Issued at 1100 AM AST Tue Aug 12 2025
000 WTNT45 KNHC 121448 TCDAT5 Tropical Storm Erin Discussion Number 5 NWS National Hurricane Center Miami FL AL052025 1100 AM AST Tue Aug 12 2025 Erin still has a well-defined low-level circulation, but the convective pattern has degraded since overnight, with only a band of moderate convection located within the southern part of the circulation. A 1226 UTC ASCAT-C pass showed a maximum wind barb of 36 kt north of the center, and the intensity is held at a possibly generous 40 kt. Most likely, this is a result of Erin's fast motion, which has been south of due west (265 deg) at about 20 kt. The guidance suite indicates that Erin may continue to lose some latitude during the next 24 to 36 hours due to strong low- to mid-level ridging over the eastern and central Atlantic, but overall the general motion should be westward through early Thursday. After that time, indications are that the ridge may weaken over the western and central Atlantic, causing Erin to turn west-northwestward, but there are model discrepancies on when that might happen and where the break in the ridge actually forms. The trend has been for a weaker Erin in the short term and possibly a stronger ridge, and a number of track models, including HAFS-A and -B, HWRF, the European, HCCA, and the Google Deep Mind, have shifted south and west for much of the 5-day forecast. The NHC forecast has shifted in that direction accordingly, and it should be noted that a significant number of deterministic models and ensemble members still lie even farther south. The environment of marginal water temperatures (26-27 deg Celsius) and low atmospheric instability and moisture appear to remain nearly constant for the next 24 hours or so. Therefore, little to no intensification is expected through early Wednesday. The environment and water temperatures become much more suitable for strengthening by 48 hours, and since the cyclone already has a well-defined structure, it could become a hurricane by late Thursday. Continued strengthening is forecast after that time, and the NHC forecast continues to show Erin becoming a major hurricane by day 5 (early Sunday). There is quite a lot of spread in the intensity models, and the NHC prediction is in the upper regime of the envelope, close to the SHIPS model, Florida State Superensemble, and ICON intensity consensus. KEY MESSAGES: 1. Although it is still too early to know exactly what impacts Erin might bring to the northern Leeward Islands, the Virgin Islands, and Puerto Rico, the risk has increased for Erin to move closer to these islands over the weekend. Interests there should monitor the progress of this storm. 2. There is even greater uncertainty in what impacts, if any, might occur in portions of the Greater Antilles, the Bahamas, the east coast of the United States, and Bermuda next week. As we approach the climatological peak of the hurricane season, this is an opportune time to ensure your preparedness plans are in place. FORECAST POSITIONS AND MAX WINDS INIT 12/1500Z 17.2N 36.3W 40 KT 45 MPH 12H 13/0000Z 16.8N 39.1W 40 KT 45 MPH 24H 13/1200Z 16.5N 42.3W 40 KT 45 MPH 36H 14/0000Z 16.6N 45.2W 45 KT 50 MPH 48H 14/1200Z 17.1N 48.3W 55 KT 65 MPH 60H 15/0000Z 17.8N 51.3W 65 KT 75 MPH 72H 15/1200Z 18.5N 54.4W 75 KT 85 MPH 96H 16/1200Z 19.8N 60.3W 90 KT 105 MPH 120H 17/1200Z 21.4N 65.0W 100 KT 115 MPH $$ Forecaster Berg