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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 #4

Updated: May 30

*******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.*********


...TUESDAY MAY 28 2024 11:40 PM EDT...

Even though the 2024 Atlantic Hurricane Season does not officially start until June 1... resuming daily birdseye view posts on the Atlantic tropics while tracking a developing disturbance in the southern Caribbean Sea... see area of interest #3 section below for more information.


Elsewhere... an unusually robust surface tropical wave of low pressure for late May emerged from western Africa within the last few days and is currently in the eastern Atlantic... in the vicinity of 7.5N-27.5W. Further development of this feature is not expected due to lurking dry Saharan air to the northwest and as the currenlty amplifying northwest Atlantic upper ridge pushes the shearing southwestern portion of the current central Atlantic upper trough southeastward into the region. In the long range the shearing upper trough fragment weakens in the model guidance while remaining cut-off from high-latitude cold air... therefore barring dry Saharan air intrusions and ongoing robust tropical waves emerging from Africa we may have to watch for unusually early tropical development in the eastern or central tropical Atlantic as we move into June.


AREA OF INTEREST #3... A surface tropical wave of low pressure continues advancing westward across the central Caribbean Sea. Just ahead of (west of) the wave... a small upper anticyclone has developed near 11N-80W in the wake of an upper trough that has recently collapsed. Outflow is robust on the north side of the anticyclone due to an upper wind channel that extends several hundred miles east-northeast into the south side of the current central Atlantic upper trough. The robust outflow of the anticyclone has resulted in equally robust pulsing thunderstorm activity that has persisted all day. More recently cyclonic turning... probably a forming mid-level tropical low pressure... has developed on colorized infrared satellite loops near 11N-81W. Through 0140Z tonight the most recent pulse of activity is near (just east of) the mid-level low pressure spin which will likely re-enforce it. The central Caribbean surface tropical wave of low pressure approaching from the east will soon align with the mid-level low pressure spin... and I assess a tropical disturabnce has a good probability of materializing. This will mark the third tropical Atlantic area of interest I have tracked on this site this year.


Anything that develops in this region is likely to move slowly due to the surface ridge weakness associated with the frontal system that is about to depart eastern North America. However as the surface ridge currently just southwest of Canada's Hudson Bay encroaches into the region... a slow westward progress toward southeastern Nicaragua is likely and I currently do not expect this system to stay in the offshore southern Caribbean waters for more than 48 hours. Currently the GFS model is the only model that hints at tropical development during this period of time... assigning a low 20% chance of tropical cyclone formation for this area of interest at present. Regardless of further development or not... increased rainfall with flash flooding potential is possible for Costa Rica and Nicaragua over the next couple of days.


In the longer-term... the remnants of this disturbance may accelerate northeast and re-emerge over Caribbean waters... then move across the northern Caribbean Islands and into the western Atlantic while transitioning into a system supported by the eastern divergence zone of an upper trough that arrives from the southeastern US in 120+ hours (this upper trough will be the southern fracture of the current trough offshore of California). At this time the traditionally reliable model guidance suggests the upper trough will be too low in amplitude (apply excess westerly wind shear) such that long-range tropical development would be unlikely in this scenario (only the less reliable NAVGEM model suggests otherwise).

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

IOH 24 Hr Outlook (0000Z May 30)... 20% chance of tropical cyclone formation (offshore of southeastern Nicaragua and Costa Rica near 11.5N-81.5W)

IOH 48 Hr Outlook (0000Z May 31)... 20% chance of tropical cyclone formation (just offshore of southeastern Nicaragua near 11.5N-83.8W)

IOH 72 Hr Outlook (0000Z Jun 1)... 0% chance of tropical cyclone formation (southeastern Nicaragua near 11.5N-84.5w)

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

Not in the official outlook


...COMPUTER MODEL SUMMARY...

Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).


1200Z (May 28) CMC Model Run...

**For area of interest #3... no development shown


1200Z (May 28) ECMWF Model Run...

**For area of interest #3... no development shown


1800Z (May 28) GFS Model Run...

**For area of interest #3... small tropical low develops just offshore of Costa Rica and just north of 10N latitude at 42 hours which drifts northwest into northeast Nicaragua coast at 96 hours... while interacting with divergence zone of upper trough that ejects from southeastern US the disturbance evolves into a broad surface trough extending northeast across Jamaica... eastern Cuba... and southeastern Bahamas through 144 hours (western Atlantic surface low develops east of this disturbance and near 24.5N-64.5W by 168 hours... however westerly shear imparted by upper trough likely excessive for tropical development here)


1800Z (May 28) NAVGEM Model Run...

**For area of interest #3... broad tropical low develops just west-southwest of Jamaica through 108 hours... broad tropical low gradually intensifies while moving northeast across Cuba through 144 hours and possible broad tropical cyclone over northwestern Bahamas through 168 hours.

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