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| #1153586 (Received by flhurricane at: 10:45 PM 19.Sep.2023) TCDAT5 Hurricane Nigel Discussion Number 19 NWS National Hurricane Center Miami FL AL152023 1100 PM AST Tue Sep 19 2023 Nigel appears to be succumbing to the effects of southerly wind shear this evening. Deep convection in the eastern portion of the circulation has eroded, and the eyewall has opened to the northeast. Still, subjective and objective satellite intensity estimates range between 102 to 77 kt. The initial intensity is held at a possibly generous 85 kt, to represent a blend of these estimates. Global model guidance suggests oceanic and environmental conditions could be marginally conducive for strengthening for only a short while longer. In a day or so, Nigel is expected to move over waters cooler than 26 degrees Celsius, and the deep-layer vertical wind shear is forecast to significantly increase. As a result, the latest NHC intensity forecast shows a slightly lower peak intensity of 90 kt in the short-term forecast, followed by steady weakening through the remainder of the forecast period. Nigel should become a powerful extratropical cyclone in about 60 h. The hurricane is moving toward the north at 13 kt on the western edge of a mid-level ridge over the central subtropical Atlantic. By Wednesday, Nigel is expected to turn northeastward and accelerate in the flow of a deep-layer trough located over the northeastern United States and Atlantic Canada. In the first few days, there is little spread in the track guidance envelope, and only minor adjustments have been made to the latest official forecast. As Nigel moves poleward, the extratropical low is forecast to interact with a broader cyclonic circulation over the north Atlantic on days 4 and 5, which introduces increased track uncertainty late in the period. FORECAST POSITIONS AND MAX WINDS INIT 20/0300Z 33.2N 54.7W 85 KT 100 MPH 12H 20/1200Z 35.3N 54.2W 90 KT 105 MPH 24H 21/0000Z 38.4N 51.3W 85 KT 100 MPH 36H 21/1200Z 41.6N 46.1W 75 KT 85 MPH 48H 22/0000Z 44.4N 39.0W 65 KT 75 MPH 60H 22/1200Z 47.5N 31.4W 55 KT 65 MPH...POST-TROP/EXTRATROP 72H 23/0000Z 50.8N 25.9W 50 KT 60 MPH...POST-TROP/EXTRATROP 96H 24/0000Z 57.1N 22.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 25/0000Z 58.9N 21.5W 35 KT 40 MPH...POST-TROP/EXTRATROP $$ Forecaster Bucci |
