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BIRDSEYE VIEW POSTS

Since 2012 on the now retired Weather Underground blogs, I have been posting annotated "birdseye view" charts of the Atlantic basin, with a detailed explanation and forecasting that references the chart. From there you may know me as "NCHurricane2009." While I now do these "birdseye view" posts here, I will continue to do comments at Yale Climate Connections via Disqus where the former Weather Underground community has moved to. Feel free to reply to me there, at my Disqus feed at this link, or via e-mail at IOHurricanes@outlook.com 

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MY 2024 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #88B (Special Update)

Updated: Sep 25

*******Note that forecast and outlooks in this post are NOT the official forecast from the National Hurricane Center (NHC). They are my own detailed views on the Atlantic tropics based on current observations and latest computer model runs. As such do not make decisions based on my posts...consult news media...watches and warnings from your local weather office...and any evacuation orders issued by local governments to make the most informed and best decisions. Visit the NHC website hurricanes.gov (hurricanes dot gov) for the latest watches/warnings and official forecasts on active tropical cyclones.*********


…UPDATE…WEDNESDAY SEPTEMBER 25 2024 6:43 AM EDT...

Satellite image of Tropical Storm Helene as it moves into the northeastern Yucatan peninsula… image taken at 1026Z:

Since being upgraded to a named storm… Helene has gradually strengthened and has 65 mph maximum sustained winds as of the writing… and the center has largely tracked west and is now near the northeastern Yucatan peninsula. The west turn is likely due to the center being steered by the remainder southern part of the broad low pressure area from which Helene formed within. Interests in the northeastern Yucatan should be sheltered in place as heavy rainfall… stronger coastal surf… and tropical storm to hurricane force winds are upon the area. The long-term forecast has also shifted west… shifting the potential for the worst hurricane-force impacts (wind and coastal storm surge) into the eastern Florida panhandle in addition to the northwest Florida peninsula for early Friday.


...UPDATE...TUESDAY SEPTEMBER 24 2024 11:20 AM EDT...

The western Caribbean disturbance tagged as area of interest #30 in this blog post (potential tropical cyclone nine) has recently been upgraded to Tropical Storm Helene with 45 mph maximum sustained winds after a stronger well-defined surface low pressure center was spotted by aircraft recon and very recent visible satellite frames. The well-defined center is a little northwest of my previous forecast track presented below... increasing the prospects of coastal surf for the northeastern Yucatan peninsula within the next 24 hours.


...TUESDAY SEPTEMBER 24 2024 10:20 AM EDT...

The following are special updates on current areas of interest in the Atlantic basin while on vacation. I completed the forecasts for area of interest #30 through #32 while traveling back home around 0000Z early today... however the situation for each area of interest has not changed since then. Note area of interest #30 is expected to bring impacts to the Cayman Islands… western Cuba… Florida… and much of the southeastern United States over the next four days… see area of interest #30 section for more details.


Satellite image of the Atlantic basin as of 0730Z… current areas of interest are highlighted:

Surface chart of the Atlantic basin as of 0000Z… current areas of interest are highlighted:


Upper air chart of the Atlantic basin as of 0000Z… current areas of interest are highlighted:


AREA OF INTEREST #30 (POTENTIAL TROPICAL CYCLONE NINE)... The western Caribbean tropical disturbance that was expected to materialize in an expanding upper anticyclone… in between Yucatan and western Atlantic upper vorticity lobes moving away from each other… has done so but at a notably further northeast position than previously forecast… therefore the future track of this disturbance has been notably shifted east. The Yucatan upper vorticity is still blocking the western outflow of this disturbance… however the spin has become defined enough along with enough organization in the eastern thunderstorm squalls for the NHC to issue potential tropical cyclone advisories in anticipation this system will become a tropical cyclone soon… in order to get tropical cyclone watches/warnings out early for land areas in the forecast path of this system. I have also switched to a specific track and intensity forecast projection due to the progress this disturbance has made toward becoming a tropical cyclone.


During the forecast period… the upper vorticity over the Yucatan merges with the upper trough and associated surface frontal low that will soon be moving into the Great Lakes region of North America. The initial forecast track starts north-northwest around the current narrow US east coast surface ridge (supported by the eastern convergence zone of the current SE US upper ridge wave)… followed by a north turn across western Cuba then north-northeast acceleration into the northwestern Florida peninsula ahead of the lengthy upper trough. After landfall with Florida… the south part of the upper trough is forecast to become a cut-off upper vortex to the east of an amplified upper ridge… with this system arcing north then eventually north-northwest around the east side of the upper vortex… a path that takes the inland remnant system across the eastern US. Regarding intensity… over the next 24 hours I forecast this system to develop a better defined and stronger surface low pressure center to be upgraded to a tropical storm… then begin brisk intensification into a category 1 hurricane between 24 and 48 hours. After that time southwesterly shear associated with the incoming lengthy upper trough may hamper development… so my peak intensity forecast at this time (at 72 hours) calls for no higher than a top-end category 1 hurricane. By 96 hours I expect this system to transition into a southeast US remnant frontal low supported by the eastern divergence zone of the upper vortex… with the divergence zone slowing the decay rate of the inland remnant circulation.


Regarding impact to land areas:

(1) For the Cayman Islands… expect periods heavy rainfall to continue through Thursday morning.

(2) For western Cuba… expect a sustained period of heavy rain to develop later today… lasting through mid-Thursday… likely resulting in rainfall flooding. Tropical storm to hurricane force winds and coastal surf are expected late tomorrow through early Thursday… complete preparations by tomorrow afternoon.

(3) For the Florida Keys… expect a sustained period of heavy rain to develop late today… lasting through late Thursday… likely resulting in rainfall flooding. Tropical storm force winds and coastal surf are possible on Thursday.

(4) The southwest Florida peninsula coast will be subject to coastal surf on Thursday. For the remainder of the Florida peninsula west coast and panhandle… coastal surf arrives by late Thursday and early Friday… becoming severe for the for the northwest Florida peninsula on early Friday. Hurricane to tropical storm force winds are expected to spread onshore across the northern half of the Florida peninsula and southern Georgia early Friday… with the most severe wind toward the northwest Florida peninsula coast. Heavy rainfall with flooding potential is expected to spread across central and northern Florida… then across much of the southeast US from Friday through Saturday. Due to the slowed inland decay rate mentioned at the end of the prior paragraph… gusty winds are also possible across much of the southeast US through Saturday.

******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********

0 Hr Position (0000Z Sep 24)… 35 mph maximum sustained wind tropical low centered southwest of the Cayman Islands at 18.1N-82.2W

IOH 24 Hr Forecast (0000Z Sep 25)... 45 mph maximum sustained wind tropical storm centered south of the Isle of Youth of western Cuba and west of the Cayman Islands at 19.5N-83W

IOH 48 Hr Forecast (0000Z Sep 26)… 85 mph maximum sustained wind hurricane centered on the north coast of Cuba’s west tip at 22.8N-84W

IOH 72 Hr Forecast (0000Z Sep 27)… 95 mph maximum sustained wind hurricane centered just offshore of the northwest Florida peninsula coast at 28.5N-83.5W

IOH 96 Hr Forecast (0000Z Sep 28)… Gale-force remnant frontal low centered over the western NC/SC border at 35N-82.5W

*****National Hurricane Center (hurricanes.gov) official outlook as of 8 AM EDT*************************

Formation chance through 48 hours... 100%

Formation chance through 7 days... 100%

*****National Hurricane Center (hurricanes.gov) official forecast as of 5 AM EDT*************************

Peak Strength (1800Z Sep 26)… 115 mph maximum sustained wind major hurricane centered in the northeastern Gulf of Mexico at 27.8N-84.4W

4-Day Position (0600Z Sep 28)… 15 mph maximum sustained wind dissipating remnant low centered over the Indiana/Kentucky border at 38.5N-85.5W


AREA OF INTEREST #31... The central Atlantic surface low that has been climbing northward along 55W longitude is already in the process of becoming absorbed by the large-scale approaching western Atlantic frontal low... hence while finally losing its thunderstorm mass in recent hours its tropical development is no longer possible and this is my final statement on this feature on this blog (it was also removed from the NHC outlook over the latter part of the weekend)


AREA OF INTEREST #32... The tropical wave of low pressure that exited Western Africa over the weekend has recently proceeded to develop a circular core of thunderstorms while passing by the southern Republic of Cabo Verde Islands… despite regional dry Saharan air. This morning’s true color visible satellite shows beige-tint dry Saharan air lies off to the northeast with none in the future path of the wave… computer model support showing development is high… and a regional tropical upper ridge axis featuring low shear and upper outflow remains in place. Therefore assigning a high 90% chance of tropical cyclone formation for the next three days as the tropical wave continues west while steered by the eastern Atlantic surface layer of the regional mid-latitude deep layer ridge. After that time the current upper trough moving toward the Great Lakes region of North America merges with the current western Atlantic upper vorticity to a make large scale upper trough that begins to turn this system north into the open central Atlantic. Light southwesterly shear imparted by the flow ahead the upper trough may begin to affect this system in the 3 to 5 day window… thus I lower development odds to 70% for that timeframe.

******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********

Formation chance through 3 days... 90% (eastern tropical Atlantic near 15N-38W)

Formation chance days 3 to 5... 70% (central Atlantic near 23N-43W)

*****National Hurricane Center (hurricanes.gov) official outlook as of 8 AM EDT*************************

Formation chance through 48 hours... 40%

Formation chance through 7 days... 80%

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