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| #1108847 (Received by flhurricane at: 4:54 AM 25.Sep.2022) TCDAT3 Tropical Storm Gaston Discussion Number 20 NWS National Hurricane Center Miami FL AL082022 900 AM GMT Sun Sep 25 2022 Gaston continues to generate an area of deep convection near and to the north of the center, as the interaction with the upper-level trough mentioned in the previous advisory continues to provide a favorable environment. The initial intensity remains 45 kt based on the earlier scatterometer data and a satellite intensity estimate of 45 kt from TAFB. The global models suggest that the favorable trough interaction should end in the next 12 h or so, and after that time Gaston should experience strong northwesterly shear in a convergent upper-level environment. This, combined with cool sea surface temperatures of 24-25C and a dry airmass should cause the convection to dissipate and Gaston to become post-tropical. The new intensity forecast has minor adjustments from the previous forecast, with the most significant change being keep the system as a tropical cyclone at the 12 h point. Gaston has moved a little to the right of the previous forecast with the initial motion 285/9. A building low- to mid-level ridge to the north and northwest of the cyclone should cause it to turn westward later today and then west-southwestward, with that motion continuing until the system dissipates. Since the last advisory, the track guidance has shifted southward in the 24-72 h period. So, the new forecast track is also shifted southward, with the new track just to the north of the consensus models. Key Messages: 1. Tropical storm conditions over the western Azores should diminish by midday as Gaston moves away from the islands. 2. Gaston is expected to produce heavy rainfall over the western and central Azores through midday. This rainfall may result in landslides and areas of flooding. FORECAST POSITIONS AND MAX WINDS INIT 25/0900Z 39.0N 34.5W 45 KT 50 MPH 12H 25/1800Z 39.0N 36.5W 40 KT 45 MPH 24H 26/0600Z 38.7N 38.4W 35 KT 40 MPH...POST-TROPICAL 36H 26/1800Z 38.1N 40.3W 30 KT 35 MPH...POST-TROP/REMNT LOW 48H 27/0600Z 37.5N 42.6W 30 KT 35 MPH...POST-TROP/REMNT LOW 60H 27/1800Z 36.8N 45.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 28/0600Z 36.1N 48.4W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 29/0600Z...DISSIPATED $$ Forecaster Beven |
