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| #1108090 (Received by flhurricane at: 4:45 PM 20.Sep.2022) TCDAT3 Tropical Storm Gaston Discussion Number 2 NWS National Hurricane Center Miami FL AL082022 Issued by the NWS Weather Prediction Center College Park MD 900 PM GMT Tue Sep 20 2022 Satellite images indicate that deep convection is persisting near and to the north of the center of the cyclone during the past several hours. Drifting buoy 44857 recently reported a minimum pressure of 1009 mb near the center of the low, which is a 8 mb decrease from earlier today. An ASCAT-C pass from several hours ago showed maximum winds of about 35 kt in the northeast and northwest quadrants. Based on that data, the initial intensity is increased to 35 kt, making the system Tropical Storm Gaston. Gaston has turned north-northeastward and is moving a little faster than before. The initial motion estimate is 020/15 kt. A turn to the east is expected in a couple of days when the tropical storm moves along the northern periphery of a subtropical ridge. By the end of the week, however, Gaston is expected to stall to the west of the Azores in weak steering currents as high pressure builds near and to the north of the cyclone. After that time, a turn to the northwest or north is expected as Gaston moves in the flow between Hurricane Fiona and the ridge. The models have trended a little faster this cycle, and the NHC track forecast has been adjusted accordingly. Gaston is currently moving over relatively warm water, in a region of upper-level diffluence within a somewhat favorable moist environment. These factors should allow the system to strengthen slowly during the next day or two. However, after that time, much cooler SSTs, drier air, and an increase in westerly shear should end the strengthening trend. The system is expected to become extratropical on Saturday when it moves over SSTs just above 20C and merges with a mid- to upper-level trough. The NHC intensity forecast is about the same as the previous one and near the middle of the guidance envelope. Interests in the Azores should monitor the forecast for Gaston. FORECAST POSITIONS AND MAX WINDS INIT 20/2100Z 34.7N 44.4W 35 KT 40 MPH 12H 21/0600Z 36.5N 43.3W 40 KT 45 MPH 24H 21/1800Z 38.3N 40.9W 45 KT 50 MPH 36H 22/0600Z 39.4N 38.0W 50 KT 60 MPH 48H 22/1800Z 40.1N 35.3W 50 KT 60 MPH 60H 23/0600Z 40.3N 33.1W 50 KT 60 MPH 72H 23/1800Z 40.4N 32.5W 50 KT 60 MPH 96H 24/1800Z 41.0N 32.5W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 25/1800Z 44.0N 35.3W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Cangialosi/Kebede |
