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| #1153939 (Received by flhurricane at: 4:41 AM 22.Sep.2023) TCDAT5 Post-Tropical Cyclone Nigel Discussion Number 28 NWS National Hurricane Center Miami FL AL152023 900 AM GMT Fri Sep 22 2023 Nigel has completed its transition to an extra-tropical cyclone this morning. Convection from earlier has waned, and is well displaced from the exposed low-level center. Based on a blend of an earlier partial ASCAT pass and subjective Dvorak satellite intensity estimates, the initial intensity is lowered to 60 kt for this advisory. The system is encountering very strong vertical wind shear and ocean temperatures below 20 degrees Celsius. The system is forecast to continue to gradually weaken over the next couple of days. However, the system will remain a strong extra-tropical cyclone with an expanding wind field. The NHC intensity forecast is similar to the previous advisory and lies near the model consensus. Nigel continues to race northeastward at 32 kt. A northeastward motion is forecast to continue the next day or so, as it remains in the flow along the southern edge of a deep mid-latitude trough. Afterwards, Nigel should rotate around the eastern side of a large extratropical cyclone over the North Atlantic, with the two extratropical systems merging in about 48 h. The model guidance remains in fairly good agreement, and the NHC forecast lies in the center of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 22/0900Z 46.3N 32.6W 60 KT 70 MPH...POST-TROPICAL 12H 22/1800Z 48.8N 27.2W 50 KT 60 MPH...POST-TROP/EXTRATROP 24H 23/0600Z 53.0N 23.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 36H 23/1800Z 56.4N 23.3W 50 KT 60 MPH...POST-TROP/EXTRATROP 48H 24/0600Z...DISSIPATED $$ Forecaster Kelly |
