Issued at 500 AM EDT Tue Aug 19 2025
852 WTNT45 KNHC 190856 TCDAT5 Hurricane Erin Discussion Number 32 NWS National Hurricane Center Miami FL AL052025 500 AM EDT Tue Aug 19 2025 Moderate to strong northwesterly shear has caused Erin's structure to become more asymmetric, with dry air infiltrating into the northwestern part of the circulation, and a long trailing convective band still draped to the south over the Turks and Caicos Islands. An earlier Air Force Reserve Hurricane Hunter mission made a final pass through the center of Erin around 1230 am and measured flight-level winds of 97 kt, with a central pressure up to 953 mb. Combining this information with the latest satellite estimates, Erin's intensity is set at 100 kt, which could be a bit generous. Erin has been moving slowly northwestward since yesterday, with an initial motion estimated to be 325/6 kt. There is not much change to the track forecast reasoning, with the hurricane still expected to recurve over the western Atlantic between the U.S. east coast and Bermuda over the next 3-4 days. The main highlight of the new forecast is that much of the track guidance, including the consensus aids, have shifted slightly west of the previous NHC prediction during the first 2-3 days. The new NHC forecast is very close to the TVCA and HCCA consensus aids during the first 48 hours, and then closer to the TVCA aid beyond 48 hours. It should be noted that there is still some space for additional adjustments to the track forecast, particularly beyond 48 hours with the HCCA aid lying along the northwestern edge of the guidance envelope. There are mixed signals on Erin's future intensity. On one hand, more favorable environmental shear and upper-level divergence in 24-36 hours should support some re-intensification. On the other hand, Erin's slow motion and large size could lead to some upwelling of cooler water, and the hurricane's broad structure could limit significant strengthening. The official forecast only shows fluctuations in intensity for the next 3 days, although it's becoming more likely that Erin could just weaken very gradually during that time. Erin is forecast to maintain hurricane strength for the next 5 days, but it is likely to begin interacting with a frontal boundary by Friday and become extratropical by late Saturday. The more important part of the forecast is that model guidance has continued to show Erin growing in size, and the wind radii have been made larger in the new NHC forecast. This new forecast now brings tropical-storm-force winds very close to the Mid-Atlantic and southern New England coast later this week. Erin's expanding wind field will result in rough ocean conditions over much of the western Atlantic. It should be noted that the 34- and 50-kt wind speed probabilities beyond 36 hours in the text and graphical products are likely underestimating the risk of those winds occurring. This is because the forecast wind field of Erin is considerably larger than average compared to the wind field used to derive the wind speed probability product. KEY MESSAGES: 1. 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. Beachgoers in those areas should follow advice from lifeguards, local authorities, and beach warning flags. 2. Tropical storm conditions and coastal flooding are possible in the North Carolina Outer Banks beginning late Wednesday or Wednesday night where Tropical Storm and Storm Surge Watches are in effect. Interests in along the U.S. Mid-Atlantic and southern New England coasts and on Bermuda should also monitor the progress of Erin as strong winds are possible Thursday and Friday. 3. Heavy rainfall from the outer bands of Erin will continue today for the Turks and Caicos and through tonight for the Bahamas. Flash and urban flooding are possible. 4. Tropical storm conditions are expected in the Turks and Caicos Islands and in the southeast Bahamas for a few more hours. Tropical storm conditions are possible in portions of the central Bahamas today. FORECAST POSITIONS AND MAX WINDS INIT 19/0900Z 24.8N 72.0W 100 KT 115 MPH 12H 19/1800Z 26.1N 72.7W 95 KT 110 MPH 24H 20/0600Z 28.1N 73.5W 95 KT 110 MPH 36H 20/1800Z 30.3N 74.0W 100 KT 115 MPH 48H 21/0600Z 32.6N 73.4W 100 KT 115 MPH 60H 21/1800Z 34.6N 71.4W 95 KT 110 MPH 72H 22/0600Z 36.5N 68.4W 90 KT 105 MPH 96H 23/0600Z 39.5N 61.0W 75 KT 85 MPH 120H 24/0600Z 42.0N 53.4W 65 KT 75 MPH...POST-TROP/EXTRATROP $$ Forecaster Berg