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| #1108529 (Received by flhurricane at: 11:06 AM 23.Sep.2022) TCDAT3 Tropical Storm Gaston Discussion Number 13 NWS National Hurricane Center Miami FL AL082022 300 PM GMT Fri Sep 23 2022 Gaston is improving in satellite presentation this morning. Convection is re-forming and wrapping around the northern and western sides of the circulation. A recent scatterometer pass showed that Gaston was slightly stronger than the previous advisory and the initial intensity has been increased to 55 kt. The tropical-storm-force wind field was also expanded, especially in the northwestern quadrant based on these data. The cyclone has managed to retain its tropical characteristics for now. Global model guidance suggests moderate to strong vertical wind shear should gradually strip away convection from the core over the next day or so. In spite of the relatively hostile conditions, Gaston has managed to maintain its strength, therefore only gradual weakening is forecast until the storm merges with a shortwave trough in about 36 hours and becomes a post-tropical cyclone. The official intensity forecast has been shifted slightly higher than the previous advisory due to the initial intensity and is slightly stronger than the consensus model aids. The storm is moving east-southeastward at an estimated 120/6 kt. A sharp turn to the south is expected shortly while Gaston traverses the periphery of a mid-level ridge building to the north. Afterward, the cyclone should generally move toward the west-southwest and west, completing an anticyclone turn, through the end of the period. The NHC forecast has been nudged slightly northward once again from the previous forecast and lies between the HCCA and TVCN multi-model consensus aids. Key Messages: 1. Tropical storm conditions are occurring over portions of the western Azores, and are spreading to the central Azores. 2. Gaston is expected to produce heavy rainfall over the western and central Azores today through Saturday. This rainfall may result in landslides and areas of flooding. FORECAST POSITIONS AND MAX WINDS INIT 23/1500Z 40.2N 29.1W 55 KT 65 MPH 12H 24/0000Z 39.4N 29.0W 55 KT 65 MPH 24H 24/1200Z 38.7N 30.2W 50 KT 60 MPH 36H 25/0000Z 38.7N 32.3W 50 KT 60 MPH...POST-TROPICAL 48H 25/1200Z 38.9N 34.8W 50 KT 60 MPH...POST-TROPICAL 60H 26/0000Z 39.0N 36.7W 45 KT 50 MPH...POST-TROPICAL 72H 26/1200Z 39.0N 38.6W 40 KT 45 MPH...POST-TROPICAL 96H 27/1200Z 38.9N 42.0W 35 KT 40 MPH...POST-TROPICAL 120H 28/1200Z 37.7N 46.2W 30 KT 35 MPH...POST-TROPICAL $$ Forecaster Bucci |
