[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 020840
TCDAT4

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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