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| #1152789 (Received by flhurricane at: 12:02 PM 14.Sep.2023) TCDAT4 Hurricane Margot Discussion Number 29 NWS National Hurricane Center Miami FL AL142023 Issued by the NWS Weather Prediction Center College Park MD 300 PM GMT Thu Sep 14 2023 The double-eyewall structure of Margot has changed this morning, with the inner-eye almost completely dissipated, and the outer eyewall has taken over as the dominant feature. This is confirmed by scatterometer data from ASCAT-B and a SAR pass around 9 UTC. The initial wind speed is set to 70 kt, a compromise between higher SAR estimates and Dvorak values closer to 65 kt. Note that the hurricane- and storm-force wind radii have been changed/expanded significantly due to the SAR/scatterometer data. Margot has turned further to the right, or 030/5. A blocking ridge over the north-central Atlantic should force Margot to slow down and execute a clockwise loop during the next few days. After the ridge shifts eastward, the hurricane could gain some latitude and begin to move more to the northeast at the end of the forecast period. Model guidance is coming into better agreement on this solution, although there is considerable spread at long range with the GFS faster and more to the northeast than the ECMWF-based guidance. The new NHC forecast is shifted southward in the near term with the GFS coming more into line with the other guidance, and ends up in almost the same spot as the last forecast by day 5. The hurricane should gradually weaken as the large system slows down and upwells cooler water, along with Margot crossing over its own path. Additionally, there is plenty of mid-level dry air in the surrounding environment that could be mixed in the core eventually. The updated forecast is adjusted higher initially because of the current intensity, but is blended back with the previous forecast and consensus aids at longer term. Margot could become a post-tropical cyclone without deep convection early next week, but it really depends on how it handles the more hostile conditions. Given how resilient this season's tropical cyclones have been, it could be optimistic that Margot is post-tropical on day 5. FORECAST POSITIONS AND MAX WINDS INIT 14/1500Z 36.5N 39.8W 70 KT 80 MPH 12H 15/0000Z 36.8N 39.3W 65 KT 75 MPH 24H 15/1200Z 36.7N 38.9W 65 KT 75 MPH 36H 16/0000Z 36.2N 38.8W 60 KT 70 MPH 48H 16/1200Z 35.5N 39.5W 55 KT 65 MPH 60H 17/0000Z 35.0N 41.0W 50 KT 60 MPH 72H 17/1200Z 35.1N 42.3W 45 KT 50 MPH 96H 18/1200Z 37.5N 43.3W 45 KT 50 MPH 120H 19/1200Z 40.0N 39.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Fracasso/Blake |
