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| #1156800 (Received by flhurricane at: 4:38 AM 11.Oct.2023) TCDAT4 Tropical Storm Sean Discussion Number 2 NWS National Hurricane Center Miami FL AL192023 500 AM AST Wed Oct 11 2023 Satellite images indicate that deep convection has increased near the center of the cyclone, with some curved banding features located both north and south of the center. Subjective and objective Dvorak estimates from TAFB/SAB/UW-CIMSS range from 30-47 kt, and a conservative blend of this data gives an initial wind speed of 35 kt for this advisory. Thus Tropical Storm Sean has formed, the 19th named storm in this busy 2023 Atlantic season. Sean could intensify a bit more during the next day or so before increasing southerly shear affects the core of the cyclone. Some hints of this shear can already be seen in cirrus cloud motions from convective activity northwest of the tropical cyclone. Thereafter, moderate-to-strong shear is expected to generally cancel out the enhancing effects of a relatively moist and unstable environment, leading to little net change for a few days. By the end of the week, while the shear could weaken, global models are generally showing an influx of drier mid-level air along with upper-level convergence, which would typically weaken any associated deep convection. Many of the regional hurricane models, however, actually show some strengthening at long range, but they have been inconsistent at that time frame. The NHC forecast leans more on the global models for now, similar to the previous forecast and the model consensus, and continues to show Sean becoming a remnant low on day 5. The storm is moving west-northwestward at about 11 kt. A mid-level ridge located to the northeast of the cyclone should steer Sean west-northwestward to northwestward through Friday. Very late in the forecast period, a bend back toward the west-northwest is anticipated as the cyclone weakens and is steered by the low-level trade wind flow. The new NHC track forecast is adjusted a bit west of the last one at longer range, between the model-consensus and corrected-consensus aids, which favors the weaker track aids on the left side of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 11/0900Z 10.3N 33.1W 35 KT 40 MPH 12H 11/1800Z 10.7N 34.8W 40 KT 45 MPH 24H 12/0600Z 11.2N 36.5W 40 KT 45 MPH 36H 12/1800Z 11.8N 38.0W 40 KT 45 MPH 48H 13/0600Z 12.6N 39.5W 40 KT 45 MPH 60H 13/1800Z 13.5N 40.8W 40 KT 45 MPH 72H 14/0600Z 14.5N 42.0W 35 KT 40 MPH 96H 15/0600Z 16.7N 44.6W 35 KT 40 MPH 120H 16/0600Z 18.0N 47.0W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ Forecaster Blake |
