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| #1108803 (Received by flhurricane at: 10:45 PM 24.Sep.2022) TCDAT3 Tropical Storm Gaston Discussion Number 19 NWS National Hurricane Center Miami FL AL082022 300 AM GMT Sun Sep 25 2022 Gaston has been interacting with an upper-level trough just to its west for the past several hours, which has helped to regenerate deep convection over the northern semicircle. This has bought Gaston some more time as a tropical cyclone. A pair of recent scatterometer overpasses revealed a swath of 35-42 kt winds over the northern semicircle of the tropical storm, which indicates that it is stronger than previously estimated. Assuming some undersampling by the scatterometer, the initial intensity has been adjusted to 45 kt to reflect this new data. The upper trough that is helping to maintain the deep convection is forecast to lift northward later this morning and be replaced by a ridge, which should induce strong northwesterly shear over Gaston. The combination of this shear, relatively cool SSTs of about 24 degrees C, and the presence of dry air should cause Gaston`s current convection to dissipate today, resulting in the system becoming post-tropical. The NHC intensity forecast was adjusted higher through 24 h due to the adjusted initial intensity and is unchanged from the previous forecast after that time. Gaston continues its westward motion at 10 kt to the south of a mid-level ridge. By Monday, the cyclone is forecast to turn west-southwestward and possibly southwestward as the ridge builds its northwest. The latest NHC track forecast is little changed from the previous one and closely follows the track consensus guidance. 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 25/0300Z 38.6N 33.4W 45 KT 50 MPH 12H 25/1200Z 38.9N 35.3W 45 KT 50 MPH...POST-TROPICAL 24H 26/0000Z 38.7N 37.6W 35 KT 40 MPH...POST-TROPICAL 36H 26/1200Z 38.4N 39.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 48H 27/0000Z 37.9N 41.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 60H 27/1200Z 37.2N 44.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 28/0000Z 36.8N 46.6W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 29/0000Z...DISSIPATED $$ Forecaster Latto |
