MY 2024 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #9

*******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 JUNE 4 2024 9:56 AM EDT...

For the western Atlantic... as forecast over the last few days the upper trough that was over the southeastern United States has moved offshore into the western Atlantic. The divergence zone of the trough is supporting thunderstorm activity north of the Caribbean Islands... with the most concentrated activity toward the west and offshore of the southeastern Bahamas as of this writing. Surface convergence provided by the tail end of the surface front attached to the ongoing northwest Atlantic deep-layer low is also adding to this activity. However not declaring a tropical area of interest in this region as the CIMSS 850 mb vorticity product (https://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=vor&zoom=&time=) shows the strongest low-level rotation is northeast of the most concentrated thunderstorm activity... and this rotation is forecast by the models to become a typical non-tropical frontal low supported by the divergence zone of the aforementioned upper trough. As the upper trough remains low in amplitude while continuing to swing east... it will also impart hostile westerly vertical shear unfavorable for tropical development in this region.

For the eastern and central tropical Atlantic... noting regional westerly wind shear is beginning to relax as the central Atlantic upper trough begins weakening from its prolonged isolation from high-latitude cold air. However the recent tropical wave that was unseasonably vigorous while in the far eastern tropical Atlantic has since succumbed to dry Saharan air while now at 25W longitude... and there are currently no other unseasonably vigorous wave in this region to take advantage of the relaxing shear.

For the Yucatan peninsula and adjacent southern Gulf of Mexico and western Caribbean waters... surface tropical waves currently at 72W longitude and 55W longitude will continue their typical westward progression and move into this region in the days ahead. Upper-level wind forecasts show the current central US upper trough and southern portion of the current western North America upper trough will also sag southeastward into this region and under the force of a warm core upper ridge that becomes established across the southern US due to forecast vigorous northeastern Pacific frontal systems pumping in warm air. The divergence zone of the southeastward-sagging upper-level energy may interact with the aforementioned surface tropical waves to produce a tropical disturbance in the Yucatan region... an idea most championed by recent CMC and GFS model runs. However their is some uncertainty as to whether or not tropical development would occur with this disturbance as the forecast configuration of the upper-level energy is not settled yet... thus the amount of wind shear unfavorable to tropical development that would be imparted by the energy is not yet clear. Therefore not declaring a tropical area of interest for this situation at this time.

...COMPUTER MODEL SUMMARY...

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

0000Z (Jun 4) CMC Model Run...

**Caribbean tropical wave currently at 72W longitude evolves into north-south elongated tropical low just offshore of the Yucatan peninsula east coast at 126 hours... the tropical low subsequently lifts north-northeast toward the southwest Florida coast through 168 hours while chasing surface ridge weakness associated with large frontal system that moves from western to eastern North America during the forecast period.

0000Z (Jun 4) ECMWF Model Run...

**No tropical development in the Atlantic basin thru 168 hours (7 days)

0000Z (Jun 4) GFS Model Run...

**Tropical waves currently at 72W longitude and 55W longitude merge into broad tropical low centered over northeastern Yucatan peninsula by 153 hours... the tropical low begins turning northeast toward the western tip of Cuba through 168 hours while chasing surface ridge weakness associated with large frontal system that moves from western to eastern North America during the forecast period.

0000Z (Jun 4) NAVGEM Model Run...

**In longer range south fragment of current western North America upper trough ejects offshore into the western Atlantic... divergence zone of this fragment produces surface trough southeast of Bermuda at 114 hours... upper trough fragment subsequently lifts out to northeast which leaves the surface trough to drift south while trapped in deep-layer ridging... the southward-drifting feature evolves into a tropical low near 24.5N-56W by 168 hours