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| #1241536 (Received by flhurricane at: 10:51 AM 15.Aug.2025) TCDAT5 Hurricane Erin Discussion Number 17 NWS National Hurricane Center Miami FL AL052025 1100 AM AST Fri Aug 15 2025 Erin has become better organized during the past several hours. The last few NOAA and Air Force Reserve aircraft passes through the cyclone have indicated the formation of an eyewall, with the Air Force Reserve aircraft reporting 700-mb flight-level winds of 75 kt northeast of the center. In addition, conventional satellite imagery shows the development of a central dense overcast, and a recently received WSFM microwave overpass shows a well-defined ring of shallow to moderate convection in the 37 GHz imagery. Based on these data, the initial intensity is increased to 65 kt and Erin becomes the first hurricane of the 2025 Atlantic Hurricane Season. The initial motion is 290/15. The subtropical ridge to the north will continue to steer Erin west-northwestward into the weekend. Encroaching mid-latitude westerly flow is forecast to cause a weakness to develop in the ridge during the latter part of the forecast period, and this will result in the hurricane gradually turning northwestward and northward by 120 h. The guidance remains in fairly good agreement through about 60-72 hours. After that time, there are some differences in both the forward speed and cross-track spread with the turn toward the north. The regional hurricane models again lie along the western edge of the guidance envelope, while the GFS and Google DeepMind models remain on the eastern edge. Although still spread, the guidance envelope has not shifted significantly since the last advisory, and the new track forecast is an update of the previous forecast. There is still uncertainty about what impacts Erin may bring to portions of the Bahamas, the east coast of the United States, and Bermuda in the long range. Erin is currently in a favorable environment for strengthening, although there are some uncertainties on whether dry air is entraining into the core. The improved low-level structure indicates potential for rapid strengthening, and based on this the first 36-48 h of the new intensity forecast shows a faster development rate. After 48 h, the hurricane is forecast to encounter some northerly to northwesterly vertical shear that should at least slow development. However, the global and regional hurricane models are in good agreement that Erin will become a powerful and increasingly large hurricane over the southwestern Atlantic over the weekend and into next week. It should be noted that the the Florida State SuperEnsemble and the US Navy COAMPS-TC models forecast higher peak intensities than the official forecast, so it would not be too surprising if Erin became stronger than currently forecast. KEY MESSAGES: 1. Heavy rainfall tonight through Sunday across the northern Leeward Islands, the Virgin Islands, and Puerto Rico may lead to isolated and locally considerable flash and urban flooding, along with landslides or mudslides. 2. Tropical storm conditions are possible for portions of the northern Leeward Islands, where Tropical Storm Watches are in effect, beginning on Saturday as the core of Erin passes north of those islands. Gusts to tropical storm force are possible in rainbands over portions of the Virgin Islands and Puerto Rico later in the weekend. 3. While the threat of direct impacts in the Bahamas and along the east coast of the United States appears to be gradually decreasing, there will still be a significant risk of dangerous surf and rip currents along western Atlantic beaches next week. 4. Interests in Bermuda should continue to monitor the progress of Erin since there is still a risk of strong winds, heavy rainfall, and high surf by the middle part of next week. FORECAST POSITIONS AND MAX WINDS INIT 15/1500Z 18.2N 56.1W 65 KT 75 MPH 12H 16/0000Z 18.9N 58.4W 75 KT 85 MPH 24H 16/1200Z 19.8N 61.4W 90 KT 105 MPH 36H 17/0000Z 20.6N 63.8W 105 KT 120 MPH 48H 17/1200Z 21.6N 66.0W 110 KT 125 MPH 60H 18/0000Z 22.7N 67.9W 115 KT 130 MPH 72H 18/1200Z 23.8N 69.2W 120 KT 140 MPH 96H 19/1200Z 26.5N 70.8W 115 KT 130 MPH 120H 20/1200Z 30.3N 71.0W 110 KT 125 MPH $$ Forecaster Beven |
