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| #990265 (Received by flhurricane at: 9:42 PM 22.Nov.2019) TCDAT5 Tropical Storm Sebastien Discussion Number 15 NWS National Hurricane Center Miami FL AL202019 1100 PM AST Fri Nov 22 2019 There is not much that I can add that my predecessors have not already addressed except to say that Sebastien does not know that is November near Thanksgiving. One interesting aspect tonight is that although the cloud pattern has not change at all today with the low-level center on the southern edge of the convection due to shear, and with the same Dvorak numbers, ASCAT data that just arrived showed numerous vectors of 50 kt and a few near 55 kt. On this basis, the initial intensity has been adjusted upward to 55 kt in this advisory. Sebastien has to weaken since is heading toward a hostile environment of increasing shear and cooler waters. It might not do it tonight, but the weakening process must begin within the next 24 hours or so. Both the GFS and the ECMWF open up the circulation beyond 48 hours, and with the hostile environment ahead, the NHC forecast calls for gradual weakening and dissipation in 3 days. The cyclone is moving toward the northeast of 055 degrees at 13 kt. Sebastien is embedded within the mid-latitude westerly flow, and the cyclone has nowhere to go but to continue moving northeastward with increasing forward speed. Models vary in speed, but on average they all suggest acceleration. FORECAST POSITIONS AND MAX WINDS INIT 23/0300Z 27.0N 52.2W 55 KT 65 MPH 12H 23/1200Z 28.2N 50.2W 55 KT 65 MPH 24H 24/0000Z 30.5N 46.5W 45 KT 50 MPH 36H 24/1200Z 32.6N 42.5W 40 KT 45 MPH 48H 25/0000Z 35.5N 36.0W 35 KT 40 MPH 72H 26/0000Z...DISSIPATED $$ Forecaster Avila |
