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Tropical Storm Victor Forecast Discussion Number 5
2021-09-30 16:54:32| National Hurricane Center (Atlantic)
Issued at 200 PM CVT Thu Sep 30 2021 000 WTNT45 KNHC 301454 TCDAT5 Tropical Storm Victor Discussion Number 5 NWS National Hurricane Center Miami FL AL202021 200 PM CVT Thu Sep 30 2021 Victor remains a sprawling tropical storm with numerous curved bands surrounding the center. The associated convection remains most organized on the storm's west side. The latest Dvorak estimates are largely unchanged and range from 35 to 45 kt. In addition, an ASCAT-B pass from around 12Z showed maximum winds in the 35-40 kt range. Based on all of this data, the initial intensity is held at 40 kt. The ASCAT data also showed that the wind field is quite broad with tropical-storm-force winds extending about 90 n mi north of the center. Victor is still moving west-northwestward, or 290 degrees, at 12 kt. The storm is forecast to continue on that same general track for another day or so as it remains on the south side of a deep-layer ridge over the subtropical eastern Atlantic. By late Friday, a mid- to upper-level low is expected to form over the central Atlantic, and that feature should erode the western portion of the ridge. As a result, Victor is expected to turn northwestward by the weekend and then northward early next week when it is forecast to move in the flow between the ridge and the low. The model tracks have converged compared to yesterday, but the ECMWF remains the slowest and westernmost solution and the HWRF is still the easternmost model. The NHC track forecast is nudged to the west of the previous one and lies close to the various consensus aids and is in fair agreement with the GFS. The storm has about another 36 hours in conducive environmental conditions of very low wind shear, a moist mid-level airmass, and warm 28-29 degree C SSTs. Therefore, intensification seems likely during that time period, but given the broad nature of the system's wind field, Victor will likely gain strength slowly during that time period. However, in a couple of days, the models show a significant increase in southwesterly shear and a progressively drier airmass. These negative factors for the storm along with slightly cooler SSTs should cause Victor to lose strength. In fact, some of the models suggest that Victor could dissipate by the end of the forecast period. The new NHC intensity forecast is a little lower than the previous one. It should be noted that although this forecast no longer explicitly shows Victor becoming a hurricane, it could occur in a day or two before conditions become hostile. This forecast lies near the high end of the model guidance. FORECAST POSITIONS AND MAX WINDS INIT 30/1500Z 9.5N 28.9W 40 KT 45 MPH 12H 01/0000Z 10.2N 30.4W 50 KT 60 MPH 24H 01/1200Z 11.1N 32.3W 60 KT 70 MPH 36H 02/0000Z 12.4N 34.0W 60 KT 70 MPH 48H 02/1200Z 13.9N 35.5W 55 KT 65 MPH 60H 03/0000Z 15.7N 37.2W 50 KT 60 MPH 72H 03/1200Z 17.9N 39.0W 45 KT 50 MPH 96H 04/1200Z 23.2N 41.8W 35 KT 40 MPH 120H 05/1200Z 28.0N 42.4W 30 KT 35 MPH $$ Forecaster Cangialosi
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