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| #938171 (Received by flhurricane at: 4:48 PM 02.Sep.2018) TCDAT1 Tropical Storm Florence Discussion Number 14 NWS National Hurricane Center Miami FL AL062018 500 PM AST Sun Sep 02 2018 Florence`s cloud pattern is characterized by a low-level center partially displaced to the west of the coldest cloud tops, which have expanded in coverage recently. A blend of the latest satellite classifications supports maintaining an intensity of 45 kt for this advisory package. Little change in strength is expected for much of the forecast period, as Florence will be moving through an environment characterized by moderate shear and marginal SSTs for the next 3 days. By the end of the forecast period, the SSTs begin to warm up, which should result in some restrengthening. The new NHC intensity forecast is similar to the previous one and is closest to the SHIPS model forecast. The initial motion estimate is 285/15. Florence will be steered west-northwestward or westward for the next several days by the Atlantic subtropical ridge. There is a fair amount of north-south spread in the guidance, with the GFS, GEFS ensemble mean and HWRF on the right side of the envelope and the ECMWF, ECMWF mean and UKMET on the left. This spread is likely due to large differences in the vertical structure of the cyclone, with the ECMWF and UKMET having a much weaker vortex at 500 mb compared to the GFS in 3-4 days. Given the difficulty in forecasting these types of structural changes, the NHC forecast lies in the middle of the guidance envelope and is close to the multi-model consensus aids through the forecast period. This forecast is largely an update of the previous NHC prediction. FORECAST POSITIONS AND MAX WINDS INIT 02/2100Z 17.4N 34.6W 45 KT 50 MPH 12H 03/0600Z 17.7N 36.9W 45 KT 50 MPH 24H 03/1800Z 18.2N 39.6W 45 KT 50 MPH 36H 04/0600Z 18.6N 41.9W 45 KT 50 MPH 48H 04/1800Z 19.3N 44.0W 45 KT 50 MPH 72H 05/1800Z 21.1N 48.3W 45 KT 50 MPH 96H 06/1800Z 23.0N 52.0W 45 KT 50 MPH 120H 07/1800Z 25.5N 56.0W 55 KT 65 MPH $$ Forecaster Brennan |
