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| #1200939 (Received by flhurricane at: 10:54 AM 29.Sep.2024) TCDAT5 Hurricane Isaac Discussion Number 15 NWS National Hurricane Center Miami FL AL102024 300 PM GMT Sun Sep 29 2024 Hurricane Isaac continues to maintain a small inner-core, which has proved resilient in an increasingly unfavorable environment characterized by strong deep-layer vertical wind shear near 30 kt and sea surface temperatures (SSTs) around 23C. The satellite appearance of the hurricane has been relatively steady this morning, with consistent bursts of deep convection near the center. The initial intensity is set to a possibly generous 65 kt, which is on the higher end of the subjective and objective intensity estimates. The tropical cyclone is forecast to track over cooler SSTs and into increasing west-southwesterly vertical wind shear, which will induce steady weakening through the forecast period. The intensity forecast is similar to the previous forecast. There is evidence on visible satellite this morning that Isaac has begun to interact with a baroclinic zone to its north and east, in addition to wrapping dry air from the northwest around the southern side of the circulation. These factors are likely to result in Isaac becoming an extratropical cyclone by Monday. Isaac`s forward motion continues to be northeastward (045/10 kt) as it is steered by deep-layer southwesterly flow. This general motion should continue for the next day or so, with a turn toward the north-northeast expected by the middle part of this week in response to a mid- to upper-level trough approaching from the west. The cyclone is then forecast to turn back towards the northeast beyond 72 hr as it tracks along the southeastern periphery of an upper-level trough. Once again, the track forecast is adjusted eastward from the previous advisory beyond the 24 hr period, in agreement with the latest consensus guidance. FORECAST POSITIONS AND MAX WINDS INIT 29/1500Z 43.2N 35.6W 65 KT 75 MPH 12H 30/0000Z 44.0N 33.6W 55 KT 65 MPH 24H 30/1200Z 45.1N 30.3W 50 KT 60 MPH...POST-TROP/EXTRATROP 36H 01/0000Z 46.6N 26.8W 45 KT 50 MPH...POST-TROP/EXTRATROP 48H 01/1200Z 48.5N 25.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 60H 02/0000Z 50.6N 24.3W 35 KT 40 MPH...POST-TROP/EXTRATROP 72H 02/1200Z 52.8N 23.1W 35 KT 40 MPH...POST-TROP/EXTRATROP 96H 03/1200Z 57.1N 18.6W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 04/1200Z 61.2N 14.2W 35 KT 40 MPH...POST-TROP/EXTRATROP $$ Forecaster Mahoney/Papin |
