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| #1108767 (Received by flhurricane at: 5:00 PM 24.Sep.2022) TCDAT3 Tropical Storm Gaston Discussion Number 18 NWS National Hurricane Center Miami FL AL082022 900 PM GMT Sat Sep 24 2022 Gaston still lacks any deep convection near the center of its circulation. There is a burst of convection, mentioned in the previous advisory, that is now northwest of Faial island and over a hundred miles from the center of the storm. The subjective and objective Dvorak classifications have decreased to 30-40 kt. Thus, the initial intensity has been lowered to 35 kt to be a blend of these estimates. Strong vertical wind shear and dry environmental conditions continue to weaken Gaston. These adverse atmospheric conditions are not expected to improve for the remainder of the forecast period, and the storm should gradually weaken. The official forecast is slightly lower than the previous prediction due to the decrease in initial intensity. Gaston is still expected to become fully post-tropical within 12 hours. Global model simulated satellite imagery, however, indicate a mid-latitude shortwave trough interacting with post-tropical Gaston early Sunday morning could develop isolated deep convection, but this should be a short-lived event. Gaston has made its turn to the west and is moving 280/10 kt. The storm should continue to move generally westward for the next day or so as it is steered by a building ridge to the north. The ridge is then expected to turn the cyclone to the west-southwest and southwest through the end of the forecast period. The model guidance has shifted to the north this forecast cycle. The official track forecast follows the northward guidance trend and now lies on the south side of the guidance, though north of the previous advisory. Key Messages: 1. Tropical storm conditions over the western Azores should diminish overnight as Gaston moves away from the islands. 2. Gaston is expected to produce heavy rainfall over the western and central Azores through early Saturday. This rainfall may result in landslides and areas of flooding. FORECAST POSITIONS AND MAX WINDS INIT 24/2100Z 38.2N 31.8W 35 KT 40 MPH 12H 25/0600Z 38.6N 33.7W 35 KT 40 MPH...POST-TROPICAL 24H 25/1800Z 38.6N 36.1W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 26/0600Z 38.3N 38.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 48H 26/1800Z 38.0N 39.9W 30 KT 35 MPH...POST-TROP/REMNT LOW 60H 27/0600Z 37.5N 42.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 27/1800Z 37.0N 45.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 28/1800Z...DISSIPATED $$ Forecaster Bucci |
