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Tropical Storm Paulette Forecast Discussion Number 9
2020-09-09 04:51:46| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Tue Sep 08 2020 000 WTNT42 KNHC 090251 TCDAT2 Tropical Storm Paulette Discussion Number 9 NWS National Hurricane Center Miami FL AL172020 1100 PM AST Tue Sep 08 2020 Microwave and satellite data suggest that vertical shear is weakening Paulette. The center is near the southern side of a large thunderstorm cluster, with the bulk of deep convection in the northeastern quadrant of the cyclone. A recent ASCAT-B pass showed maximum winds of 45-50 kt, a little lower than the other satellite estimates, and 50 kt is chosen as the initial wind speed. With Paulette already on a weakening trend, it seems that the window for significant strengthening has closed. More likely, a gradual decay of the storm is anticipated due to moderate or strong shear during the next few days. This shear could abate by the end of the forecast period due to Paulette moving around the northeastern side of a large mid-to-upper level low, which is a common position for the re-intensification of a tropical cyclone after encountering the mid-oceanic trough. The new forecast is lowered from the previous one for the first few days and then raised slightly at the longer ranges. This is consistent with a blend of the intensity model consensus, leaning toward the NOAA corrected-consensus guidance at the end. The storm is moving northwestward at about 8 kt. There has been some convergence of the model guidance during the next few days as Paulette should move west-northwestward tomorrow and westward on Thursday around a mid-level ridge. Thus, little change has been made from the previous forecast during the first 48-72h. Afterwards, the forecast is shifted to the north by 45-60 n mi under the assumption that Paulette stays coherent as a tropical cyclone and takes a turn to the northwest this weekend on the eastern flank of the aforementioned mid-to-upper level low. The new track forecast is northeast of the model consensus and places less emphasis on models, like the 12Z ECMWF, which show Paulette staying weaker and missing the full influence of the low. FORECAST POSITIONS AND MAX WINDS INIT 09/0300Z 19.2N 45.0W 50 KT 60 MPH 12H 09/1200Z 19.8N 46.2W 50 KT 60 MPH 24H 10/0000Z 20.2N 48.1W 50 KT 60 MPH 36H 10/1200Z 20.6N 50.0W 45 KT 50 MPH 48H 11/0000Z 20.8N 51.7W 45 KT 50 MPH 60H 11/1200Z 21.1N 52.9W 40 KT 45 MPH 72H 12/0000Z 21.9N 53.8W 40 KT 45 MPH 96H 13/0000Z 24.4N 55.7W 45 KT 50 MPH 120H 14/0000Z 27.5N 59.0W 55 KT 65 MPH $$ Forecaster Blake
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