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Potential Tropical Cyclone Nine Discussion Number   1
NWS National Hurricane Center Miami FL       AL092023
1000 AM CDT Mon Aug 21 2023

The broad area of low pressure over the central Gulf of Mexico 
continues to gradually become better organized with showers and 
thunderstorms increasing on the system's north side.  However, 
surface observations and early morning visible satellite images 
suggest that it does not have a well-defined center yet, and 
therefore, does not meet the definition of a tropical cyclone at 
this time.  Since the system is forecast to strengthen and make 
landfall as a tropical storm on Tuesday, advisories are being 
initiated on Potential Tropical Cyclone Nine with Tropical Storm 
Warnings now in effect for portions of south Texas.

The disturbance is moving fairly quickly to the west at 14 kt on the 
south side of a strong mid-level ridge located over the central U.S. 
An even faster motion to the west or west-northwest is expected, 
taking the system over southern Texas by midday Tuesday.  It should 
be noted that since the system does not yet have a clear center, the 
details of the track forecast are a bit uncertain.  The Air Force 
Hurricane Hunters are scheduled to investigate the system this 
afternoon, which should help assess the low-level structure.

The environmental factors are generally favorable for the system to 
strengthen. However, there is limited time for the disturbance to 
take advantage of those conditions, especially since it still lacks 
a well-defined center.  The NHC official intensity forecast shows 
the system reaching a peak intensity of 40 kt before landfall, which 
is near the high end of the model guidance.  Rapid weakening is 
expected after landfall.

KEY MESSAGES:

1. Heavy rainfall from Potential Tropical Cyclone Nine is expected 
across South Texas on Tuesday and Wednesday. The heavy rainfall may 
produce areas of flash and urban flooding. Across portions of 
Coahilla and Nuevo Leon in Mexico, flash flooding with possible 
landslides in mountainous terrain is expected Tuesday into 
Wednesday.

2. Coastal flooding is possible along the south Texas coast 
tonight through Tuesday morning.  

3. Tropical storm conditions are expected in the warning area and 
are possible in the watch area beginning Tuesday morning.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/1500Z 25.0N  89.9W   25 KT  30 MPH...POTENTIAL TROP CYCLONE
 12H  22/0000Z 25.5N  92.8W   30 KT  35 MPH...TROPICAL CYCLONE
 24H  22/1200Z 26.6N  96.8W   40 KT  45 MPH
 36H  23/0000Z 27.8N 100.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  23/1200Z...DISSIPATED
 
$$
Forecaster Cangialosi
 
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