Issued at 1100 AM AST Wed Aug 13 2025
000 WTNT45 KNHC 131435 TCDAT5 Tropical Storm Erin Discussion Number 9 NWS National Hurricane Center Miami FL AL052025 1100 AM AST Wed Aug 13 2025 Erin continues to have a ragged overall appearance, with one burst of convection just southwest of the center and skeletal convective bands elsewhere in the northwestern semicircle. Various subjective and objective satellite intensity estimates are in the 30-45 kt range, and these have changed little over the past several hours. A just-received scatterometer overpass shows winds near 40 kt just north of the center, and based on these data the initial intensity is held at 40 kt. Erin continues to struggle to intensify, likely due to its track over persistent sea surface temperatures of 26-27C and entrainment of dry and stable air. The forecast track keeps the system over these marginal SSTs for another 24 h or so, followed by a motion over increasing SSTs that reach 29-30C by the end of the forecast period. The cyclone is currently in a favorable low- to moderate-shear environment, and this is likely to continue for the next 72 h. This evolution should allow Erin to significantly intensify, with the cyclone forecast to become a hurricane by 48 h and a major hurricane by 96 hr. After 72-96 h, Erin may encounter increased northerly shear as it tracks to the northeast of a large upper-level anticyclone forecast to form near Hispaniola and the southeastern Bahamas. Although the strength of shear the cyclone will encounter is uncertain, the intensity guidance suggests a lower rate of intensification at that time. The new intensity forecast is little changed from the previous forecast and is in best agreement with the intensity consensus. The initial motion is now 265/15 kt. While a strong low- to mid-level ridge currently is situated to the north of Erin, in a day or two a slight weakness is forecast to develop in this ridge near 65W longitude. This should cause the tropical cyclone to turn west-northwestward after 24 h, with some decrease in forward speed after 72 h. After 96 h, a developing break in the ridge near the southeastern coast of the United States should lead to a northwestward motion. The track guidance is in fairly good agreement, and the official forecast on the southern side of the guidance envelope between the HCCA corrected consensus and the other consensus models. The new track is similar to the previous track through 72 h and a little west of the previous track thereafter. Users are reminded that NHC track forecasts have an average error of 150 to 215 miles at days 4 and 5, and future adjustments to the forecast are still possible. KEY MESSAGES: 1. Erin could move close enough to the northern Leeward Islands, the Virgin Islands, and Puerto Rico over the weekend to produce some impacts on those islands. However, the magnitude of those impacts is still not known, and interests there should continue to monitor the progress of this storm. 2. There is even greater uncertainty in what impacts 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 13/1500Z 16.3N 43.4W 40 KT 45 MPH 12H 14/0000Z 16.3N 45.6W 45 KT 50 MPH 24H 14/1200Z 16.6N 48.6W 50 KT 60 MPH 36H 15/0000Z 17.4N 51.5W 55 KT 65 MPH 48H 15/1200Z 18.2N 54.3W 65 KT 75 MPH 60H 16/0000Z 19.0N 57.2W 75 KT 85 MPH 72H 16/1200Z 19.9N 60.0W 85 KT 100 MPH 96H 17/1200Z 21.7N 64.6W 100 KT 115 MPH 120H 18/1200Z 23.9N 67.3W 105 KT 120 MPH $$ Forecaster Beven