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Tropical Storm Paulette Forecast Discussion Number 12
2020-09-09 22:31:58| National Hurricane Center (Atlantic)
Issued at 500 PM AST Wed Sep 09 2020 000 WTNT42 KNHC 092031 TCDAT2 Tropical Storm Paulette Discussion Number 12 NWS National Hurricane Center Miami FL AL172020 500 PM AST Wed Sep 09 2020 Paulette's satellite presentation has not changed since this morning, with the center exposed just to the south of the deepest convection. Between this morning's ASCAT pass and the most recent satellite classifications from TAFB and SAB, which are unchanged at T3.0 and T3.5, respectively, the maximum wind estimate remains 50 kt. Paulette continues to move into an area of stronger southwesterly shear, which is now estimated to be 25-30 kt, and this shear is likely to increase further to 30-35 kt within the next 24 hours. As a result, Paulette is expected to begin weakening by Thursday, and the NHC forecast is embedded among the tightly clustered intensity guidance during the first 2-3 days. The shear is expected to relax gradually from 48 hours and beyond and turn out of the southeast, which should allow for some restrengthening on days 3 through 5 when shear magnitudes could go as low as 10 kt. The HWRF and COAMPS-TC models in particular take full advantage of this environment and bring Paulette to hurricane intensity by day 4. The updated NHC intensity forecast is not nearly this aggressive, but it does indicate a little more strengthening at the end of the forecast period than has been shown in previous forecasts, lying closest to the statistical-dynamical guidance. Model environmental trends will be monitored, and additional intensity adjustments at the end of the forecast period will be made accordingly in subsequent forecasts. Paulette remains on a west-northwestward course (295/9 kt), located to the south of low- to mid-level ridging which extends across the central and western Atlantic. The track models suggest that when the cyclone weakens in a day or two, lower-level winds could steer the cyclone westward for a short time. However, a combination of the ridge weakening and Paulette's expected re-strengthening should cause the cyclone to turn northwestward in 2-3 days and maintain that trajectory through the end of the forecast period. The only significant change from the previous forecast is that the 5-day forecast point has been shifted westward, with the GFS, ECMWF, HWRF, and HCCA models all lying on the left side of the guidance envelope by that time. FORECAST POSITIONS AND MAX WINDS INIT 09/2100Z 20.5N 47.4W 50 KT 60 MPH 12H 10/0600Z 20.9N 48.9W 50 KT 60 MPH 24H 10/1800Z 21.4N 50.9W 45 KT 50 MPH 36H 11/0600Z 21.6N 52.7W 40 KT 45 MPH 48H 11/1800Z 22.3N 54.1W 40 KT 45 MPH 60H 12/0600Z 23.3N 55.4W 40 KT 45 MPH 72H 12/1800Z 24.8N 56.6W 45 KT 50 MPH 96H 13/1800Z 28.0N 60.5W 50 KT 60 MPH 120H 14/1800Z 30.5N 64.5W 55 KT 65 MPH $$ Forecaster Berg
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