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Tropical Storm Victor Forecast Discussion Number 9
2021-10-01 16:52:25| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Fri Oct 01 2021 000 WTNT45 KNHC 011452 TCDAT5 Tropical Storm Victor Discussion Number 9 NWS National Hurricane Center Miami FL AL202021 1100 AM AST Fri Oct 01 2021 Since the last advisory, Victor's deep convection has become limited to the northern portion of its circulation. Convective outflow is limited to the south, which indicates that the changes in the structure of the tropical storm are due at least in part to southerly wind shear. Microwave and ASCAT data between 0800 and 1200 UTC also indicate that the center of Victor has become elongated, and may be trying to reform to the north, closer to the convection. Even with that reformation, an 1128 ASCAT-B overpass revealed that the center of Victor is located substantially south of previous estimates, which has necessitated a significant change to the track forecast. With the new position, the initial motion estimate is now 295/13 kt. The tropical storm is still generally expected to turn northwestward over the weekend and then continue on that heading through early next week, steered by the southwest periphery of a mid-level ridge centered over the eastern Atlantic. Nearly all of the dynamical models are showing this turn occuring slightly later than earlier forecasts, which results in a track well to the west of the previous NHC forecast. Combined with the updated analysis of Victor's position, the new NHC forecast has been shifted over 100 n mi to the southwest by day 4. However, this is still on the far east side of the guidance envelope so additional changes to the track forecast might be needed this afternoon. The aforementioned ASCAT data showed peak winds near 50 kt, which supports an intensity of 55 kt, assuming a little undersampling due to the resolution of the instrument. The intensity analysis is also supported by the latest TAFB Dvorak estimate. Despite the large changes to the track forecast, no change of note was made to the intensity forecast. Increasing shear and a dry surrounding environment should cause Victor to weaken during the next few days. Some models even indicate it could dissipate before the end of the forecast period. The NHC forecast is based on the intensity model consensus. FORECAST POSITIONS AND MAX WINDS INIT 01/1500Z 11.5N 33.5W 55 KT 65 MPH 12H 02/0000Z 12.0N 34.8W 55 KT 65 MPH 24H 02/1200Z 13.1N 36.4W 50 KT 60 MPH 36H 03/0000Z 14.7N 38.1W 45 KT 50 MPH 48H 03/1200Z 16.6N 40.0W 45 KT 50 MPH 60H 04/0000Z 18.7N 42.1W 40 KT 45 MPH 72H 04/1200Z 20.6N 43.9W 35 KT 40 MPH 96H 05/1200Z 23.6N 46.5W 30 KT 35 MPH 120H 06/1200Z 27.1N 46.9W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster D. Zelinsky
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