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| #938418 (Received by flhurricane at: 10:45 PM 03.Sep.2018) TCDAT1 Tropical Storm Florence Discussion Number 19 NWS National Hurricane Center Miami FL AL062018 1100 PM AST Mon Sep 03 2018 Although Florence continues to produce a fairly circular area of deep convection, microwave images have revealed that there is a significant southwest-to-northeast vertical tilt of the circulation due to southwesterly shear. The initial intensity is held at 60 kt, using a blend of the Dvorak CI-numbers from TAFB and SAB. This estimate is a little below the latest automated Dvorak values from CIMSS at the University of Wisconsin. The strong tropical storm is moving west-northwestward, or 285 degrees, at 12 kt steered by a subtropical ridge to its north. The storm is expected to gradually turn northwestward with a decrease in forward speed during the next several days as it moves toward a persistent weakness in the subtropical ridge. There remains a fair amount of spread in the guidance, especially in the 3- to 5-day time period, but the consensus aids have changed little this cycle. Therefore, no significant changes were made to the previous forecast, and this one lies near the middle of the guidance envelope. Little change in strength is expected through early Tuesday as Florence remains over marginally warm waters and in moderate wind shear conditions. Slight weakening is expected during the middle part of the week due to a gradual increase in southwesterly or westerly shear. Beyond that time, however, the shear is expected to decrease and Florence will be over much warmer waters. Therefore, slow strengthening is shown at the end of the forecast period. This forecast is unchanged from the previous one, and is in good agreement with the HCCA guidance. The 34- and 50-kt initial wind radii have been expanded outward based on recent ASCAT passes. FORECAST POSITIONS AND MAX WINDS INIT 04/0300Z 18.9N 41.0W 60 KT 70 MPH 12H 04/1200Z 19.4N 42.7W 60 KT 70 MPH 24H 05/0000Z 20.1N 44.9W 55 KT 65 MPH 36H 05/1200Z 21.1N 47.2W 55 KT 65 MPH 48H 06/0000Z 22.1N 49.5W 50 KT 60 MPH 72H 07/0000Z 24.5N 53.1W 50 KT 60 MPH 96H 08/0000Z 26.8N 55.8W 55 KT 65 MPH 120H 09/0000Z 28.4N 57.8W 60 KT 70 MPH $$ Forecaster Cangialosi |
