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#1150954 (Received by flhurricane at: 4:41 AM 02.Sep.2023) 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 |