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| #981676 (Received by flhurricane at: 11:06 AM 09.Sep.2019) TCDAT3 Tropical Storm Gabrielle Discussion Number 25 NWS National Hurricane Center Miami FL AL082019 Issued by the NWS Weather Prediction Center College Park MD 1100 AM AST Mon Sep 09 2019 Satellite images indicate that deep convection has increased overnight and become more symmetric around the center of Gabrielle. Still, ASCAT data show maximum winds of only about 40 kt, suggestive that this convective burst hasn`t changed the intensity much. The initial wind speed is set to 45 kt, near the TAFB satellite estimate and a little above the ASCAT data to account for undersampling. Gabrielle has turned northeastward and picked up some speed. The system is expected to move at an increasing pace in a similar direction over the next few days as it is picked up by a mid-latitude trough. Model guidance is tightly clustered around the previous NHC prediction, and no significant changes were made to the prior NHC track forecast. The storm has about a day over marginally warm waters before it crosses the north wall of the Gulf Stream into much colder waters. Gabrielle is forecast to transition into an extratropical low by Tuesday due to an increase in shear and baroclinicity from an approaching cold front. The intensity forecast was reduced slightly from the previous one and is in close agreement with a blend of the GFS/ECMWF wind speed forecasts, which should best handle this extratropical transition scenario. FORECAST POSITIONS AND MAX WINDS INIT 09/1500Z 39.0N 47.3W 45 KT 50 MPH 12H 10/0000Z 40.9N 44.7W 45 KT 50 MPH 24H 10/1200Z 43.4N 40.2W 45 KT 50 MPH 36H 11/0000Z 46.4N 34.7W 40 KT 45 MPH...POST-TROP/EXTRATROP 48H 11/1200Z 50.1N 26.9W 35 KT 40 MPH...POST-TROP/EXTRATROP 72H 12/1200Z 57.5N 5.5W 30 KT 35 MPH...POST-TROP/EXTRATROP 96H 13/1200Z...DISSIPATED $$ Forecaster Taylor/Blake |