MY 2022 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #11A (Special Update)
*******Note that forecasts 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 MAY 22 2022 6:54 PM EDT...
Satellite image of newly-formed Gulf of Mexico tropical disturbance taken at 2241Z. Red arrow points to possible location of surface spin formation:
As of 2 PM EDT… the National Hurricane Center (NHC) in their tropical weather outlook product began issuing tropical cyclone formation probabilities for a new disturbance located in the northeastern Gulf of Mexico. The NHC assigned odds of tropical cyclone formation are 10% as of this writing.
The following technical information explains the formation of this disturbance:
(1) A divergence zone of a cold core upper trough over the southeastern US was producing thunderstorm activity over parts of the southeast US coast by Friday evening.
(2) A warm core deep-layer ridge has been taking shape over the western Atlantic due to warm surface southerly flow ahead of an eastern Canada frontal cyclone… followed by a similar southerly flow ahead of the latest cold front sweeping across the eastern US. The expansion of this ridge has caused the southeast US upper trough and associated thunderstorms to retrograde west-southwest into the northeastern Gulf of Mexico as of Saturday.
(3) As of Sunday (today)… wind shear over the northeastern Gulf of Mexico has relaxed due to the ongoing expansion of the deep-layer ridge as well as the weakening of the cold core southeast US upper trough… which has been isolated from high-latitude cold air. The upper flow has become more anticyclonic and supportive of thunderstorm upper outflow needed for tropical development due to the encroachment of the expanding deep-layer ridge.
(4) CIMSS 850 mb vorticity (http://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=) shows an elongated area of mid-level low pressure rotation offshore of southeastern Louisiana
(5) ASCAT satellite scans of surface winds (https://manati.star.nesdis.noaa.gov/datasets/ASCATBData.php) missed the bulk of this disturbance… a surface low pressure spin (needed for tropical cyclone status) is not detected as of this writing. ASCAT suggested winds in the environment of this disturbance are no higher than tropical depression force… therefore any tropical cyclone that forms will likely be on the weak side wind-wise.
Regarding impact to land areas:
(1) The disturbance is being steered northward toward the US Gulf coast (Alabama… Mississippi… western Florida panhandle) by the western Atlantic deep-layer ridge… and will move ashore within the next 24 hours
(2) Regardless of whether the disturbance becomes a weak tropical cyclone (for example tropical depression or minimal tropical storm) or stays as is… expect locally heavy rains with flash flooding potential across southeastern Louisiana… southeastern Mississippi… southern Alabama… and western Florida panhandle through tonight. Gusts are possible from any stronger thunderstorms.
For more information on the rest of the Atlantic tropics… refer to full update #11 on the home page of this site.