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| #1149965 (Received by flhurricane at: 10:51 PM 28.Aug.2023) TCDAT3 Hurricane Franklin Discussion Number 34 NWS National Hurricane Center Miami FL AL082023 1100 PM EDT Mon Aug 28 2023 Franklin remains a powerful category 4 hurricane. Satellite images show a clear and circular eye with a solid and symmetric ring of deep convection surrounding that feature. The Air Force Hurricane Hunters have investigated Franklin during the past few hours and found 700-mb flight-level winds as high as 140 kt and maximum surface SFMR winds of 128 kt. In addition, the minimum pressure based on dropsonde data is estimated to be 926 mb. Based on these data, the initial intensity is set at 130 kt, which is close to the upper bound of category 4 status. The major hurricane is now moving due northward at 9 kt. A turn to the northeast is expected on Tuesday, with a steady increase in forward speed forecast during the next few days as the hurricane moves in progressively faster flow between a mid-level ridge over the central Atlantic and a mid- to upper-level trough over the northeastern U.S. and eastern Canada. The models are in relatively good agreement during the next 72 hours, however, they diverge significantly after that. The GFS shows a continued acceleration to the northeast with the trough eventually capturing Franklin. Conversely, the ECMWF shows the trough pulling away, leaving Franklin behind in weaker steering currents. The NHC track forecast is roughly between those very different solutions, sticking close to the various consensus aids. Franklin should maintain its strength overnight, but a steady weakening trend should begin on Tuesday as the hurricane moves over progressively cooler waters and into an environment of higher shear. Regardless, Franklin is expected to be a significant hurricane during the next few days. Franklin should complete extratropical transition in 3 to 4 days when it crosses the northern wall of the Gulf Stream Current and moves into an environment of very strong shear. The NHC intensity forecast is a little lower than the previous one and close to the HCCA and IVCN models. KEY MESSAGES: 1. Tropical storm conditions are possible on Bermuda beginning Wednesday morning, when Franklin is forecast to make its closest approach to the island. 2. Life-threatening surf and rip currents are occurring along the coast of the southeast United States. These conditions are expected to spread northward along the remainder of the U.S. east coast, Atlantic Canada, and Bermuda during the next couple of days. FORECAST POSITIONS AND MAX WINDS INIT 29/0300Z 29.4N 71.0W 130 KT 150 MPH 12H 29/1200Z 30.5N 70.8W 130 KT 150 MPH 24H 30/0000Z 32.1N 69.7W 120 KT 140 MPH 36H 30/1200Z 33.9N 67.7W 110 KT 125 MPH 48H 31/0000Z 35.8N 64.5W 100 KT 115 MPH 60H 31/1200Z 38.0N 60.3W 95 KT 110 MPH 72H 01/0000Z 40.9N 55.3W 85 KT 100 MPH 96H 02/0000Z 45.8N 45.9W 70 KT 80 MPH...POST-TROP/EXTRATROP 120H 03/0000Z 52.0N 38.5W 55 KT 65 MPH...POST-TROP/EXTRATROP $$ Forecaster Cangialosi |
