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| #1150073 (Received by flhurricane at: 10:59 AM 29.Aug.2023) TCDAT3 Hurricane Franklin Discussion Number 36 NWS National Hurricane Center Miami FL AL082023 1100 AM EDT Tue Aug 29 2023 Visible, infrared, and microwave satellite imagery indicates that Franklin is undergoing an eyewall replacement cycle with an outer concentric band becoming more dominant. The inner eyewall has become a little more ragged, and has started to collapse on the northern side. A 1137z 91GHz/37GHz SSMIS microwave pass confirmed the outer eyewall is becoming more dominant as well. The subjective and objective Dvorak estimates were in fairly good agreement this cycle, with a data-T of 5.5 and Final-T of 6.0 from both TAFB and UW-CIMSS ADT. Given the ongoing inner structural changes and the slightly weaker appearance on satellite, the initial intensity for this advisory lowered to 115 kt for this advisory. Franklin is moving north-northeastward at around 10 kt. A more northeastward motion is expected later today as the hurricane rounds the edge of the subtropical ridge and gets caught in the southwesterly flow ahead of a mid-latitude trough moving off the northeast U.S. coast and Atlantic Canada. There still remains a good amount of spread in the track guidance envelope with the GFS faster and further north, and the ECMWF slower and further south. The NHC track lies in the middle of the guidance, near the consensus aids TVCA and HCCA. Even though the center of Franklin is forecast to pass to the northwest of Bermuda on Wednesday, tropical-storm-force winds associated with the hurricane are expected to extend well to the southeast of the center. The intensity forecast remains similar to the previous forecast. Franklin is expected to continue weakening, as it begins to move northward over cooler waters. ECMWF and GFS SHIPS guidance also forecast the vertical wind shear to increase over the hurricane in about 36 h. The current NHC forecast has Franklin becoming extratropical in 4 days. There is some guidance, including the GFS, that have this transition occurring a little faster, while the ECMWF is a little slower with this transition. KEY MESSAGES: 1. Tropical storm conditions are expected 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 east coast of the United States. These conditions are expected to continue during the next several days. FORECAST POSITIONS AND MAX WINDS INIT 29/1500Z 30.8N 70.4W 115 KT 130 MPH 12H 30/0000Z 32.0N 69.6W 110 KT 125 MPH 24H 30/1200Z 33.7N 67.7W 100 KT 115 MPH 36H 31/0000Z 35.3N 64.8W 95 KT 110 MPH 48H 31/1200Z 36.9N 60.8W 90 KT 105 MPH 60H 01/0000Z 39.0N 55.7W 80 KT 90 MPH 72H 01/1200Z 41.3N 50.6W 75 KT 85 MPH 96H 02/1200Z 46.9N 42.9W 65 KT 75 MPH...POST-TROP/EXTRATROP 120H 03/1200Z 53.6N 34.4W 50 KT 60 MPH...POST-TROP/EXTRATROP $$ Forecaster Kelly/Brown |
