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Tropical Storm Paulette Forecast Discussion Number 10
2020-09-09 10:42:33| National Hurricane Center (Atlantic)
Issued at 500 AM AST Wed Sep 09 2020 000 WTNT42 KNHC 090842 TCDAT2 Tropical Storm Paulette Discussion Number 10 NWS National Hurricane Center Miami FL AL172020 500 AM AST Wed Sep 09 2020 The 20-30 kt of southwesterly shear continues to have a significant impact on Paulette's inner core. A 0615 UTC Global Precipitation Measurement (GPM) Microwave Imager overpass showed a severely sheared tropical cyclone with the exposed surface circulation displaced to the south of the cloud canopy. Although the objective ADT and an earlier SATCON analysis yield 45 kt, The initial intensity is held at a generous 50 kt for this advisory in deference to last night's scatterometer pass showing a few 50 kt winds. In addition to the moderate, persistent shear, the RAMMB/CIRA Average Vertical Instability parameter time series analysis revealed a higher than normal (1995-2010) statically stable environment, another potential inhibiting factor. This was further supported by the statistical-dynamical intensity models showing a rather parched mid-troposphere (less than 58%). Therefore, slow weakening of Paulette is forecast during the next few days. Toward the end of the period, the ECMWF and FV3 SHIPS intensity models continue to indicate a more southerly, diffluent pattern which should aid in some restrengthening, and this is indicated in the NHC forecast. The initial motion is estimated to be westward, or 280/7 kt. Paulette should turn west-northwestward later today and westward on Thursday around the southwestern periphery of a subtropical ridge to the northeast of the cyclone. A turn northwestward is predicted on Saturday as Paulette moves further into a growing weakness in the ridge over the western Atlantic. The official forecast is an update of the previous one through 72 hrs, then is shifted to the left through day 5 to lies between the HCCA consensus and the the HFIP/NUOPC Project's 5EMN 133 member multi-model ensemble mean. FORECAST POSITIONS AND MAX WINDS INIT 09/0900Z 19.2N 45.6W 50 KT 60 MPH 12H 09/1800Z 19.7N 46.9W 50 KT 60 MPH 24H 10/0600Z 20.3N 49.0W 45 KT 50 MPH 36H 10/1800Z 20.5N 50.7W 45 KT 50 MPH 48H 11/0600Z 20.8N 52.2W 40 KT 45 MPH 60H 11/1800Z 21.4N 53.6W 40 KT 45 MPH 72H 12/0600Z 22.7N 54.9W 40 KT 45 MPH 96H 13/0600Z 25.9N 58.2W 45 KT 50 MPH 120H 14/0600Z 28.7N 61.4W 50 KT 60 MPH $$ Forecaster Roberts
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