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#981506 (Received by flhurricane at: 4:42 PM 07.Sep.2019) TCDAT3 Tropical Storm Gabrielle Discussion Number 18 NWS National Hurricane Center Miami FL AL082019 500 PM AST Sat Sep 07 2019 Gabrielle is still a disorganized tropical cyclone. The center is definitely more apparent--after its morning re-formation--but it appears to be wobbling around within a larger oval-shaped circulation. Most of the deep convection is also displaced to the west and southwest of the center due to about 20 kt of easterly shear. The initial intensity remains 45 kt based on earlier scatterometer data. The cyclone has been rotating around the northeastern side of a mid- to upper-level low, but as this low weakens, Gabrielle is expected to recurve around the western side of a mid-tropospheric high located near the Azores. Gabrielle should then get picked up by the mid-latitude westerlies in about 48 hours, at which point it will accelerate northeastward toward the north Atlantic. The track models remain in good agreement on Gabrielle`s future trajectory, but there are some speed differences, particularly between the faster GFS and slower ECMWF once the cyclone becomes extratropical. The updated NHC forecast splits the difference, lying near the various consensus models, which makes it just a little west of the previous forecast during the first 36 hours. Gabrielle has about another 36 hours over waters that are 26C or warmer, but the moderate-to-strong vertical shear currently affecting the system is likely to continue, and then increase significantly starting in 48 hours. Therefore, only modest strengthening is anticipated, and the NHC intensity forecast is now near the high end of the intensity models. All the global models indicate that Gabrielle should become an extratropical cyclone by 72 hours, and then it should dissipate by 120 hours. FORECAST POSITIONS AND MAX WINDS INIT 07/2100Z 31.9N 46.5W 45 KT 50 MPH 12H 08/0600Z 32.9N 48.3W 50 KT 60 MPH 24H 08/1800Z 34.9N 49.4W 55 KT 65 MPH 36H 09/0600Z 37.7N 48.7W 60 KT 70 MPH 48H 09/1800Z 40.8N 45.6W 60 KT 70 MPH 72H 10/1800Z 46.0N 33.5W 55 KT 65 MPH...POST-TROP/EXTRATROP 96H 11/1800Z 52.0N 17.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 12/1800Z...DISSIPATED $$ Forecaster Berg |