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| #1108714 (Received by flhurricane at: 11:00 AM 24.Sep.2022) TCDAT3 Tropical Storm Gaston Discussion Number 17 NWS National Hurricane Center Miami FL AL082022 300 PM GMT Sat Sep 24 2022 Gaston has lost most of its deep convection and it is currently an exposed low-level circulation. The closest relatively deep convective activity is south of Pico Island over 100 miles away from the center and likely terrain-induced. Though a recent scatterometer pass missed the center of Gaston, it did show an area of tropical-storm-force winds of around 35 kt to the east of the center. Therefore, the initial intensity has been lowered to 40 kt, slightly higher than the satellite intensity estimates. Hostile environmental conditions have weakened Gaston considerably. The strong vertical wind shear and dry mid-level humidities are not expected to improve for the remainder of the forecast period, and additional weakening is likely. The official forecast is similar to the previous prediction and still shows Gaston becoming fully post-tropical within 12 hours. A couple of the global models, however, indicate a mid-latitude shortwave trough/baroclinic zone interacting with post-tropical Gaston early Sunday morning could develop isolated deep convection, but this should be a short-lived event. The storm is moving west-southwestward at an estimated 245/8 kt. A building mid-level ridge to the north is expected to steer Gaston to the west through Monday morning, and to the west-southwest until it dissipates near the end of the week. The NHC forecast track is shifted slightly south of the previous advisory track, likely due to the southern shift of the initial position. Key Messages: 1. Tropical storm conditions over the western and central Azores today should diminish today as Gaston moves away from the islands. 2. Gaston is expected to produce heavy rainfall over the western and central Azores through Saturday. This rainfall may result in landslides and areas of flooding. FORECAST POSITIONS AND MAX WINDS INIT 24/1500Z 38.0N 30.8W 40 KT 45 MPH 12H 25/0000Z 38.2N 32.5W 40 KT 45 MPH...POST-TROPICAL 24H 25/1200Z 38.4N 35.1W 35 KT 40 MPH...POST-TROPICAL 36H 26/0000Z 38.2N 37.0W 35 KT 40 MPH...POST-TROPICAL 48H 26/1200Z 37.5N 39.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 60H 27/0000Z 36.7N 40.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 27/1200Z 35.6N 43.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 28/1200Z 33.0N 48.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 29/1200Z...DISSIPATED $$ Forecaster Bucci |
