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| #981540 (Received by flhurricane at: 10:48 PM 07.Sep.2019) TCDAT3 Tropical Storm Gabrielle Discussion Number 19 NWS National Hurricane Center Miami FL AL082019 1100 PM AST Sat Sep 07 2019 Microwave data indicate that Gabrielle has a well-organized central core. However, the convection isn`t very deep, perhaps because of dry air entrainment, with most of the convection in a band southeast of the center. The initial intensity is kept at 45 kt, which agrees well with an ASCAT-B pass of 40-45 kt and the latest TAFB fix. The storm is moving steadily west-northwestward around the southwestern side of a mid-level high over the eastern Atlantic. This high is forecast to slide eastward as the westerlies intensify due to flow around Gabrielle`s southern flank in the far north Atlantic. Models are in very good agreement overall, but there continues to be some speed differences. The NHC forecast is on the faster side of the guidance, near the NOAA corrected-consensus guidance and the previous forecast, since the typical error in the higher latitudes is to be too slow. The low-shear area that was supposed to materialize in the subtropical Atlantic near Gabrielle this weekend did not occur, and as a result there is very little guidance suggesting that the cyclone will become a hurricane. The storm still has a day or two to strengthen over relatively warm waters before shear increases markedly, and water temperatures plummet north of the Gulf Stream. The intensity forecast is reduced about 5 kt from the previous one at 36-48 h, although still above the model consensus, and is similar thereafter. All models still show extratropical transition by 72 h and dissipation by day 5. FORECAST POSITIONS AND MAX WINDS INIT 08/0300Z 32.0N 48.0W 45 KT 50 MPH 12H 08/1200Z 33.4N 49.3W 50 KT 60 MPH 24H 09/0000Z 35.8N 49.4W 55 KT 65 MPH 36H 09/1200Z 38.8N 47.6W 55 KT 65 MPH 48H 10/0000Z 41.7N 43.6W 55 KT 65 MPH 72H 11/0000Z 47.0N 31.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 96H 12/0000Z 54.5N 13.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 120H 13/0000Z...DISSIPATED $$ Forecaster Blake |
