Issued at 500 AM AST Sun Aug 17 2025
251 WTNT45 KNHC 170842 TCDAT5 Hurricane Erin Discussion Number 24 NWS National Hurricane Center Miami FL AL052025 500 AM AST Sun Aug 17 2025 Satellite and Doppler Radar data from San Juan indicate that Erin is going through some notable structural changes. The hurricane still has a small eye in radar images with a tight and closed eyewall. Beyond the small core, there are numerous convective rainbands that are expanding in all quadrants, with some indication of an outer eyewall beginning to take shape. Data from the Air Force Hurricane Hunters a few hours ago indicated that the peak winds have been decreasing, and the initial intensity is set at 110 kt using a blend of the latest satellite estimates. The outer bands to the south of the center are still affecting portions of the Virgin Islands, Puerto Rico, and the Dominican Republic. These bands are producing gusty winds and locally heavy rains. The Air Force and NOAA Hurricane Hunters are scheduled to investigate Erin again later this morning, and their data will provide a better assessment of the hurricane's intensity and structure. Erin has been wobbling around, but it appears to be moving a little to the south of the previous track. The hurricane is still moving west-northwestward at 12 kt on the south side of a subtropical ridge. This ridge is expected to break down later today due to a series of troughs moving across the northwestern Atlantic. In response to the pattern change, Erin should gradually turn toward the north and eventually the northeast. This motion should take the core of Erin to the east of the Bahamas on Monday and then roughly midway between Bermuda and the east coast of the U.S. around the middle of the week. The NHC track forecast has been nudged to the west in the short term based on the initial motion and latest model guidance. The quick weakening over the past 6 to 12 hours is associated with Erin's structural changes and not environmental conditions. Since the large-scale environment is expected to be favorable for about another day, re-strengthening is possible during that time period. However, it should be noted that predicting the intensity evolution from internal dynamics are challenging, and models often provide little reliability in their solutions. Beyond 24 to 36 hours, a broadening of the wind field and some increase in shear should cause a gradual decay in the peak winds. Regardless of the details, there is high confidence that Erin will remain a powerful hurricane during the next several days. Erin is growing in size, and that trend is expected to continue over the next few days. The expanding wind field will result in rough ocean conditions over much of the western Atlantic. Given the track adjustments and increasing size, the government of the Bahamas has issued a Tropical Storm Warning for the Turks and Caicos Islands and a Tropical Storm Watch for the Southeast Bahamas. KEY MESSAGES: 1. Heavy rainfall is expected to continue across the Virgin Islands and Puerto Rico today. Locally considerable flash and urban flooding, along with landslides or mudslides, are possible. 2. Tropical storm conditions are expected in the Turks and Caicos Islands and are possible in the Southeast Bahamas tonight and Monday. Gusts to tropical storm force are possible in Erin's outer rainbands in portions of Puerto Rico today and the central Bahamas on Monday and Tuesday. 3. Erin is expected to produce life-threatening surf and rip currents along the beaches of the Bahamas, much of the east coast of the U.S., Bermuda, and Atlantic Canada during the next several days. 4. Interests along the North Carolina and Mid-Atlantic coasts, and Bermuda should monitor the progress of Erin as there is a risk of strong winds associated with the outer rainbands during the middle part of the week. FORECAST POSITIONS AND MAX WINDS INIT 17/0900Z 20.6N 66.4W 110 KT 125 MPH 12H 17/1800Z 21.3N 67.9W 115 KT 130 MPH 24H 18/0600Z 22.5N 69.5W 125 KT 145 MPH 36H 18/1800Z 23.8N 70.6W 120 KT 140 MPH 48H 19/0600Z 25.2N 71.5W 115 KT 130 MPH 60H 19/1800Z 26.9N 72.1W 110 KT 125 MPH 72H 20/0600Z 28.9N 72.2W 105 KT 120 MPH 96H 21/0600Z 33.3N 70.2W 95 KT 110 MPH 120H 22/0600Z 38.6N 63.2W 85 KT 100 MPH $$ Forecaster Cangialosi