*******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.*********
...SUNDAY JULY 21 2024 3:40 PM EDT...
Tropical activity in the Atlantic basin remains calm due to higher concentrations of dry Saharan air toward the east and pockets of suppressing cut-off upper vorticity across the western half of the basin. Through the next week the western cut-off upper vorticity is expected to generally decay due to prolonged isolation from high-latitude cold air... allowing for the ongoing eastern Atlantic tropical upper ridging to expand westward into the eastern Caribbean. In addition the warm surface southerly flow ahead of the next slow-moving frontal system that will develop over central North America... followed by the next frontal system that moves into western North America... will promote warm core upper ridging across the Gulf of Mexico and southeastern United States... with whatever remaining of the decaying upper vorticity lingering across the western and central Caribbean while sandwiched between the Gulf of Mexico and eastern Caribbean upper ridging. Therefore for the next few days expecting the following:
For the western and central Caribbean... no tropical cyclone formation expected as suppressing upper vorticity lingers in the region.
For the eastern Caribbean and tropical belt of the Atlantic basin (Lesser Antilles to western Africa)... despite upper ridging favoring tropical activity the models continue to not show tropical development perhaps while projecting that dry Saharan air will continue to blanket the region.
For the western Gulf of Mexico... including coastal northern Veracruz... coastal Tamaulipas... and coastal Texas... a tropical disturbance is possible within the next few days. In the upper-levels... the cut-off upper vortex near coastal Tamaulipas will soon be merging with the latest upper trough that is now settling into central North America. The upper trough that results from the merger will likely be amplified enough to promote lower wind shear and supportive upper divergence over the western Gulf of Mexico. Anticyclonic outflow on the west side of the forecast Gulf of Mexico upper ridging mentioned in the first paragraph of this post may also promote tropical activity in the western Gulf. Currently divergence ahead of the coastal Tamaulipas upper vortex has interacted with surface convergence on the north side of the tropical wave that has recently passed over southeastern and south-central Mexico to produce thunderstorms across the western Gulf of Mexico... however 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 maximum low-level spin is over southeastern Mexico (Isthmus of Tehuantepec) instead of over water and therefore I have not declared a tropical area of interest at this time. The next tropical wave that will move over the southwestern Gulf of Mexico is currently in the Caribbean just west of Jamaica... if this wave later deposits a low-level spin enhanced by the aforementioned upper-level wind pattern in the western Gulf of Mexico... or alternatively if a low-level spin is simply generated by the upper-level wind pattern... will declare a tropical area of interest for the western Gulf in future updates.
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).
0000Z (Jul 21) CMC Model Run...
**No tropical development shown in Atlantic basin through 168 hours (7 days)
0000Z (Jul 21) ECMWF Model Run...
**No tropical development shown in Atlantic basin through 168 hours (7 days)
0600Z (Jul 21) GFS Model Run...
**No tropical development shown in Atlantic basin through 168 hours (7 days)
0600Z (Jul 21) NAVGEM Model Run...
**North end of current Caribbean tropical wave (just west of Jamaica) evolves into a tropical low just south of the Texas/Mexico border at 78 hours which dissipates shorlty thereafter while drifting northwestward ashore
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