NCHurricane2009's Blog

2014 Atlantic Hurricane Season Birdseye Discussion #50A (Special Update)

By: NCHurricane2009, 11:23 AM GMT on July 31, 2014

...THURSDAY JULY 31 2014 7:25 AM EDT...
Since discussion #50 last evening...tropical disturbance Invest 93-L approaching the Lesser Antilles has developed an increase in thunderstorms across the southern half of the circulation and therefore tropical cyclone formation is once again possible before this system crosses the Lesser Antilles during the next 48 hours. This system may become a tropical cyclone before my next full blog update tonight. Visit www.nhc.noaa.gov for the lastest information on 93-L...including any watches or warnings...should it become a tropical cyclone later today.

Return to full discussion #50 for the latest assessment on the Atlantic tropics...which includes a discussion of the tropical wave southwest of the Cape Verde Islands and east of 93-L which is also at risk of tropical cyclone development over the next few days.

2014 Atlantic Hurricane Season Birdseye Discussion #50

By: NCHurricane2009, 2:03 AM GMT on July 31, 2014

...WEDNESDAY JULY 30 2014 10:04 PM EDT...
Tropical disturbance Invest 93-L approaching the Lesser Antilles is receiving a double punch of dry air...one from the northeast while it remains under light northeasterly shear from the upper anticyclone to its north...and one to the west. The dry air to the west was previously expected to diminish after the inverted upper trough to the west has dissipated in the last 24 hours. Instead...this dry air is a bit stronger than 24 hours ago. Therefore I have dropped Invest 93-L as a special feature on this blog as I now expect it will not develop due to dry air.

The tropical wave south-southwest of the Cape Verde Islands is in a moisture surge more substantial than when Invest 93-L was at this same position about 72 hours ago. Therefore I continue to maintain this tropical wave as a special feature with my current expectation that it will become a tropical cyclone. See special feature section below for additional details.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_30_2014_2045Z_zps4353d86c.png
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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_30_2014_2045Z_Thermo_zps2de71926.png
This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

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

...SPECIAL FEATURE...TROPICAL WAVE SOUTH-SOUTHWEST OF THE CAPE VERDE ISLANDS...
Current prognosis...A tropical wave continues to become slowly better organized and is presently at a location south-southwest of the Cape Verde Islands. The developing cyclonic circulation seen in satellite animations has been upgraded to a 1011 mb surface low in the vicinity of 10N-30W as of 1800Z by the NHC TAFB.

Atmospheric Outlook for the Forecast Period...A 1029 mb surface subtropical ridge lies to the north which is expected to push this system west thru the forecast period. The tropical upper ridge to the north remains split into a pair of upper anticyclones by the deep-layered 1015 mb vortex located just south of the Azores...one marked as a blue H to the north of 93-L and the other marked as a blue H over Morocco in the above atmo chart. An inverted upper trough (marked by blue-dashed line) lies just north-northwest of this tropical wave in between the two upper anticyclones. Computer models suggest this inverted upper trough will move westward at a pace similar to the tropical wave's westward track...which will keep this tropical wave in close proximity to the less favorable inverted upper trough early in the forecast period. However this inverted upper trough maybe helping instead of hurting this tropical wave while keeping it below favorable upper divergence between upper southeasterlies on its east side and mainstream upper easterlies on the south side of the tropical upper ridge the inverted upper trough is embedded within. Later in the forecast period...models suggest the inverted upper trough will diminish and become replaced by upper easterly flow on the south side of the aformentioned tropical upper ridge. Such easterly shear may allow dry air intrusion from the northeast to push into the circulation similar to what has happened with 93-L. Therefore my updated forecast below develops this system at a cautious pace. However I believe this tropical wave is at a lower risk of dry air intrustion compared to 93-L as it is embedded in a more substantial moisture surge than when Invest 93-L was at this same position about 72 hours ago.

Thermodynamic Outlook for the Forecast Period...The forecast track will take this system over 27 to 28 deg C waters thru the forecast period...plenty warm for tropical development. The above thermo chart shows this system in a moisture surge with plenty of dry Saharan air to the north and west that lies ahead. The question is if this tropical wave will seperate from the moisture plume and eventually suffer dry Saharan air intrustion from the northeast due to light easterly shear its expected to encounter later in the forecast period. However as stated above...this tropical wave seems to be at a lower risk of dry air intrustion compared to previous wave 93-L as it is embedded in a more substantial moisture surge than when Invest 93-L was at this same position about 72 hours ago.

24 Hr Forecast (0000Z August 1)...Tropical low centered near 10N-35W.

48 Hr Forecast (0000Z August 2)...35 mph max sustained wind tropical depression centered near 10N-40W.

72 Hr Forecast (0000Z August 3)...40 mph max sustained wind tropical storm centered near 10N-45W.

96 Hr Forecast (0000Z August 4)....45 mph max sustained wind tropical storm centered near 10N-50W.

120 Hr Forecast (0000Z August 5)...50 mph max sustained wind tropical storm centered near 10N-55W.

2014 Atlantic Hurricane Season Birdseye Discussion #49

By: NCHurricane2009, 2:59 AM GMT on July 30, 2014

...TUESDSAY JULY 29 2014 11:05 PM EDT...
After nearly becoming a tropical cyclone...tropical wave Invest 93-L currently midway between the Lesser Antilles and Cape Verde Islands is suffering dry air intrusion due to light northeasterly wind shear. Therefore I have downgraded my forecast for this system and the organizing tropical wave south-southeast of the Cape Verde Islands as this tropical wave could also suffer from the same dynamics currently affecting 93-L. See both special feature sections below for an updated assessment and forecast for both tropical waves.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_29_2014_2045Z_zps957b906d.png
This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1921Z-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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_29_2014_2045Z_Thermo_zpsc5b84d4f.png
This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

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

...SPECIAL FEATURE...TROPICAL WAVE INVEST 93-L...
Current prognosis...As of 0000Z infrared satellite imagery suggested the tropical wave continues to stay organized around a surface low pressure spin located at 9N-41W. The tropical upper ridge to the north has become split into a pair of upper anticyclones by the deep-layered 1016 mb vortex over the Azores...one marked as a blue H to the north of 93-L and the other marked as a blue H over southern Morocco in the above atmo chart. The upper anticyclone due north of the system is producing light northeasterly vertical shear over the system. Even though this shear is light in nature...it has been enough to allow the dry Saharan air to the north to infiltrate into the circulation from the northeast. The system now consists of weakening spiral bands of showers and thunderstorms due to the dry air intrusion.

Atmospheric Outlook for the Forecast Period...A 1028 mb surface subtropical ridge lies to the north. This ridge has a 1016 mb deep-layered vortex over the Azores embedded in it. By connecting the deep-layered vortex to the series of upper vortices (blue Ls in the above atmo chart) to the southwest...a tropical upper tropospheric trough (TUTT) is present from the Azores all the way toward the Caribbean Sea. The TUTT is expected to last thru the forecast period...especially as the TUTT gets re-enforced as the 1016 mb deep-layered vortex retrogrades southwestward around the 1028 mb surface ridge and NW Atlantic upper anticyclone. Due to the recent dry air intrusion due to the light northeasterly shear...my updated forecast below delays development into a tropical cyclone until this system finds haven from shear while sliding beneath a weak upper anticyclone to develop east of the Lesser Antilles expected to replace the inverted upper trough (blue dashed line) currently west of 93-L. My updated forecast track below is a significant southward adjustment from the previous as this system is now less likely to become strong/tall enough to be pulled northward by TUTT features. This more southward track will cause this system to collide with a TUTT upper vortex forecast to sprawl over the Bahamas and Caribbean toward the end of the forecast...which is why I cap development at the end of my updated forecast with the potential for this system to become sheared by the southeastern quadrant of the TUTT upper vortex.

Thermodynamic Outlook for the Forecast Period...The forecast track will take this system over 27 to 29 deg C waters thru the forecast period...plenty warm for tropical development. Above thermo chart shows the tropical wave is in an east-west belt of moisture to the south of dry Saharan air. This dry air currently makes a southward dip in two places. The southward dip to the west of the tropical wave is a collection of dry air below the non-divergent environment below an inverted upper trough (blue dashed line west of the tropical wave in the above atmo chart). This inverted upper trough over the next 48 hours is expected to weaken and shift north while joining the TUTT to the north...which will allow a weak upper anticyclone in its place east of the Lesser Antilles (and any lift caused by upper divergence of the upper anticyclone will promote some moistening). The second southward dry air dip punches into the northeast half of the circulation of this tropical wave due to the light northeasterly shear mentioned in the above current prognosis section. However by 48 hours this system will be under less shear below the weak upper anticyclone east of the Lesser Antilles...with the current assumption that the reduction in shear will end the dry air problems for this system.

24 Hr Forecast (0000Z July 31)...Tropical low centered near 9N-46W.

48 Hr Forecast (0000Z August 1)...35 mph max sustained wind tropical depression centered near 9N-51W.

72 Hr Forecast (0000Z August 2)...45 mph max sustained wind tropical storm centered near 10N-56W.

96 Hr Forecast (0000Z August 3)...50 mph max sustained wind tropical storm centered near 11N-61W crossing the southern Lesser Antilles and under southerly vertical wind shear.

120 Hr Forecast (0000Z August 4)...45 mph max sustained wind tropical storm in the southeastern Caribbean centered near 12N-66W under southerly vertical shear.

...SPECIAL FEATURE...TROPICAL WAVE SOUTH-SOUTHEAST OF THE CAPE VERDE ISLANDS...
Current prognosis...A tropical wave has become a little better organized over the last 24 hours at a location south-southeast of the Cape Verde Islands...with the current twist in the assoicated cloudiness suggesting a weak circulation in the formative stages in the proximity of 10N-25W.

Atmospheric Outlook for the Forecast Period...A 1028 mb surface subtropical ridge lies to the north which is expected to push this system west on the heels of Invest 93-L thru the forecast period. The tropical upper ridge to the north has become split into a pair of upper anticyclones by the deep-layered 1016 mb vortex over the Azores...one marked as a blue H to the north of 93-L and the other marked as a blue H over southern Morocco in the above atmo chart. An inverted upper trough (marked by blue-dashed line) lies just west of this tropical wave in between the two upper anticyclones. Computer models suggest this inverted upper trough will move westward at a pace similar to the tropical wave's westward track...which will keep this tropical wave in close proximity to the less favorable inverted upper trough early in the forecast period. Later in the forecast period...models suggest the inverted upper trough will diminish and become replaced by upper easterly flow on the south side of the aformentioned upper anticyclones. Such easterly shear may allow dry air intrusion from the northeast to push into the circulation similar to what is now happening with 93-L. My updated forecast below develops this system at a much slower pace than the previous due to the potential unfavorable inverted upper trough early in the forecast and potential for easterly shear/dry air intrusion later in the forecast period.

Thermodynamic Outlook for the Forecast Period...The forecast track will take this system over 27 to 28 deg C waters thru the forecast period...plenty warm for tropical development. Like Invest 93-L...the above thermo chart shows this system is in an east-west belt of moisture to the south of dry Saharan air. As the above atmo outlook mentions...their is potential later in the forecast period for easterly shear to allow some of this dry air to push into this system.

24 Hr Forecast (0000Z July 31)...Weak circulation centered near 10N-30W.

48 Hr Forecast (0000Z August 1)...Tropical low centered near 10N-35W.

72 Hr Forecast (0000Z August 2)...35 mph max sustained wind tropical depression centered near 10N-40W.

96 Hr Forecast (0000Z August 3)...40 mph max sustained wind tropical storm centered near 10N-45W.

120 Hr Forecast (0000Z August 4)....45 mph max sustained wind tropical storm centered near 10N-50W.

2014 Atlantic Hurricane Season Birdseye Discussion #48

By: NCHurricane2009, 4:48 AM GMT on July 29, 2014

...TUESDSAY JULY 29 2014 12:50 AM EDT...
The tropical wave west of the Cape Verde Islands has organized much faster than previously thought...and therefore has already been upgraded to Invest 93-L on the Naval Research Laboratory site of the US Navy and is likely to become a tropical cyclone at any time. The Lesser Antilles should monitor the progress of this system over the next few days as it has the potential to become a fairly strong tropical cyclone prior to reaching the islands. See the Invest 93-L special feature section below for additional details.

A tropical wave has entered the eastern tropical Atlantic southeast of the Cape Verde Islands from western Africa. This was the second tropical wave referred into the introduction section of earlier discussion #46. Because it too has become well organized...I have also upgraded it to a special feature on this blog with the expectation that it will become our next Atlantic tropical cyclone immediately behind Invest 93-L. See the second special feature section below for additional details.

The CMC computer model currently predicts rapid tropical cyclone development over the open ocean near 30N-50W beginning in 72 hours. By studying upper wind forecasts...this area will be experiencing supportive upper divergence between a western fracture of the deep-layered 1017 mb low currently in the NE Atlantic and the deep-layered 1026 mb ridge currently in the NW Atlantic. Because the CMC model is usually overly-aggressive in prediction of tropical cyclogenesis and no other models show such a solution...currently not considering this a possibility.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_28_2014_2345Z_zps5a1d72bc.png
This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1917Z-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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_28_2014_2345Z_Thermo_zpscff5dfcc.png
This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

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

...SPECIAL FEATURE...TROPICAL WAVE INVEST 93-L...
Current prognosis...A tropical wave axis with widespread showers and thunderstorms was analyzed by the NHC TAFB to be at 40-W longitude as of 1800Z earlier this evening. The circulation to the east of the wave axis has evolved into a rapidly organizing low pressure spin analyzed by the NHC TAFB to be at 1011 mb as of 1800Z earlier this evening. Judging by this evening's infrared satellite loops...this circulation was near 10N-34.5W as of 1945Z and near 10N-35.5W as of 2345Z...which is a rate of 1 deg W per 4 hours (or 6 deg W per 24 hours) upon which the track forecast below is initially based upon (I slowed my forecast track to about 5 deg W per 24 hours later on to stay closer...but still a little faster...than the reliable GFS model forecast). A tropical upper ridge (blue-zig-zag line to the north of the tropical wave in the above atmo chart) is providing a favorable low shear and enhanced outflow environment that is supporting the shower and thunderstorm activity. Given the observations of spiral banding in all quadrants of the circulation and the favorable environment...tropical cyclone formation is possible at any time now.

Atmospheric Outlook for the Forecast Period...A 1030 to 1026 mb surface subtropical ridge lies to the north. This ridge has a 1017 mb deep-layered vortex over the Azores embedded in it. By connecting the deep-layered vortex to the series of upper vortices (blue Ls in the above atmo chart) to the southwest...a tropical upper tropospheric trough (TUTT) is present from the Azores all the way toward the Caribbean Sea. To the northwest of the TUTT is a NW Atlantic upper ridge (marked by purple H) and upper trough/vortex over eastern North America (marked by blue L). These features are all expected to persist thru the forecast period...especially as the TUTT gets re-enforced while the 1017 mb deep-layered vortex retrogrades southwestward. My forecast below predicts this system to briskly develop and strengthen in the favorable low shear and enhanced outflow provided by the tropical upper ridge mentioned in the current prognosis section. The upper layers of the aforementioned deep-layered vortex may further enhance the poleward outflow of this system later in the forecast period. By the end of the forecast period...forecasting that this system will have developed a strong upper anticyclone breaking free from the tropical upper ridge...with this anticyclone breaking the TUTT into two upper vortices...with the two upper vortices flanking the anticyclone providing additional outflow enhacement. As far as track...forecasting this system to continue west under the influence of the 1030 to 1026 mb surface subtropical ridge...followed by a more west-northwest track later in the forecast period while the forecast strengthening tropical cyclone becomes tall enough to be pulled by the TUTT (my updated forecast track below begins the curve to the north a bit sooner as the forecast tropical cyclone is now expected to get stronger sooner). Beyond the forecast period as the TUTT splits into two upper vortices...expecting the western of such upper vortices to become parked in the vicinity of the Bahamas with the potential to pull the forecast strong tropical cyclone on a more northwestward track into the western Atlantic.

Thermodynamic Outlook for the Forecast Period...The forecast track will take this system over 26 to 28 deg C waters thru the forecast period...plenty warm for tropical development. Above thermo chart shows the tropical wave is in an east-west belt of moisture to the south of dry Saharan air. This dry air makes a southward dip in the environment ahead of the tropical wave while collecting below the non-divergent environment below an inverted upper trough (blue dashed line west of the tropical wave in the above atmo chart) embedded in the tropical upper ridge. However this inverted upper trough is in the process of dissipating...therefore still expecting this dry air to not be a factor in this system's development.

24 Hr Forecast (0000Z July 30)...45 mph max sustained wind tropical storm centered near 10N-41.5W

48 Hr Forecast (0000Z July 31)...65 mph max sustained wind tropical storm centered near 10N-46.5W.

72 Hr Forecast (0000Z August 1)...80 mph max sustained wind hurricane centered near 12.5N-51.5W.

96 Hr Forecast (0000Z August 2)...95 mph max sustained wind hurricane centered near 15N-56.5W.

120 Hr Forecast (0000Z August 3)...110 mph max sustained wind hurricane centered near 17.5N-61.5W striking the northern Lesser Antilles

...SPECIAL FEATURE...TROPICAL WAVE SOUTHEAST OF THE CAPE VERDE ISLANDS...
Current prognosis...A tropical wave has just exited the west African coast into the eastern tropical Atlantic waters southeast of the Cape Verde Islands. This system is becoming increasingly organized to suggest that a circulation may be forming in the vicinity of 10N-18W.

Atmospheric Outlook for the Forecast Period...A 1030 to 1026 mb surface subtropical ridge lies to the north which is expected to push this system west on the heels of Invest 93-L thru the forecast period. This system will be sharing the favorable tropical upper ridge in the region with Invest 93-L. Thru latent heat release of its thunderstorms...93-L is in the process of forming upper anticyclonic outflow within the upper ridge...with relatively lower pressures east of the emerging anticyclone resutling in an inverted upper trough marked as a blue-dashed line to the east of 93-L and to the west of this system in the above atmo chart. With the forecast track below keeping this system close to the vicinity of the less favorable inverted upper trough...and with the current lack of computer model support...my forecast below develops this system slower than my forecast for 93-L. My forecast below maintains a westward track with little northward motion as the TUTT (tropical upper tropospheric trough) features are expected to be too far north thru the forecast period to be able to affect the steering (see atmo outlook section of 93-L for an introduction to the TUTT). Plus with my forecast intensity on the lower side...their is less potential for this system to become tall enough to be influenced steering-wise by TUTT features. Just beyond the forecast period...93-L could be an intense western Atlantic hurricane with a strong upper anticyclone...with the SE quadrant of such an anticyclone potentially providing unfavorable northerly shear for this system as it approaches the Lesser Antilles/Caribbean.

Thermodynamic Outlook for the Forecast Period...The forecast track will take this system over 26 to 28 deg C waters thru the forecast period...plenty warm for tropical development. Like Invest 93-L...the above thermo chart shows this system is in an east-west belt of moisture to the south of dry Saharan air.

24 Hr Forecast (0000Z July 30)...Well-organized tropical low centered near 10N-23W

48 Hr Forecast (0000Z July 31)...35 mph max sustained wind tropical depression centered near 10N-29W.

72 Hr Forecast (0000Z August 1)...45 mph max sustained wind tropical storm centered near 10N-34W.

96 Hr Forecast (0000Z August 2)...60 mph max sustained wind tropical storm centered near 10N-39W.

120 Hr Forecast (0000Z August 3)...70 mph max sustained wind tropical storm centered near 11N-44W.

2014 Atlantic Hurricane Season Birdseye Discussion #47

By: NCHurricane2009, 2:13 AM GMT on July 28, 2014

...SUNDAY JULY 27 2014 10:15 PM EDT...
Their is strong computer model support for tropical cyclogensis over the next few days from the tropical wave currently west of the Cape Verde Islands. Visible satellite imagery suggested a weak circulation near 30W-10N earlier this afternoon on the east side of the tropical wave...with showers and thunderstorms increasing over and west of this circulation as we have progressed into the evening. Therefore I have upgraded this tropical wave to a special feature on this blog with the exceptation that this will become our next tropical cyclone in the Atlantic Basin. See special feature section below for additional details.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_27_2014_2045Z_zpsbf831b82.png
This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1917Z-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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_27_2014_2045Z_Thermo_zps4a13fbc1.png
This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

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

...SPECIAL FEATURE...TROPICAL WAVE SOUTHWEST OF THE CAPE VERDE ISLANDS...
Current prognosis...A tropical wave axis with widespread showers and thunderstorms was analyzed by the NHC TAFB to be at 35-W longitude as of 1800Z. A weak circulation has been developing to the east of the wave axis...noted to be south of the Cape Verde Islands (near 25W-11N) as noted in the intro section of previous discussion #46...and now noted to be in the vicinity of 29W-11N as of 1800Z today. This is a rate of progression of 4 to 5 deg W per day upon which the forecast track below is largely based on. A tropical upper ridge (blue-zig-zag line to the north of the tropical wave in the above atmo chart) is providing a favorable low shear and enhanced poleward outflow environment that is supporting the shower and thunderstorm activity. Because the circulation is on the east side of the tropical wave axis...it lies on the eastern extent of the showers and thunderstorms such that most of the activity is over or west of the circulation center.

Atmospheric Outlook for the Forecast Period...A 1023 to 1028 mb surface subtropical ridge lies to the north. This ridge has a 1014 mb deep-layered vortex over the Azores embedded in the ridge. By connecting the deep-layered vortex to the series of upper vortices (blue Ls in the above atmo chart) to the southwest...a tropical upper tropospheric trough (TUTT) is present from the Azores all the way toward the Caribbean Sea. To the northwest of the TUTT is a NW Atlantic upper ridge (marked by blue H) and upper trough over eastern North America (marked by blue-dashed line). These features are all expected to persist thru the forecast period...especially as the TUTT gets re-enforced while the 1014 mb deep-layered vortex retrogrades southwestward. My forecast below predicts this system to continuously develop and strengthen in the favorable low shear and enhanced outflow provided by the tropical upper ridge mentioned in the current prognosis section. The upper layers of the aforementioned deep-layered vortex may further enhance the poleward outflow of this system later in the forecast period. Forecasting this system to continue west under the influence of the 1023 to 1028 mb surface subtropical ridge...followed by a more west-northwest track later in the forecast period while the forecast strengthening tropical cyclone becomes tall enough to be pulled by the TUTT.

Thermodynamic Outlook for the Forecast Period...The forecast track will take this system over 26 to 28 deg C waters thru the forecast period...plenty warm for tropical development. Above thermo chart shows the tropical wave is in an east-west belt of moisture to the south of dry Saharan air. This dry air makes a southward dip in the environment ahead of the tropical wave while collecting below the non-divergent environment below an inverted upper trough (blue dashed line west of the tropical wave in the above atmo chart) embedded in the tropical upper ridge. With computer models showing this inverted upper trough dissipating...expecting this dry air to not be a factor in this system's development.

24 Hr Forecast (1800Z July 28)...Circulation near 11N-33W with showers and thunderstorms over and west of the center but becoming better defined.

48 Hr Forecast (1800Z July 29)...Circulation near 11N-37W with showers and thunderstorms becoming more symmetrical about the center as the circulation becomes the dominant feature of the tropical wave.

72 Hr Forecast (1800Z July 30)...35 mph max sustained wind tropical depression centered near 11N-41W.

96 Hr Forecast (1800Z July 31)...50 mph max sustained wind tropical storm centered near 11N-45W.

120 Hr Forecast (1800Z August 1)...70 mph max sustained wind tropical storm centered near 12.5N-50W.

2014 Atlantic Hurricane Season Birdseye Discussion #46A (Special Update)

By: NCHurricane2009, 6:20 PM GMT on July 27, 2014

...SUNDAY JULY 27 2014 2:20 PM EDT...
The tropical wave west of the Cape Verde Islands is producing a weak circulation southwest of the islands at a location near 30W-10N as the 1200Z visible satellite image from Meteosat-9 below shows. The most recent runs of the CMC...GFS...and NAVGEM computer models forecast development from this feature over the next few days. I will be upgrading the tropical wave to a special feature with a forecast during my next full blog update later tonight. Interests in the Lesser Antilles should monitor the progress of this system over the next few days.

 photo TropicalWave_July27EarlyAfternoon_zps32b02492.png

2014 Atlantic Hurricane Season Birdseye Discussion #46

By: NCHurricane2009, 3:35 AM GMT on July 27, 2014

...SATURDAY JULY 26 2014 11:36 PM EDT...
The environment in the eastern tropical Atlantic will remain generally favorable for tropical development for the next few days with tropical upper ridging in the region expected to persist. However these favorable conditions are more on the marginal side with dry Saharan air intrusions in the area. Their are currently two tropical waves in the eastern tropical Atlantic. The first is west of the Cape Verde Islands which has become introduced into the National Hurricane Center Tropical Weather Outlook while producing a small rotating area of thunderstorms south of the islands for a brief period earlier today. The second is nearing the west Africa coast and will soon enter the eastern tropical Atlantic. The 12Z cycle of the CMC computer model suggests the second tropical wave will develop while the 12Z cycle of the GFS suggests the first wave will develop (the more recent 18Z GFS run shows neither wave developing). I am not upgrading either wave to a special feature at this time as neither show signs of imminent tropical cyclone development.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_26_2014_2045Z_zpsfff9c13a.png
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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_26_2014_2045Z_Thermo_zpsc65f79fc.png
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).

2014 Atlantic Hurricane Season Birdseye Discussion #45

By: NCHurricane2009, 11:52 PM GMT on July 25, 2014

...FRIDAY JULY 25 2014 7:55 PM EDT...
The environment in the eastern tropical Atlantic will remain generally favorable for tropical development for the next few days with tropical upper ridging in the region expected to persist. However these favorable conditions are more on the marginal side with a decrease in moisture in this region compared to 48 hours ago. The vigorous tropical wave previously over southwestern Mali is now nearing the west Africa coast and will enter the eastern tropical Atlantic in the next 24 hours. This tropical wave has not become better organized and computer model continue to predict no tropical development from this wave or anywhere in the Atlantic Basin for the next few days.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_25_2014_2045Z_zpsdc88604a.png
This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1913Z-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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_25_2014_2045Z_Thermo_zps08d2372a.png
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).

2014 Atlantic Hurricane Season Birdseye Discussion #44

By: NCHurricane2009, 12:24 AM GMT on July 25, 2014

...THURSDAY JULY 24 2014 8:25 PM EDT...
The remnant tropical wave of tropical depression two has entered the eastern Caribbean and is producing a shower and thunderstorm cluster south of Puerto Rico enhanced by split flow upper divergence between westerlies at the base of a cut-off upper trough to the northeast and easterlies on the south side of a Bahamas-to-eastern Caribbean upper ridge. Because the tropical wave has slowed its forward pace...it has about another 48 hours in the favorable low shear environment on the south side of the aforementioned upper ridge before it encounters less favorable upper vorticity expected to persist in the western Caribbean and southern Gulf of Mexico by 72 hours. Their are no signs of this tropical wave re-generating into a tropical cyclone...and no computer models suggest this system re-generating in the Atlantic basin.

The environment in the eastern tropical Atlantic remains favorable for tropical development with tropical upper ridging forecast to persist for the next few days. However these favorable conditions have become more marginal with a decrease in moisture in this region compared to 24 hours ago. A tropical wave has just moved off of Africa and into the eastern tropical Atlantic as marked in the lower-right of the atmospheric features chart below...however this wave is not impressive on satellite imagery and therefore is not expected to develop. Another tropical wave located over southwestern Mali in western Africa is producing a strong area of thunderstorms and will need to be monitored if it remains impressive upon entering the eastern tropical Atlantic in the next 48 hours.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_24_2014_2045Z_zpse5073948.png
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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_24_2014_2045Z_Thermo_zpsead0cf4e.png
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).

2014 Atlantic Hurricane Season Birdseye Discussion #43

By: NCHurricane2009, 12:03 AM GMT on July 24, 2014

...WEDNESDAY JULY 23 2014 8:03 PM EDT...
As expected tropical depression two has degenerated into a tropical wave while approaching the Lesser Antilles due to ingestion of dry Saharan air. Dry air is expected to prevent this system from re-generating into a tropical cyclone even though it will encounter a favorable upper ridge spanning from offshore of the SE US to the eastern Caribbean in the next 48 hours. By 72 hours upper vorticity persisting in the Gulf of Mexico and western Caribbean should prevent re-genesis of this system as it enters a more moist environment.

Elsewhere...the environment in the eastern tropical Atlantic has become more favorable for tropical development with an increase in moisture and tropical upper ridging that is expected to persist for the next few days. However satellite imagery over Africa does not show any potent tropical waves that could take advantage of this environment...and computer model runs currently show no tropical development from any African tropical waves during the next few days.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_23_2014_2045Z_zpsd4f1b5ff.png
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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_23_2014_2045Z_Thermo_zps1179ee3e.png
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).

2014 Atlantic Hurricane Season Birdseye Discussion #42

By: NCHurricane2009, 10:57 PM GMT on July 22, 2014

...TUESDAY JULY 22 2014 7:00 PM EDT...
Tropical depression two likely to dissipate into a remnant wave before reaching the Lesser Antilles. See special feature section below for additional details.


...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_22_2014_2045Z_zpsa9301502.png
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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_22_2014_2045Z_Thermo_zps9af6573d.png
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 are currently not functioning properly from the satellite product from which the above graphic is derived. See the thermodynamics chart from previous discussion #41 for a view of latest sea surface temperatures. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

...SPECIAL FEATURE...TROPICAL DEPRESSION TWO...
Current prognosis...As of the 5 PM EDT National Hurricane Center (NHC) advisory...the depression was centered at 12.9N-49.6W while continuing on a brisk west to west-northwest track while embedded in deep-layered eastery flow south of the 1025 mb Atlantic subtropical ridge at the surface and south of the tropical upper ridge as marked by a blue H to the north of the depression in the above atmospheric features chart. Even though the depression is in a low shear environment in this deep-layered easterly flow...the distribution of showers and thunderstorms is becoming increasingly limited to the south side of the circulation as the system begins encoutering the vast dry Saharan air layer to the north.

Atmospheric Outlook for the Forecast Period...Computer models continue to suggest the inverted upper trough to the northeast of the depression (marked by blue dashed line up and to the right of TD 2 in the above atmo chart) will move quickly westward around the anticyclonic center of the tropical upper ridge (makred by blue H to the north of TD 2 in the above atmo chart). However the depression's equally fast westward track will not allow this unfavorable inverted upper trough to catch up to the depression thru the forecast period. Model runs also show the 1025 mb surface ridge to the north of the depression staying intact thru the forecast period.

Thermodynamic Outlook for the Forecast Period...Sea surface temperatures will become increasingly warm along the forecast track shown below. However the thermo chart above shows that the depression is likely to suffer from the expansive region of dry Saharan air to the north and west. This dry air mass reaches the low-latitudes all the way to South America in the environment ahead of the depression.

 photo Jul_22_2014_TD_Two_Forecast_zps5e781a74.png

Track Forecast...The tropical cyclone will be steered in deep-layered easterly flow south of the tropical upper ridge and south of the 1025 mb surface subtropical ridge thru the forecast period. Latest visible satellite observations suggest the track has slowed to more of a 1 deg W longitude per 4 hours. Comparing the fix from yesterday and today's 5 PM EDT NHC advisory package...the depression is also making a 1.5N latitude per 24 hour progression towards the north. Therefore my updated forecast track below moves the depression about 1 deg W per 4 hours (or 6 deg W per 24 hours) and another 1.5N latitude jump during the next 24 hours.

Intensity Forecast...My forecast calls for dissipation of the tropical cyclone by 24 hours based on the observations of dry air noted in the above thermodynamic outlook section.

Impact Forecast...With the expectation this system remains a small and weak tropical cyclone thru the forecast period...no significant impacts from this system are expected.

2014 Atlantic Hurricane Season Birdseye Discussion #41

By: NCHurricane2009, 12:50 AM GMT on July 22, 2014

...MONDAY JULY 21 2014 9:00 PM EDT...
The circulation at the south end of the tropical wave west-southwest of the Cape Verde Islands has become the second tropical depression of the 2014 Atlantic Hurricane Season. See special feature section below for additional details on this system.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_21_2014_2045Z_zps0ba198d6.png
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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_21_2014_2045Z_Thermo_zpsaaaaa4c0.png
This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

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

...SPECIAL FEATURE...TROPICAL DEPRESSION TWO...
Current prognosis...The circulation at the south end of the tropical wave west-southwest of the Cape Verde Islands has become further organized to be upgraded to tropical depression two. As of the 5 PM EDT National Hurricane Center (NHC) advisory...the depression was centered at 11.6N-43.8W while on a brisk westward track while embedded in deep-layered eastery flow south of the 1026 mb Atlantic subtropical ridge at the surface and south of the tropical upper ridge as marked by a blue H to the north of the depression in the above atmospheric features chart. Visible satellite animation suggests the depression is moving at nearly 1 deg W per 3 hours with the center near 44W by 2115Z (5:15 PM EDT) and center near 43W at 1815Z (2:15 PM EDT).

Atmospheric Outlook for the Forecast Period...Computer models continue to suggest the inverted upper trough to the northeast of the depression (marked by blue dashed line up and to the right of TD 2 in the above atmo chart) will move quickly westward around the anticyclonic center of the tropical upper ridge (makred by blue H to the north of TD 2 in the above atmo chart). However the depression's equally fast westward track will not allow this unfavorable inverted upper trough to catch up to the depression thru the forecast period. Model runs also show the 1026 mb surface ridge to the north of the depression staying intact thru the forecast period.

Thermodynamic Outlook for the Forecast Period...Sea surface temperatures will become increasingly warm along the forecast track shown below. However the thermo chart above shows that the depression is likely to suffer from the expansive region of dry Saharan air to the north and west. This dry air mass reaches the low-latitudes all the way to South America beyond 50W. The current assumption in my forecast below is that the tropical depression will begin to disspate from dry air ingestion once it crosses 50W longitude.

 photo Jul_21_2014_TD_Two_Forecast_zpsdd0d667c.png

Track Forecast...The tropical cyclone will be steered in deep-layered easterly flow south of the tropical upper ridge and south of the 1026 mb surface subtropical ridge thru the forecast period. My track forecast above is a compromise between the NHC's slower west-northwest forecast track and much more rapid straight west track spanning 1 deg W longitude per 3 hours (or 8 deg W longitude per 24 hours) observable in latest visible satellite imagery as discussed in the above current prognosis section.

Intensity Forecast...The NHC and my forecast above currently assume this system will not strengthen further. However up-to-the minute lastest infrared satellite imagery suggests the depression is firing off a ball of stronger thunderstorms near the center..and so it is possible the depression strengthens into a weak tropical storm within the next 24 hours before weakening from dry air ingestion later on. My forecast calls for dissipation of the tropical cyclone by 48 hours based on the observations of dry air noted in the above thermodynamic outlook section.

Impact Forecast...With the expectation this system remains a small and weak tropical cyclone thru the forecast period...no significant impacts from this system are expected.

2014 Atlantic Hurricane Season Birdseye Discussion #40A (Special Update)

By: NCHurricane2009, 6:29 PM GMT on July 21, 2014

...MONDAY JULY 21 2014 2:35 PM EDT...
A tropical depression appears to be forming at 11.5N-43W this afternoon as the low pressure center as the south end of the tropical wave southwest of the Cape Verde Islands continues to become better organized. This circulation has moved faster to the west than previously anticipated such that the unfavorable inverted upper trough to the northeast is no longer expected to catch up to it. This system is also doing well against the dry Saharan air to the north. This system has been upgraded to Invest 92-L on the Naval Research Laboratory Site of the US Navy and has been given a high chance of tropical cyclone formation in the latest National Hurricane Center Tropical Weather Outlook. The outlook states that interests in the southern Lesser Antilles should monitor the progress of this system over the next few days.

During my next full blog update later today...I plan to upgrade this system to a speical feature with the assumption that it will eventually become a tropical cyclone.

2014 Atlantic Hurricane Season Birdseye Discussion #40

By: NCHurricane2009, 11:09 PM GMT on July 20, 2014

...SUNDAY JULY 20 2014 7:10 PM EDT...
The tropical wave southwest of the Cape Verde Islands continues to feature a low pressure spin at the south end of its axis which has become a little better organized and is currently at 1013 mb. The tropical wave has become introduced into the National Hurricane Center Tropical Weather Outlook and has found a more favorable atmospheric environment while escaping the inverted upper trough (marked as blue-dashed line to the northeast of the tropical wave in the atmospheric features chart below). However tropical cyclone formation from this tropical wave is not likely as it will encounter dry Saharan air to the northwest and as the inverted upper trough is expected to catch up to the tropical wave while shifting westward around the south side of the tropical upper ridge in the eastern Atlantic (marked as blue H and blue-zig-zag line to the northwest of the tropical wave).

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_20_2014_1915Z_zps04f23cd6.png
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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_20_2014_1915Z_Thermo_zps02824679.png
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).

2014 Atlantic Hurricane Season Birdseye Discussion #39

By: NCHurricane2009, 1:18 AM GMT on July 20, 2014

...SATURDAY JULY 19 2014 9:18 PM EDT...
The vigorous tropical wave previously over and south of the Cape Verde Islands is currently southwest of the Cape Verde Islands. An inverted upper trough has formed within the eastern tropical Atlantic upper ridge stemming from the cut-off upper vorticity currently in the northeastern Atlantic. The south end of the tropical wave has formed a 1014 mb low pressure spin with showers and thunderstorms perhaps while enhanced by upper divergence on the east side of the inverted upper trough. However not expecting tropical development due to dry Saharan air to the northwest seen in water vapor satellite imagery and the fact that the tropical wave is likely to become aligned with the non-divergent region of the inverted upper trough as the upper trough also travels west.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_19_2014_2045Z_zps46410210.png
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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_19_2014_2045Z_Thermo_zps23cd894d.png
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).

2014 Atlantic Hurricane Season Birdseye Discussion #38

By: NCHurricane2009, 12:34 AM GMT on July 19, 2014

...FRIDAY JULY 18 2014 8:34 PM EDT...
Showers and thunderstorms persist southwest of Bermuda while supported by upper divergence between a persistent upper vortex and the surrounding flow around adjacent upper level features. However this activity should diminish as the upper vortex is diminshing. The weather in this region is also controlled by a surface frontal boundary moving offshore of the east coast of the United States that is supported by divergence on the east side of a longwave upper trough regime that has persisted over eastern North America over the last days. A frontal depression persists offshore of South Carolina that is currently 1018 mb. Expect that the shortwave upper trough currently over the central United States...currently a part of the aforementioned longwave upper trough regime...to swing east and support this frontal depression as a non-tropical feature that will eventually accelerate north and then east across the east US coast and eventually the Atlantic Canada coasts.

The tail of the frontal boundary mentioned in the above paragraph extends across the US Gulf coast. Showers and thunderstorms are pushing southward toward the northern Gulf of Mexico as the tail of the front and an upper ridge (associated with the warm air ahead of the front) push south. As the upper ridge settles across the northern Gulf...it will be capable of providing low vertical shear and outflow enhancement supportive for tropical development along the surface front. However forecasts from the National Weather Service show that the front will not sag into the northern Gulf. Moreover...the shortwave upper trough associated with the 994 mb frontal cyclone over south-central Canada is expected to rapidly dive southeast and tear into the favorable upper ridge by 72 hours. Therefore tropical development is not expected in the northern Gulf.

The vigorous tropical wave previously southeast of the Cape Verde Islands is passing over and south of the islands today. Thermodynamic conditions in the eastern tropical Atlantic have improved with the warming of water temps and this tropical wave teaming up with the tropical wave midway between the Cape Verde Islands and Lesser Antilles moisentining out the dry Saharan air as shown in water vapor satellite animation. Atmospheric conditions in the eastern tropical Atlantic are also currently favorable with an upper ridge in the region. However...the GFS computer model continues to forecast the development of an unfavorable inverted upper trough within the upper ridge over the next few days stemming from the cut-off upper vorticity currently in the northeastern Atlantic. Therefore not expecting development from this tropical wave with a high likelihood of the tropical wave becoming phased with the unfavorable inverted upper trough.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_18_2014_2045Z_zps9823f893.png
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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_18_2014_2045Z_Thermo_zps18d4ff2f.png
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).

2014 Atlantic Hurricane Season Birdseye Discussion #37

By: NCHurricane2009, 1:09 AM GMT on July 18, 2014

...THURSDAY JULY 17 2014 9:10 PM EDT...
Showers and thunderstorms previously south of Bermuda have shifted to a location southwest of Bermuda while becoming supported by upper divergence between a persistent upper vortex to the west and the surrounding flow around adjacent upper level features. The weather in this region is also enhanced by a surface frontal boundary moving offshore of the east coast of the United States that is supported by divergence on the east side of a longwave upper trough regime that has persisted over eastern North America over the last days. A 1014 mb frontal depression has formed offshore of South Carolina. Expect that the shortwave upper trough currently over the central United States...currently a part of the aforementioned longwave upper trough regime...to swing east and support this frontal depression as a non-tropical feature that will eventually accelerate north and then east across the east US coast and eventually the Atlantic Canada coasts.

The vigorous tropical wave over interior western Africa has emerged into the eastern tropical Atlantic southeast of the Cape Verde Islands during the last 24 hours. Thermodynamic conditions in the eastern tropical Atlantic have improved with the warming of water temps and this tropical wave teaming up with the tropical wave midway between the Cape Verde Islands and Lesser Antilles moisentining out the dry Saharan air as shown in water vapor satellite animation. Atmospheric conditions in the eastern tropical Atlantic are also currently favorable with an upper ridge in the region. However...the GFS computer model continues to forecast the development of an unfavorable inverted upper trough within the upper ridge over the next few days stemming from the cut-off upper vorticity currently in the northeastern Atlantic. Therefore not expecting development from this tropical wave with a high likelihood of the tropical wave becoming phased with the unfavorable inverted upper trough.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_17_2014_2045Z_zpsd9fe800c.png
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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_17_2014_2045Z_Thermo_zps51bb6e94.png
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).

2014 Atlantic Hurricane Season Birdseye Discussion #36

By: NCHurricane2009, 1:10 AM GMT on July 17, 2014

...WEDNESDAY JULY 16 2014 9:10 PM EDT...
Showers and thunderstorms persist south of Bermuda under the support of an upper ridge that is developing in relatively higher pressures between upper vorticity to the east and west. Their are no signs of additional development and computer models forecast no development. In addition upper winds will become less favorable in this area during the next 48 hours as upper vorticity to the east retrogrades westward into this area while the upper vorticity orbits around the 1032 mb deep-layered ridge that is located northeast of Bermuda.

Over the past day a vigorous tropical wave has moved from interior central to interior western Africa and will be emerging into the eastern tropical Atlantic from the African coast in about 48 hours. Thermodynamic conditions in the eastern tropical Atlantic have improved with the warming of water temps and the tropical wave currently southwest of the Cape Verde Islands moistening out the dry Saharan air as shown in water vapor satellite animation. Atmospheric conditions in the eatsern tropical Atlantic are also currently favorable with an upper ridge in the region. However...the GFS computer model forecasts the development of an inverted upper trough within the upper ridge in about 72 hours stemming from the cut-off upper vorticity currently in the northeastern Atlantic. Development of the tropical wave currently over interior western Africa will depend on how well-organized it is when it emerges into the Atlantic and whether or not it aligns with the forecasted unfavorable inverted upper trough.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_16_2014_2045Z_zps816c8a0a.png
This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1922Z-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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_16_2014_2045Z_Thermo_zpsbc225bfe.png
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).

2014 Atlantic Hurricane Season Birdseye Discussion #35

By: NCHurricane2009, 12:21 AM GMT on July 16, 2014

...TUESDAY JULY 15 2014 8:30 PM EDT...
A surface trough of low pressure with showers and thunderstorms persists south of Bermuda. The nearby upper vortex has split into one to the east and another to the north. A third upper vortex over the prior 2 days has moved from the area east of North Carolina to a location west of the surface trough. The surface trough has become supported by split flow divergence between the three upper vortices. The northern upper vortex is expected to continue north in advance of the deep-layered 1002 mb cyclone over eastern Canada...with the surface trough expected to also eventually move north while steered around the 1030 mb deep-layred ridge east of Bermuda. The CMC computer model remains the only model to evolve the surface trough into a circulation...but forecasts this circulation to move rapidly northward over the next 48 hours. However still monitoring this situation as models also forecast over the next 48 hours for a favorable upper ridge to form south of Bermuda in between the upper vortices currently east and west of the surface trough. Therefore their is potential for a southern fragment of the surface trough to linger behind and develop beneath the forecast upper ridge.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_15_2014_2045Z_zps4e732d3f.png
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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_15_2014_2045Z_Thermo_zps86d20d83.png
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).

2014 Atlantic Hurricane Season Birdseye Discussion #34

By: NCHurricane2009, 5:01 PM GMT on July 14, 2014

...MONDAY JULY 14 2014 1:00 PM EDT...
The tropical wave southwest of the Cape Verde Islands mentioned in previous discussion #33 has diminished while ingesting dry Saharan air to the north. Further development of this system is not expected.

A surface trough of low pressure has formed south of Bermuda with the support of split flow upper divergence between the north side of a nearby upper vortex and west side of a deep-layered ridge forming east of Bermuda. Over the next 48 hours...most of the upper vorticity is expected to shift north in advance of the deep-layered 993 mb cyclone over eastern Canada...followed by a northward track of the surface trough around the west side of the aforementioned deep-layered ridge. With the upper vorticity expected to be replaced by a favorable low shear environment around the deep-layered ridge...some tropical development of this system is possible and therefore Bermuda should monitor this system. Currently the showers and thunderstorms associated with the surface trough are poorly organized and the CMC computer model is currently the only model that hints at some development while showing the trough evolving into a circulation.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_14_2014_1215Z_zps2ff609ec.png
This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0600Z and 0724Z-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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_14_2014_1215Z_Thermo_zps28340e5c.png
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).

2014 Atlantic Hurricane Season Birdseye Discussion #33

By: NCHurricane2009, 6:50 PM GMT on July 13, 2014

...SUNDAY JULY 13 2014 2:50 PM EDT...
I am resuming daily blog updates now that I have returned from vacation overseas.

Visible satellite animation suggests a tropical wave southwest of the Cape Verde Islands is producing a semi-organized circulation in the vicinity of 7.5N-30W. This circulation is far south enough to dodge unfavorable thermodynamic conditions in the eastern tropical Atlantic (cooler waters and dry Saharan air). In additon...the pair of upper vortices in the western Atlantic (one east of North Carolina and one south of Bermuda) are expected to orbit each other and then shift north in advance of the 1000 mb deep-layered vortex currently over central Canada. This will allow the favorable tropical upper ridging to expand in the wake of the upper vortices. Therefore even though computer models forecast no tropical development from this or any other system during the next week...I believe their is some potential for slow development of this tropical wave as it approaches the southern Lesser Antilles during the next 3 to 4 days.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_13_2014_1215Z_zps2cb3f4ca.png
This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1200Z and 1332Z-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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_13_2014_1215Z_Thermo_zpsd969e0ae.png
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).

2014 Atlantic Hurricane Season Birdseye Discussion #32

By: NCHurricane2009, 10:07 PM GMT on July 05, 2014

...SATURDAY JULY 5 2014 6:07 PM EDT...
Arthur as expected has transitioned into a non-tropical gale that is currently producing storm force winds over large sections of Nova Scotia...and will affect western Newfoundland tomorrow.

This is my final blog update from a hotel in Spain as I will travel to Egypt tomorrow for a stay lasting thru the 12th. As such my internet access to make blog updates will be rather limited...and it is likely that I will not be able to do blog updates during this timeframe. Current computer model runs suggest no tropical cyclone formation in the Atlantic during the next week as the thermodynamics chart below shows plenty of unfavorable Saharan dry air at the low-latitudes...and wind shear in the low-latitudes is forecast by models to remain high wherever moisture is present. In the mid-latitudes...a 1019 mb depression has formed offshore of South Carolina along the front trailing from the remnant of Arthur. This system will remain quasi-stationary in the near-term while trapped between 1024 mb eastern US ridge and 1031 mb Atlantic subtropical ridge. Although current computer model runs do not develop it...over the next 48 hours a favorable shear-reducing and outflow enhancing upper ridge is forecast to develop in its region. If development were to occur...the system would be swept northeastward out to sea by the 1005 mb frontal depression over south-central Canada by 72 hours. Visit www.nhc.noaa.gov and or www.wunderground.com/tropical for the latest on the Atlantic tropics while I am absent thru the 12th.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_05_2014_1445Z_zpsd6b40b95.png
This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1200Z and 1328Z-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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_05_2014_1445Z_Thermo_zps696531c0.png
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).

2014 Atlantic Hurricane Season Birdseye Discussion #31

By: NCHurricane2009, 8:20 PM GMT on July 04, 2014

...FRIDAY JULY 4 2014 4:20 PM EDT...
After striking the North Carolina Outer Banks as a category 2 hurricane last night...Arthur has weakened to a category 1 but is poised to affect the Massachusetts coast with tropical storm winds late tonight and early tomorrow morning...and then is expected to strike Nova Scotia and parts of Newfoundland as a strong non-tropical gale during the later part of this upcoming weekend. Visit www.nhc.noaa.gov for the latest government forecasts and information on tropical storm and hurricane watches/warnings with this system. See special feature section below for my updated assessment of Arthur.

This blog update was done using internet access from a hotel in Spain. For Vacation...I am staying in Spain thru July 6...followed by a stay in Egypt from July 7 thru the 12th. As such my internet access to make blog updates will continue to be limited. The hotel in Spain should allow me to do blog updates thru July 6. Internet access in Egypt from the 7th thru 12th will be more limited...and it is likely that I will not be able to do blog updates during that time.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_04_2014_1445Z_zps891e6a16.png
This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1200Z and 1521Z-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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_04_2014_1445Z_Thermo_zps3df3e467.png
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 ARTHUR...
Current prognosis...As of the 2 PM EDT National Hurricane Center (NHC) advisory...the hurricane was centered at 38.5N-72.4W while moving rapdily to the northeast offshore of the northeastern United States coast. Late tonight and early tomorrow morning...the northwestern quadrant is likely to deliver a period of tropical storm force winds to the Massachusetts coastline.

Atmospheric Outlook for the Forecast Period...Arthur is in a narrow low-level ridge weakness between 1026 mb ridge to the west supported by convergence on west side of upper troughing that he is interacting with...and 1033 mb Atlantic subtropical ridge to the east. However the hurricane is plenty strong/tall enough to be accelerated northeastward through the narrowing low-level weakness by the aforementioned upper troughing. The upper troughing is increasing the southwesterly shear across Arthur and is aiding in transition of Arthur into a non-tropical gale.

Thermodynamic Outlook for the Forecast Period...Arthur has crossed the 26 deg C isotherm into cooler northwestern Atlantic waters...which will help in the transition of this system to non-tropical.

 photo Jul_4_2014_H_Arthur_Forecast_zps12727f08.png

Track Forecast...Although Arthur has tracked a bit to the left of previous track forecasts since the previous blog update...he is re-alinging with previous track forecats as visible satellite animation this afternoon shows the center tracking toward 40N-70W. Extrapolating the forward speed shown in visible satellite imagery between 1715Z and 1815Z suggests Arthur will be just northeast of 40N-70W by 8 PM EDT (0000Z) tonight. Therefore my updated track forecast for 8PM Friday (tonight) is just northeast of 40N-70W...which is a bit faster than my previous track forecast and also a bit faster than the latest NHC track forecast released at 11 AM EDT. Therefore I have also made my updated 8PM Saturday forecast point a bit faster than the NHC track forecast. A notable change for 8 PM Saturday is that the models...NHC...and I have shifted the 8 PM Saturday point leftward such that we now have Arthur over north-central Nova Scotia instead of south-central Nova Scotia. Latest model runs...such as GFS and CMC...now show Arthur amplifying a fragment of the upper troughing into an upper vortex that will hook him more northward thru 8 PM Saturday. The models then show Arthur and said upper vortex shifting more east-northeastward...followed by amplifcation of the remainder of the upper trough into another upper vortex that hooks him again more northward by Monday as the above NHC track forecast shows.

Intensity Forecast...Arthur has very precisely followed my previous intensity forecast by becoming a category 2 hurricane of 100 mph while sliding across the North Carolina Outer Banks...and is now weakening at a rate such that I have confidence to simply copy-paste my prevoius intensity forecast. The current weakening trend is a result of Arthur moving over waters below 26 deg C and a result of increasing southwesterly shear (mentioned at the end of the above atmo outlook section). The weakening rate however is not rapid as Arthur transitions into a vigorous non-tropical remnant low supported by divergence on the east side of upper troughing mentioned in the above atmo outlook section.

Impact Forecast...Impact swath is initialized based on the tropical storm wind field depicted in NHC's 11 AM EDT advisory...which is then extrapolated along the forecast track. Because of the leftward adjustment to the forecast track for 8 PM Saturday...the swath now predicts tropical storm force winds briefly clipping Massachusetts coastal real estate by late tonight/tomorrow early AM...which is why tropical storm warnings have been raised on Massachusetts coast within the last 24 hours. By late Saturday...the impact swath shows gale force winds affecting a large section of Nova Scotia. Western Newfoundland is expected to see gale force winds on Sunday.

2014 Atlantic Hurricane Season Birdseye Discussion #30

By: NCHurricane2009, 6:35 PM GMT on July 03, 2014

...THURSDAY JULY 3 2014 2:36 PM EDT...
Arthur has strengthened into a hurricane since my previous blog update...and remains on track to make a severe strike the North Carolina Outer Banks tonight and into tomorrow morning. During the later part of this upcoming weekend...Arthur is expected to strike Nova Scotia and parts of Newfoundland as a strong non-tropical gale. Visit www.nhc.noaa.gov for the latest government forecasts and information on tropical storm and hurricane watches/warnings with this system. See special feature section below for my updated assessment of Arthur.

This blog update was done using internet access from JFK airport in NYC. For Vacation...I am flying to Spain later this afternoon and staying in Spain thru July 6...followed by a stay in Egypt from July 7 thru the 12th. As such my internet access to make blog updates will be limited. The hotel in Spain may allow me to do blog updates thru July 6. Internet access in Egypt from the 7th thru 12th will be more limited...and it is likely that I will not be able to do blog updates during that time.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_03_2014_1445Z_zps17a15e11.png
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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_03_2014_1445Z_Thermo_zps1205b06f.png
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 ARTHUR...
Current prognosis...As of the 2 PM EDT National Hurricane Center (NHC) advisory...the hurricane was centered at 32.9N-78.3W while curving on a northeastward track on schedule. Some additional strengthening to a category 2 is forecast before the eye crosses the Outer Banks of North Carolina late this evening thru tomorrow morning. If Arthur indeed achieves category 2...this will be the first greater-than-category 1 hurricane in the Atlantic basin since Sandy in October 2012.

Atmospheric Outlook for the Forecast Period...Arthur is curving northeastward while rounding the west side of the 1035 mb Atlantic subtropical ridge and out ahead of incoming NE US/SE Canada upper trough/surface 993 mb frontal cyclone. Because the frontal cyclone is far north in relation to the hurricane...the hurricane will soon get caught into a narrowing low-level ridge weakness as the frontal cyclone passes by. However the hurricane is plenty strong/tall enough to be accelerated northeastward through the narrowing low-level weakness by upper-level troughing lingering from the NE US/SE Canada weather system. Arthur has another 12 hours under the safeguard of an upper ridge that is helping his upper outflow and keeping wind shear low...after which time interaction with the aforementioned upper troughing will increase westerly shear and aid in transition of Arthur into a non-tropical gale.

Thermodynamic Outlook for the Forecast Period...Sea surface temps early in the forecast period will be in the 28 to 30 deg C range...very supportive for additional tropical development. However by late Friday and this weekend...the tropical cyclone will have crossed the 26 deg C isotherm into cooler northwestern Atlantic waters...which will help in the transition of this system to non-tropical. The above thermo chart suggests that the patch of dry continental air that was northwest of Arthur has since been squeezed out between Arthur's storm canopy and a band of moisture associated with the cold front coming in from the west. It appears the dissipation of this dry air has finally allowed Arthur to intensify into a hurricane.

 photo Jul_3_2014_TS_Arthur_Forecast2_zps3499651e.png

Track Forecast...Arthur has done very well in following the previous track forecasts...and therefore both my track forecast and NHC track forecast have not changed since the previous blog update.

Intensity Forecast...Arthur has strengthened a little bit faster than I previously predicted in discussion #29. Therefore I have slightly increased my intensity forecast and now predict Arthur to become a category 2 hurricane with 100 mph max sustained winds later today. My updated intensity forecast is in general agreement with the NHC's intensity forecast released at 11 AM EDT. The intensity forecast shows weakening by Friday and Saturday as I expect the increasing westerly shear (mentioned at the end of the above atmo outlook section) to begin affecting Arthur. The weakening rate however will not be rapid as Arthur transitions into a vigorous non-tropical remnant low supported by divergence on the east side of upper troughing mentioned at the end of the above atmo outlook.

Impact Forecast...Impact swath is initialized based on the tropical storm wind field depicted in NHC's 11 AM EDT advisory...which is then extrapolated along the forecast track. The impact swath predicts tropical storm winds reaching all of the North Carolina coast later today (Thursday) thru early Friday...with crippling hurricane conditions expected over the Outer Banks with the center forecast to cross over the Banks. All storm force winds are still predicted to pass offshore of New England. By late Saturday...the impact swath shows gale force winds affecting a large section of Nova Scotia. Western Newfoundland is expected to see gale force winds on Sunday.

2014 Atlantic Hurricane Season Birdseye Discussion #29

By: NCHurricane2009, 5:29 AM GMT on July 03, 2014

...THURSDAY JULY 3 2014 1:30 AM EDT...
Tropical Storm Arthur is currently located offshore of northeastern Florida and Georgia...and is on a track toward the North Carolina Outer Banks. The storm remains well organized and is likely to become the first hurricane of the Atlantic season. During the later part of this upcoming weekend...Arthur is expected to strike Nova Scotia and parts of Newfoundland as a strong non-tropical gale. Visit www.nhc.noaa.gov for the latest government forecasts and information on tropical storm and hurricane watches/warnings with this system. See special feature section below for my updated assessment of Arthur.

Elsewhere...satellite imagery shows another tropical wave with curved storm banding emerging from the west coast of Africa. However this system is likely to incur the same unfavorable thermodynamic parameters as the tropical wave currently southwest of the Cape Verde Islands did (waters below 26 deg C at its north half and ingestion of dry Saharan air seen in water vapor to its northwest). None of the computer models develop this tropical wave. Thunderstorms in the northeastern Gulf of Mexico during the previous afternoon were caused by split flow upper divergence between the northwest quadrant of the upper anticyclone over Arthur and northeast quadrant of a cut-off upper vortex in the western Gulf left behind days ago by the upper trough Arthur is about to interact with. These thunderstorms have since died down this evening and development is not expected.

On a final note...I am currently headed out on vacation. I am flying to Spain tomorrow afternoon and staying in Spain thru July 6...followed by a stay in Egypt from July 7 thru the 12th. As such my internet access to make blog updates will be limited. I plan to release another blog update from JFK airport in NYC tomorrow afternoon...and the hotel in Spain may allow me to do blog updates thru July 6. Internet access in Egypt from the 7th thru 12th will be more limited...and it is likely that I will not be able to do blog updates during that time.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_02_2014_2045Z_zps545bd968.png
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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_02_2014_2045Z_Thermo_zps31d6e49d.png
This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

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

...SPECIAL FEATURE...TROPICAL STORM ARTHUR...
Current prognosis...As of the 11 PM EDT National Hurricane Center (NHC) advisory...the tropical storm was centered at 30.6N-79.1W while continuing on a northward heading. The tropical storm remains well-organized since the previous update...with the intermittent apperance of an eye and as such Arthur has strengthened further and is about to become the first hurricane of the 2014 Atlantic season.

Atmospheric Outlook for the Forecast Period...Arthur is currently heading northward and will later curve northeastward on the west side of the 1027 to 1032 mb Atlantic subtropical ridge and out ahead of incoming north-central US/SE Canada upper trough/surface 988 mb frontal cyclone. Because the frontal cyclone is far north in relation to the tropical cyclone...the tropical cyclone will soon get caught into a narrowing low-level ridge weakness as the frontal cyclone passes by. However the tropical cyclone is strong/tall enough to be accelerated northeastward through the narrowing low-level weakness by upper-level troughing lingering from the north-central US/SE Canada weather system. Arthur has another 24 hours under the safeguard of an upper ridge that is helping his upper outflow and keeping wind shear low...after which time interaction with the aforementioned upper troughing will increase westerly shear and aid in transition of Arthur into a non-tropical gale.

Thermodynamic Outlook for the Forecast Period...Sea surface temps early in the forecast period will be in the 28 to 30 deg C range...very supportive for additional tropical development. However by late Friday and this weekend...the tropical cyclone will have crossed the 26 deg C isotherm into cooler northwestern Atlantic waters...which will help in the transition of this system to non-tropical. Although Arthur has developed a more symmetric canopy of storms in his currently low shear environment...the canopy has not withstood as I previously expected a batch of dry continental air to the northwest seen in water vapor imagery.

 photo Jul_3_2014_TS_Arthur_Forecast_zpsbda4ee6b.png

Track Forecast...Yesterday's forecasting predicted that Arthur would be just south of or at the 30th parallel by this time...and instead he has tracked a bit faster and is currently just north of the 30th parallel. This means Arthur will be closer to the coast when he intersects the upper trough and bends northeast. Therefore the NHC had adjusted their track forecast further to the left (closer to the coast) since the previous blog update. Computer models have also adjusted to the left and show a considerably faster northeast track since the previous blog update (and therfore the NHC forecast is also showing a faster northeast track). To understand why the models have shifted...I compared the 18Z GFS model run from June 30 against the 18Z GFS model run from June 2. The 18Z model run from June 30 did not display as potent of a tropical cyclone as we currently have. Now that it has been initialized with a strong tropical cyclone for the timeframe we are currently in...it shows Arthur's west side moreso advecting a pocket of cooler air southward...which causes the upper trough to become stronger and more amplified in the most recent model run. In turn this allows Arthur to have a more leftward and faster track on the east side of the stronger/more amplified upper troughing. As such I have also updated my forecast track to be faster and more leftward to play catch up with the recent model runs and updated NHC track. The leftward adjustment in track means Arthur is very likely to strike Nova Scotia and Newfoundland as a strong non-tropical gale during the later part of this upcoming weekend.

Intensity Forecast...I have now discarded the prospect of rapid intensification as I predicted earlier in special update #28A this past afternoon. The dry air has won the battle as mentioned in the above thermodynamic outlook section. Given that Arthur has still not yet intensified into a hurricane...my updated intensity forecast is slightly lowered from my previous one shown in discussion #28. This updated intensity forecast is still a bit higher than the NHC intensity forecast released at 11 PM EDT. The intensity forecast shows weakening by Friday and Saturday as I expect the increasing westerly shear (mentioned at the end of the above atmo outlook section) to begin affecting Arthur. The weakening rate however will not be rapid as Arthur transitions into a vigorous non-tropical remnant low supported by divergence on the east side of upper troughing mentioned at the end of the above atmo outlook.

Impact Forecast...Impact swath is initialized based on the tropical storm wind field depicted in NHC's 11 PM EDT advisory...which is then extrapolated along the forecast track. The impact swath remains narrow as I predict that this system will remain a compact cyclone through the forecast period. With the new track which is more leftward and faster than the previous...the impact swath predicts tropical storm winds reaching all of the North Carolina coast later today (Thursday) thru early Friday...with hurricane conditions possible over the Outer Banks with the center forecast to cross over the Banks. Although the leftward adjustment in track puts the storm closer to New England...all storm force winds are still predicted to pass offshore of New England. By late Saturday...the impact swath shows gale force winds affecting a large section of Nova Scotia. Western Newfoundland could see gale force winds on Sunday.

2014 Atlantic Hurricane Season Birdseye Discussion #28A (Special Update)

By: NCHurricane2009, 7:42 PM GMT on July 02, 2014

...WEDNESDAY JULY 2 2014 3:35 PM EDT...
Tropical Storm Arthur has become a very well organized and compact tropical cyclone with an eye located at 29.5N-79W as the visible satellite image below shows. And given the favorable atmospheric and thermodynamic conditions mentioned in discussion #28...I am forecasting a period of rapid intensification in the short-term especially since Arthur is a compact tropical cyclone and such tropical cyclones are prone to rapid development. My updated intensity forecast is listed below the satellite image.

 photo TSArthur_July2EarlyAfternoon_zps0cdb3c6e.png

8 PM Wednesday July 2...80 mph max sustained wind category 1 hurricane centered offshore of northeastern Florida.

8 PM Thursday July 3...120 mph max sustained wind category 3 hurricane centered offshore of South Carolina.

8 PM Friday July 4...100 mph max sustained wind category 2 hurricane centered just offshore of the North Carolina Outer Banks. If their is a slight westward shift in track...then hurricane conditions could strike the Outer Banks of North Carolina on Friday.

8 PM Saturday July 5...80 mph max sustained wind cyclone offshore of New England transitioning to a non-tropical gale.

2014 Atlantic Hurricane Season Birdseye Discussion #28

By: NCHurricane2009, 5:59 AM GMT on July 02, 2014

...WEDNESDAY JULY 2 2014 2:00 AM EDT...
Tropical depression one located east of Florida and north of the western Bahamas has intensified into Tropical Storm Arthur since my previous blog update. Arthur has also become well organized and is likely to become the first hurricane of the Atlantic season. Visit www.nhc.noaa.gov for the latest government forecasts and information on tropical storm watches/warnings with this system. See special feature section below for my updated assessment of Arthur.

Elsewhere...the tropical wave passing by the Cape Verde Islands in the eastern tropical Atlantic has become less organized as expected while its north half traverses waters below 26 deg C and ingests dry Saharan air to the northwest seen in water vapor satellite imagery.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jul_01_2014_2045Z_zps5d1348f8.png
This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 0123Z-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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jul_01_2014_2045Z_Thermo_zps69218278.png
This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

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

...SPECIAL FEATURE...TROPICAL STORM ARTHUR...
Current prognosis...Tropical depression one has steadily intensified into Tropical Storm Arthur since my previous blog update. As of the 11 PM EDT National Hurricane Center (NHC) advisory...the tropical storm was centered at 27.9N-79.2W. During the previous afternoon and throughout this evening...the tropical storm has become impressive by firing a sizeable rounded area of thunderstorms in its south half...afterwards wrapping some of the activity into its north half. Even more impressive is the recent formation of an eye-type feature. The increase in activity in the north half of the circulation is a sign that northerly wind shear across Arthur has reduced as the eastern US upper ridge (marked by blue H just northwest of Arthur in the above atmo chart) is becoming more stacked with the tropical cyclone...and therefore Arthur has the potential for some impressive stregnthening in the near term.

Atmospheric Outlook for the Forecast Period...As the northwestern Atlantic upper trough has shifted east...the 1022 mb ridge previously north of the tropical cyclone has also shifted east and is merging with 1032 mb Atlantic subtropical ridge. The tropical cyclone is beginning a northward track that will eventually bend to the northeast while it will round the west side of the Atlantic subtropical ridge out ahead of incoming north-central US/southern Canada upper trough/surface 987 mb frontal cyclone. Because the frontal cyclone is far north in relation to the tropical cyclone...the tropical cyclone will later get caught into a narrowing low-level ridge weakness as the frontal cyclone passes by. However the tropical cyclone is expected to be strong/tall enough by that point to be accelerated northeastward through the narrowing low-level weakness by upper-level troughing lingering from the north-central US/southern Canada weather system. Interaction with the upper troughing will increase westerly shear and aid in transition to non-tropical late in the forecast period.

Thermodynamic Outlook for the Forecast Period...Sea surface temps early in the forecast period will be in the 28 to 30 deg C range...very supportive for additional tropical development. However after Friday...the tropical cyclone will cross the 26 deg C isotherm into cooler northwestern Atlantic waters...which will help in the transition of this system to non-tropical. As predicted during special update #27A...the eastern US upper ridge is becoming increasingly stacked overhead of the tropical cyclone...which has reduced the shear such that the thunderstorm activity has become more symmetrical...which in turn has allowed Arthur to fight off surrounding dry air.

 photo Jul_2_2014_TS_Arthur_Forecast_zps9097aeb1.png

Track Forecast...Arthur has not tracked as far west as previously predicted by the NHC and I...and therefore both track forecasts have been shifted a bit to the right. My updated track forecast shown above is a copy-paste of my track forecast from discussion #27A with a rightward adjustment. My Thursday...Friday...and Saturday points remain southwest of the NHC's while the NHC continues to depict a faster northeast track than the reliable GFS and ECMWF (Euro) models show. Therefore my forecast track puts weight on those models.

Intensity Forecast...Given the eye-type feature and anticyclonic outflow/low shear of overhead upper ridge mentioned in the above current prognosis section...and given the favorable thermodynamic parameters mentioned in the above thermodynamic outlook section...Arthur has the potential for brisk or even rapid intensification in the next day or two. Therefore my updated intensity forecast brings Arthur to category 1 hurricane status in 24 hours...and then to a short-lived category 2 status (100 mph max sustained winds) by 48 hours...which is far more bullish than my previous intensity forecast and a bit more bullish than the NHC intensity forecat released at 11 PM EDT. The intensity forecast shows weakening by Friday and Saturday as I expect the increasing westerly shear (mentioned at the end of the above atmo outlook section) to begin affecting Arthur. The weakening rate however will not be rapid as Arthur transitions into a vigorous non-tropical remnant low supported by divergence on the east side of upper troughing mentioned at the end of the above atmo outlook.

Impact Forecast...Impact swath is initialized based on the tropical storm wind field depicted in NHC's 11 PM EDT advisory...which is then extrapolated along the forecast track with some slight growth to account for the fact that Arthur is expected to strengthen. The impact swath remains narrow as I predict that this system will remain a compact cyclone through the forecast period. Impact statement (b) is to reflect the potential for flash flooding in rain squalls outside the impact swath due to the initial slow track of the cyclone. I have removed mention of the Florida peninsula in impact statement (b) as the heavier rain squalls in the last day have been confined to the northwestern Bahamas. Rainfall accumulations on the coastal Carolinas on Thursday and Friday should be limited by a faster and largely offshore storm track. With the rightward adjsutment in the track forecast...the impact swath no longer predicts tropical storm winds reaching the Florida coast...followed by the arrival of tropical storm conditions from Wilmington to Cape Hatteras, North Carolina late Thursday and thru Friday. It should be noted that if Arthur has a slight leftward shift in track for whatever reason...their is a chance that the tight core of hurricane conditions near the center (75+ mph winds) could reach the Outer Banks of North Carolina on Friday.

2014 Atlantic Hurricane Season Birdseye Discussion #27A (Special Update)

By: NCHurricane2009, 6:10 AM GMT on July 01, 2014

...TUESDAY JULY 1 2014 2:10 AM EDT...
Surface low Invest 91-L located east of Florida and north of the western Bahamas has finally intensified into the first tropical depression of the 2014 Atlantic Hurricane Season. Visit www.nhc.noaa.gov for the latest government forecasts and information on tropical storm watches/warnings with this system. This special update is released to show my updated forecast for this system. See special feature section below for updated forecast.

Elsewhere...a tropical wave has rolled off the coast of Africa and currently shows some curved bands of thunderstorms at a location southeast of the Cape Verde Islands. Even though the tropical wave is under a favorable atmosphere beneath a tropical upper ridge...the thermodynamics do not appear favorable with the north half of the system straddling waters below 26 deg C coupled with a swath of dry Saharan air lurking to the northwest as seen in water vapor satellite imagery. In addition computer models do not forecast development from this tropical wave.

...SPECIAL FEATURE...TROPICAL DEPRESSION ONE..
Current prognosis...Invest 91-L has fired an impressive cluster of thunderstorms over and south of the center this evening. Coupled with the fact that aircraft reconnaissance yesterday afternoon found sustained winds of 35 mph...this system has intensified into the first tropical depression of the 2014 Atlantic Hurricane Season. As of the 11 PM EDT National Hurricane Center (NHC) advisory...tropical depression one was centered at 27.6N-79.1W. Activity in the north half of the circulation is currently hampered by northerly wind shear on the east side of the eastern US upper ridge and a patch of dry continental air advected in by these northerlies seen in water vapor imagery.

Atmospheric Outlook for the Forecast Period...Eastern US upper ridge continues to shift east ahead of upper trough and surface frontal cyclone currently pushing in from the north-central US and southern Canada...which is reducing the wind shear and increasing the upper outflow supportive of tropical development as the upper ridge arrives overhead of the tropical depression. The tropical depression is currently trapped between a northern Gulf low-level ridge to the west which has recently merged with 1021 mb ridge to the north supported by convergence on west side of NW Atlantic upper trough...and a 1027 mb subtropical Atlantic ridge to its east. Initial motion of the tropical depression will be southwest and then west as it orbits around the aforementioned 1021 mb ridge. Then as the NW Atlantic upper trough shifts east...the 1021 mb ridge supported by its west side will also shift east/merge with Atlantic subtropical ridge...allowing for a northward and eventual northeastward track of the depression along the west side of the Atlantic subtropical ridge and out ahead of incoming north-central US/southern Canada upper trough/surface frontal cyclone. Because the frontal cyclone is far north in relation to the tropical depression...the depression will later get caught into a narrowing low-level ridge weakness as the frontal cyclone passes by. However the tropical cyclone is expected to be strong/tall enough by that point to be accelerated northeastward through the narrowing low-level weakness by upper-level troughing lingering from the north-central US/southern Canada weather system. Interaction with the upper troughing will increase westerly shear and aid in transition to non-tropical late in the forecast period.

Thermodynamic Outlook for the Forecast Period...Sea surface temps early in the forecast period will be in the 28 to 30 deg C range...very supportive for additional tropical development. However after Friday...the tropical cyclone will cross the 26 deg C isotherm into cooler northwestern Atlantic waters...which will help in the transition of this system to non-tropical. Lastest water vapor imagery shows a patch of dry air being advected in from the north. However as the above atmo outlook mentions...the upper ridge is expected to become stacked overhead of the tropical cyclone...which will reduce the shear such that the thunderstorm activity becomes more symmetrical and fights off the dry air.

 photo Jul_1_2014_TD_One_Forecast_zps34566642.png

Track Forecast...My track forecast shown above is a copy-paste of the track forecast from full discussion #27 with the exception of my forecast points for Thursday July 3 and Friday July 4 which are moved more northeastward to better match the 12Z cycle of yesterday's ECMWF model run and 18Z cycle of the GFS model run...and to be more in agreement with the NHC track forecast which is even faster to the northeast than the aforementioned model runs.

Intensity Forecast...My intensity forecast shown above is a copy-paste of the intensity forecast from full discussion #27 as it is very similar and in good agreement with the NHC intensity forecast. I have added an intensity forecast point for Saturday...which predicts that the system will maintain an elevated strength as it transitions into a vigorous non-tropical remnant low supported by divergence on the east side of upper troughing mentioned at the end of the above atmo outlook.

Impact Forecast...Impact swath shown above assumes that the tropical storm wind field will be compact as I predict that this system will remain a compact cyclone through the forecast period. Impact statement (b) is to reflect the potential for flash flooding in the northwestern Bahamas and Florida peninsula from squalls both within and outside the impact swath due to the initial slow track of the cyclone. On the other hand...rainfall accumulations in the eastern Carolinas on Thursday and Friday should be limited by a faster storm track. The above impact swath predicts low-end tropical storm conditions on coastal Florida from Palm Beach to Cape Canaveral later today and Wednesday...followed by the arrival of tropical storm conditions on the coastal Carolinas late Thursday and thru Friday.

2014 Atlantic Hurricane Season Birdseye Discussion #27

By: NCHurricane2009, 1:17 AM GMT on July 01, 2014

...MONDAY JUNE 30 2014 9:17 PM EDT...
Surface low Invest 91-L located east of Florida and north of the western Bahamas has seen an increase in showers and thunderstorms...and tropical cyclone formation is possible at any time. See special feature section below for additional details which includes an updated forecast on 91-L. I will release a special update if tropical cyclone formation occurs before my next full blog update tomorrow evening.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jun_30_2014_2045Z_zpsbfef03b1.png
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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jun_30_2014_2045Z_Thermo_zps9b376a07.png
This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

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

...SPECIAL FEATURE...SURFACE LOW INVEST 91-L...
Current prognosis...Invest 91-L continues on a slow southwestward track while orbiting around a low-level ridge in the northeastern Gulf of Mexico (red zig-zag line and 1019 mb center marked to the left of 91-L in the above atmo chart). Afternoon visible satellite animation suggests the center is currently at 28N-79W. Shower and thunderstorm activity has increased since the previous update early this morning and therefore tropical cyclone formation is possible at any time. However the increased activity remains confined to the south half of the circulation due to northerly wind shear on the east side of the eastern US upper ridge (marked by blue H to the north of 91-L in the above atmo chart).

Atmospheric Outlook for the Forecast Period...Eastern US upper ridge continues to shift east ahead of upper trough and surface 982 mb frontal cyclone currently pushing in from the north-central US and southern Canada...which is reducing the wind shear and increasing the upper outflow supportive of tropical development as the upper ridge arrives overhead of Invest 91-L. 91-L is currently trapped between 1019 mb northeastern Gulf ridge to its west which has recently merged with 1021 mb ridge to the north supported by convergence on west side of NW Atlantic upper trough...and a 1027 mb subtropical Atlantic ridge to its east. Initial motion of 91-L will be southwest and then west as it orbits around the aforementioned 1019/1021 mb ridge. Then as the NW Atlantic upper trough shifts east...the 1021 mb ridge supported by its west side will also shift east/merge with Atlantic subtropical ridge...allowing for a northward and eventual northeastward track for 91-L along the west side of the Atlantic subtropical ridge and out ahead of incoming north-central US/southern Canada upper trough and surface 982 mb frontal cyclone. With 91-L being currently far south in relation to the north-central US/southern Canada weather system...it seems their is potential for 91-L to later on get left behind by the low-level ridge weakness associated with the weather system. However their have been computer model solutions such as the Euro (ECMWF) that for the last few runs show 91-L becoming a strong/tall enough tropical cyclone such that upper-level troughing associated with the weather system will be able to pull 91-L through a narrowing low-level weakness and out to sea.

Thermodynamic Outlook for the Forecast Period...Sea surface temps in the environment of Invest 91-L are in the 28 to 30 deg C range...very supportive for tropical cyclone formation. Lastest water vapor imagery shows that deep-layered ridging (1019 mb center and blue H near 91-L in the above atmo chart) have advected in some continental dry air into the north half of 91-L's circulation. However as the above atmo outlook mentions...the upper ridge is expected to become stacked overhead of 91-L...which will reduce the shear such that 91-L's thunderstorm activity should become more symmetrical and fight off the dry air.

24 Hr Forecast (1800Z July 1)...40 mph max sustained wind tropical storm centered at 27.2N-80W just offshore of Florida. Still expecting system to be under northerly shear but becoming better organized as the shear reduces. Forecasting additional southern and western squalls to continue firing up over the Florida peninsula and northwestern Bahamas.

48 Hr Forecast (1800Z July 2)...50 mph max sustained wind tropical storm centered at 29N-80.2W. Expecting system to be better organized and more symmetrical as it aligns with anticyclonic center of upper ridge. Forecasting western squalls over Florida Peninsula and coastal Georgia.

72 Hr Forecast (1800Z July 3)...65 mph max sustained wind tropical storm centered at 31N-80W. Forecasting western squalls over northeastern Florida...coastal Georgia...and southern South Carolina.

96 Hr Forecast (1800Z July 4)...65 mph max sustained wind tropical storm centered near Cape Fear North Carolina at 34N-77.5W on an accelerating northeastward track. This is further northeast and faster than my previous forecasts for July 4th to become more lined up with model solutions that suggest this system being strong/tall enough to be accelerated northeastward through a narrowing low-level ridge weakness by upper troughing as discussed at the end of the above atmo outlook. This also means a system under increasing westerly shear caused by the upper trough and a system transitioning to a non-tropical cyclone supported by divergence on the east side of the upper troughing beyond this forecast point. Forecasting squalls to only cover far eastern North Carolina during this timeframe due to the increasing westerly shear.


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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