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#1150996 (Received by flhurricane at: 10:38 AM 02.Sep.2023) TCDAT4 Tropical Storm Katia Discussion Number 5 NWS National Hurricane Center Miami FL AL122023 200 PM CVT Sat Sep 02 2023 Satellite images indicate the center of Katia is on the southern side of a large central dense overcast. Scatterometer data from this morning indicated maximum winds were at least 40-45 kt, and the latest TAFB Dvorak estimate was 45 kt. The initial wind speed is raised to 45 kt from the last full advisory, similar to the morning update statement. Katia continues moving north-northwestward, or 330/10 kt. The motion should gradually bend toward the northwest today due to the storm moving between a large middle- to upper-level low to the west and a narrow mid-latitude ridge over the eastern Atlantic. The northwestward motion is likely to continue until about Monday, when the system becomes weaker and Katia gets stuck in the low-level subtropical ridge. The only notable change to the track forecast is that it has been adjusted to the east in the short-term due to the initial position and is very close to the previous one at the end. The storm is probably near its peak intensity with all models showing an increase in dry mid-level air near the center later today. Combined with moderate southerly shear, this should be enough to choke off deep convection in Katia's core and cause gradual weakening. In about 2 days, the environment becomes quite dry, which should finish off any remaining thunderstorm activity, and Katia is forecast to degenerate into a remnant low at that time. The NHC intensity forecast is raised early on to reflect the higher initial wind speed and is blended back with the guidance by the end of the forecast period. FORECAST POSITIONS AND MAX WINDS INIT 02/1500Z 23.9N 29.7W 45 KT 50 MPH 12H 03/0000Z 25.1N 30.8W 45 KT 50 MPH 24H 03/1200Z 26.2N 32.1W 40 KT 45 MPH 36H 04/0000Z 27.0N 33.5W 35 KT 40 MPH 48H 04/1200Z 27.6N 34.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 60H 05/0000Z 28.5N 35.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 05/1200Z 29.1N 36.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 06/1200Z...DISSIPATED $$ Forecaster Blake |