Issued at 500 PM AST Tue Aug 12 2025
050 WTNT45 KNHC 122033 TCDAT5 Tropical Storm Erin Discussion Number 6 NWS National Hurricane Center Miami FL AL052025 500 PM AST Tue Aug 12 2025 Not much has changed with Erin's structure since this morning. A little bit of convection has formed over the low-level center, but overall the shower and thunderstorm activity remains limited. Due to the cyclone's fast motion, it is assumed that the maximum winds have not decreased, so the initial intensity is held at 40 kt. A quick south-of-due-west motion is expected to continue for the next 24 hours, with strong low- to mid-level ridging located to the north over the central and eastern Atlantic. Global models indicate that ridge is likely to weaken in a few days, which should cause Erin to begin moving west-northwestward in about 60 hours, with that motion continuing through day 5 (Sunday). In contrast to this morning, there were no major shifts in the latest track model simulations. The new NHC forecast has been placed along the southern part of the guidance envelope, lying closest to the HFIP Corrected Consensus (HCCA) and Google Deep Mind (GDM) models. This results in the new NHC track forecast having no appreciable difference from the morning forecast, with no additional shifting toward the northern Leeward Islands. Keep in mind that NHC track forecasts have an average error of 120-180 n mi (150-215 statute miles) at days 4 and 5, and future adjustments in the forecast are still possible. It may still take Erin a little bit of time to produce more significant deep convection while it continues to move over marginally warm sea surface temperatures and through an atmosphere of only modest instability and moisture. Sea surface temperatures and instability begin to increase after about 24 hours, which should allow Erin to produce more organized convection. Given that the cyclone already has a well-defined low-level structure, this could result in significant intensification toward the latter part of the forecast period, especially since the global models show an upper-level anticyclone building over the storm. The NHC intensity forecast is near the lower end of the guidance during the first few days of the forecast, but then falls in line closer to the consensus aids in 3-5 days. In this scenario, Erin would still become a major hurricane in about 4 or 5 days. KEY MESSAGES: 1. Erin could move close enough to the northern Leeward Islands, 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 12/2100Z 17.0N 38.3W 40 KT 45 MPH 12H 13/0600Z 16.6N 40.8W 40 KT 45 MPH 24H 13/1800Z 16.4N 43.9W 45 KT 50 MPH 36H 14/0600Z 16.6N 46.8W 50 KT 60 MPH 48H 14/1800Z 17.2N 49.9W 60 KT 70 MPH 60H 15/0600Z 17.9N 52.9W 75 KT 85 MPH 72H 15/1800Z 18.6N 56.0W 85 KT 100 MPH 96H 16/1800Z 20.0N 61.5W 95 KT 110 MPH 120H 17/1800Z 22.2N 65.7W 100 KT 115 MPH $$ Forecaster Berg