*******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.**********
...FRIDAY AUGUST 19 2022 6:20 PM EDT...
The following is a special update on the tropical disturbance whose center of rotation has spent today moving west-northwest across the Bay of Campeche... tagged as area of interest #19 in full update #78 last evening. See full update #78 on the home page for more information on the rest of the Atlantic tropics.
AREA OF INTEREST #19 (POTENTIAL TROPICAL CYCLONE FOUR)...Satellite image of tropical disturbance currently moving across the Bay of Campeche...taken at 2021Z:
The tropical disturbance whose center of rotation was previously over the Mexican province of Campeche has spent much of today moving west-northwest across the warm waters of the Bay of Campeche. As it did so... well-organized thunderstorm activity redeveloped as of this morning and has persisted till now. As shown by the CIMSS 850 mb vorticity product much of the low-level spin in the region has been to the south of the thunderstorm mass instead of underneath it (http://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=). However 850 mb vorticity has been increasing over the Bay of Campeche and beneath the southern reaches of the thunderstorm mass. The ASCAT-C descending pass has a similar story...suggesting a surface trough of low pressure extending northward into the thunderstorm mass rather than a closed surface spin beneath the mass. Aicraft reconaissance has also confirmed the lack of a fully closed surface spin... however maximum sustained winds have increased to 35 mph. The National Hurricane Center has assessed that this disturbance has a high chance of becoming a tropical storm within the next 24 hours as it closes in on Tamaulipas and far southern Texas... and as of 5 PM EDT (4 PM CDT) has classified the disturbance as Potential Tropical Cyclone Four in order to issue tropical storm warnings for these land areas.
Regarding the intensity forecast: Going for this disturbance is the overhead upper anticyclonic ridge featuring upper outflow...warm water temperatures... and organized thunderstorm mass which is increasingly developing banding features and vibrant cirrus outflow clouds. Going against the disturbance is that has yet to develop a fully closed surface spin... and there is still some residual upper vorticity just to the west that is keeping the heaviest thunderstorms leaned toward the east side of the area of surface vorticity/lowest surface pressures. Weighing both the positive and negative factors... I forecast peak strength to reach moderate tropical storm status (50 mph max sustained winds) instead of a strong tropical storm. As of the 4 PM CDT advisory the NHC has the same idea while projecting a peak strength of 45 mph maximum sustained winds. Note for 48 hours that even though the center of circulation is expected to be over land... I still forecast tropical depression status as the largely north angle in track will keep the center close enough to the Texas/Mexico coast such that offshore thunderstorm bands may still feed this system and keep it from weakening rapidly. At 72 hours the system as a whole should be tucked away further inland... and this is when I project remnant low status.
Regarding the track forecast...the previous one has performed spot on and so no changes are made in this update. The disturbance's current west-northwest track is expected to bend increasingly north while the disturbance rounds the south and west sides of the Gulf of Mexico surface ridge... eventually heading toward a surface ridge weakness currently being induced by the central US frontal system. By 72 hours the inland track of this system may lean more westward as the central US frontal system departs eastward... with a surface ridge building in its wake and to the north of this system.
Regarding impacts to land areas...interests in Tamaulipas and southern Texas to the south of Matagorda Bay should now be preparing for tropical storm conditions likely to arrive tomorrow afternoon or evening. Expect heavy rainfall with flash flooding potential on both inland and coastal areas... with gusty winds and ocean swells along the coast. Although chances for tropical storm winds and gusts are lower on the southern Texas coast with the center expected to track inland... as noted in the above intensity forecast discussion this system could be initially slow to weaken post-landfall due to the center still being near the coast. Tropical storm winds and gusts on the southern Texas coast would also be more likely should this system strengthen a little more than currently forecast.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (1800Z Aug 19)...Tropical low centered in the Bay of Campeche at 20.7N-94.5W
IOH 24 Hr Forecast (1800Z Aug 20)...50 mph maximum sustained wind tropical storm centered just offshore of Tamaulipas near 23.8N-97.5W
IOH 48 Hr Forecast (1800Z Aug 21)...35 mph maximum sustained wind tropical depression centered inland over the Texas/Mexico border at 26.1N-98W
IOH 72 Hr Forecast (1800Z Aug 22)...Remnant low centered inland over southern Texas at 29N-99.5W