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Tropical Storm Katia Discussion Number   4
NWS National Hurricane Center Miami FL       AL122023
800 AM CVT Sat Sep 02 2023
 
The depression has become better organized overnight.  Cloud tops
temperatures have decreased to -76 Celsius over the surface center
and curved banding has improved, mainly over the northern
semi-circle.  UW-CIMSS AiDT and DPRINT objective satellite 
intensity estimates, as well as the Dvorak estimated from TAFB 
support upgrading the system to a tropical storm.
 
Katia is expected to be a short-lived storm as deep-layer 
southerly shear should increase soon while Katia moves into an 
inhibiting, dry and stable surrounding environment.  As a result, a 
weakening trend is forecast through the period and is in agreement 
with the deterministic models and the statistical-dynamic SHIPS 
intensity guidance.
 
Katia is estimated to be moving north-northwestward, or 330/11 kt, 
and is situated midway between a subtropical ridge extending toward 
the west from western Africa, and a large cut-off low centered over 
the central subtropical Atlantic.  A turn toward the northwest is 
expected today followed by a a gradual turn toward the north at a 
slower forward pace around mid-period while Katia degenerates to a 
vertically shallow low-pressure system.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  02/0900Z 22.7N  29.4W   35 KT  40 MPH
 12H  02/1800Z 24.1N  30.5W   35 KT  40 MPH
 24H  03/0600Z 25.4N  31.8W   30 KT  35 MPH
 36H  03/1800Z 26.2N  33.1W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  04/0600Z 26.8N  34.3W   30 KT  35 MPH...POST-TROP/REMNT LOW
 60H  04/1800Z 27.5N  35.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  05/0600Z 28.2N  35.6W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  06/0600Z 29.6N  35.2W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  07/0600Z...DISSIPATED
 
$$
Forecaster Roberts
 
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