada/Great Lakes frontal cyclone following behind...Claudette will accelerate northeastward into Newfoundland by 36 hours. The shortwave upper trough associated with the Ohio Valley system has begun to move offshore and near Claudette...which has caused an increase in southwesterly vertical shear as noted in the above current prognosis. As Claudette approaches Newfoundland...Claudette is expected to transition into a non-tropical remnant gale supported by upper divergence on the east side of the shortwave.

Thermodynamic Outlook for the Forecast Period...Claudette has just crossed the 26 deg C isotherm into cooler waters...which will help transition this system from tropical to non-tropical as it moves toward Newfoundland.



Track Forecast...The 11 PM EDT NHC advisory notes that Claudette continues to track to the right of previous forecasts...and the 11 PM EDT center fix suggests Claudette is 2 longitude east of where I predicted it would be during special update #33A. My forecast track in the above graphic is a 2 longitude east shift of the track shown in special update #33A.

Intensity Forecast...Intensity forecast in the above graphic is the same as shown in special update #33A which shows a slow weakening despite the increasing shear and cooler waters as Claudette will tap into some supportive upper divergence on the east side of a shortwave upper trough as mentioned at the end of the above atmospheric outlook section.

Impact Forecast...Impact swath in the above forecast graphic is an extrapolation of the 11 PM EDT NHC advisory tropical storm wind field along the forecast track. The swath is not extended into Newfoundland as Claudette is expected to be at minimal storm force or even just below storm force as she reaches Newfoundland. Sea swells kicked up by Claudette are expected to be minimal as Claudette is a small and weak circulation.

2015 Atlantic Hurricane Season Birdseye Discussion #33A (Special Update)

By: NCHurricane2009, 2:43 PM GMT on July 13, 2015

...MONDAY JULY 13 2015 10:30 AM EDT...
Invest 92-L offshore of the mid-Atlantic United States appears to be rapidly organizing into a tropical cyclone. Therefore I have upgraded it to a special feature on this blog...see special feature section below for additional detials on this developing situation.

An upper vortex centered just north of the Bahamas is enhancing the poleward upper outflow over the southern part of a tropical wave moving through the central Caribbean Sea. This has resulted in an area of organized thunderstorms in the southern Caribbean Sea this morning. Will look at computer model upper-level wind forecasts during my full blog update tonight to determine if this is another area at risk for tropical development.

...SPECIAL FEATURE INVEST 92-L...
Current Prognosis...As of 1345Z visible satellite imagery suggests the center of 92-L is located at 37.2N-68.5W and is moving northeastward. Overnight a circular flare up of thunderstorms has developed and since then has persisted over and northeast of the center and therefore appears to be developing into a tropical cyclone.

Atmospheric Outlook for the Forecast Period...While steered by the frontal depression over the Ohio Valley and another frontal cyclone to follow behind...Invest 92-L will accelerate northeastward toward the Atlantic Canada coast in the next 48 hours. 92-L has been tracking to the right of last night's 18Z GFS model forecast...and therefore my forecast points below are based on a rightward adjustment of last night's 18Z GFS run. Warm air advection ahead of the Ohio Valley frontal depression has increased the upper ridging over 92-L which has increased the favorability of upper winds over the system. However after 24 hours the shortwave upper trough associated with the Ohio Valley system will approach from the west and introduce some southwesterly shear but also help transition this system to a non-tropical remnant gale supported by upper divergence on the east side of the shortwave.

Thermodynamic Outlook for the Forecast Period...By tomorrow morning 92-L will be moving into waters below 26 deg C...which will help transition this system from tropical to non-tropical as it nears the Atlantic Canada coast.

12 Hr Forecast (0000Z Jul 14)...50 mph max sustained wind tropical storm centered at 38.5N-67W

36 Hr Forecast (0000Z Jul 15)...45 mph max sustained wind non-troipcal gale centered just southeast and just offshore of Nova Scotia at 44N-59W.

2015 Atlantic Hurricane Season Birdseye Discussion #33

By: NCHurricane2009, 3:17 AM GMT on July 13, 2015

...SUNDAY JULY 12 2015 11:17 PM EDT...
Divergence on the east side of a shortwave upper trough moving offshore from North Carolina (marked by a blue-dashed line in the atmospheric features chart below) has produced a 1012 mb surface low along a frontal zone just offshore. Due to a well-defined spin and clumps of thunderstorms firing in the east half of the circulation...the 1012 mb low has been upgraded to tropical disturbance Invest 92-L.

While steered by the 1013 mb frontal depression over the Ohio Valley and another frontal cyclone to follow behind...Invest 92-L is expected to accelerate northeastward toward the Atlantic Canada coast in the next 48 hours. Upper-level winds could become a little more favorable for development over the next 24 hours as warm air advection ahead of the 1013 mb Ohio Valley depression increases upper ridging over 92-L and causes the less favorable cool core shortwave upper trough near 92-L to dissipate. After 24 hours 92-L will be moving into waters below 26 deg C...therefore the most likely timeframe for 92-L to become a tropical cyclone is the next 24 hours. I am not upgrading 92-L to a special feature on this blog unless it produces a deep burst of storms within the next 24 hours.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1200Z and 1321Z-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 temperature isotherms at http://www.nhc.noaa.gov/satellite.php...the site from which the above thermo chart is generated from...are currently outdated. Therfore I have approximated the 26 deg C isotherm in the above chart using the sea-surface temperature maps available at www.wunderground.com/hurricane. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).


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

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