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Potential Tropical Cyclone Four Discussion Number   3
NWS National Hurricane Center Miami FL       AL042022
400 AM CDT Sat Aug 20 2022
 
We have a much better view of the low clouds on the western side 
of the disturbance in proxy-visible satellite imagery than we did 
last evening when they were obscured by high-level cirrus, and the 
low clouds' south-to-north motion just off the coast of Mexico 
suggests that the disturbance still does not have a closed surface 
circulation.  However, a mid-level circulation remains evident and 
is the focus of a recent resurgence in deep convection.  It is 
assumed that the maximum winds in the system are still 30 kt, but 
an Air Force Reserve reconnaissance flight scheduled for later this 
morning should give us a better idea of the disturbance's structure 
and intensity.

The disturbance continues to move northwestward at 12 kt, and model 
guidance is in fairly good agreement that a steady northwestward or 
north-northwestward motion should continue for the next 24 hours or 
so.  This trajectory should bring the system inland near or just 
south of the mouth of the Rio Grande late this afternoon or evening, 
which is the same scenario that has been indicated in previous 
advisories.

There remains uncertainty if the disturbance will be able to 
develop a closed surface circulation--and become a tropical 
cyclone--before it reaches the coast later today.  At best, the 
global models are resolving a well-defined vorticity maximum at 
about 5000 ft above the surface and perhaps a surface trough near 
the coast of Mexico, but none of them explicitly show the 
development of a well-defined surface circulation.  As long as deep 
convection continues, however, it could spur the development of a 
surface center before reaching the coast.  That said, the new NHC 
forecast now only shows the system reaching a peak intensity of 35 
kt, which is still above all of the guidance.  A remnant low 
position is provided at 36 hours for continuity, but it's more 
likely that the system will have dissipated by then--if it even 
forms at all.
 
 
KEY MESSAGES:
 
1. Tropical storm conditions are expected across portions of
northeastern Mexico and southern Texas this afternoon and evening, 
where a Tropical Storm Warning is in effect.
 
2. Rains from the disturbance may begin to affect the eastern coast 
of Mexico, from northern Veracruz across parts of Tamaulipas and 
Nuevo Leon, today.  This rainfall may produce flash flooding.  
Heavy rain may also move to the far south Texas coast through Sunday 
morning, producing local flash, urban, and small stream flood 
impacts.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/0900Z 22.8N  95.8W   30 KT  35 MPH...POTENTIAL TROP CYCLONE
 12H  20/1800Z 24.4N  96.9W   35 KT  40 MPH...TROPICAL CYCLONE
 24H  21/0600Z 26.3N  98.3W   30 KT  35 MPH...INLAND
 36H  21/1800Z 27.5N  99.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  22/0600Z...DISSIPATED
 
$$
Forecaster Berg
 
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