Issued at 1100 PM EDT Mon Sep 29 2025
446 WTNT44 KNHC 300248 TCDAT4 Tropical Storm Imelda Discussion Number 14 NWS National Hurricane Center Miami FL AL092025 1100 PM EDT Mon Sep 29 2025 Satellite imagery and reports from an Air Force Reserve Hurricane Hunter aircraft indicate that Imelda has lost some organization since the last advisory. The aircraft data shows a broad center with a radius of maximum winds of at least 35 n mi, and the satellite imagery currently shows no organized convection near the aircraft-reported center. In addition, satellite fixes from TAFB and SAB were well to the northeast of the aircraft position, suggesting the vortex has a significant vertical tilt. Despite the ragged structure, the aircraft-reported winds support keeping an initial intensity of 55 kt. The initial motion is now 010/7 kt. A turn toward the northeast is expected tonight, followed by a turn toward the east-northeast and a faster forward speed. This change is due partly to Hurricane Humberto eroding the steering influence of a subtropical ridge east of Bermuda, and partly due to a deep-layer trough that is digging southward to the north and northwest of Imelda. The track guidance overall is a bit slower than earlier, and based on this the new forecast track is a little slower than the previous track. The new forecast track indicates that tropical storm conditions are expected to begin on the island of Bermuda in 36-48 h. Imelda is currently in an upper-level wind environment that has moderate shear, but is strongly divergent, and this is forecast to continue for the next 36-48 h. This should allow some strengthening. However, the current state of the storm is not conducive, and thus the new intensity forecast calls for slower strengthening than the previous forecast. In 48-60 h, the shear increases, and interaction with the deep-layer trough will likely start the extratropical transition process. This should be complete by 72 h. While there may be "sting jet" winds during the transition as mentioned in the previous discussion, the guidance is in good agreement that the system should steadily decay after the transition is complete. Overall, the new intensity forecast is a little weaker compared to the previous forecast. KEY MESSAGES: 1. Imelda is expected to intensify into a hurricane Tuesday or Tuesday night with the cyclone approaching Bermuda during the day Wednesday as a hurricane. A Hurricane Watch is in effect for the island of Bermuda due to the expected onset of tropical storm conditions beginning Wednesday afternoon. 2. Locally heavy rainfall across coastal sections of southeast North Carolina could cause isolated flash and urban flooding through tonight. As Imelda passes near Bermuda, 2 to 4 inches – 50 to 100 mm – of rainfall is expected from Wednesday into Thursday. 3. Swells and high surf from both Humberto and Imelda are expected to produce dangerous marine conditions and rip currents along much of the East Coast of the United States during the next several days. FORECAST POSITIONS AND MAX WINDS INIT 30/0300Z 28.4N 77.2W 55 KT 65 MPH 12H 30/1200Z 29.2N 76.3W 60 KT 70 MPH 24H 01/0000Z 30.1N 74.1W 65 KT 75 MPH 36H 01/1200Z 31.1N 70.7W 75 KT 85 MPH 48H 02/0000Z 32.4N 66.0W 80 KT 90 MPH 60H 02/1200Z 33.8N 60.7W 75 KT 85 MPH 72H 03/0000Z 35.2N 55.7W 65 KT 75 MPH...POST-TROP/EXTRATROP 96H 04/0000Z 39.4N 50.3W 55 KT 65 MPH...POST-TROP/EXTRATROP 120H 05/0000Z 43.1N 46.6W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Beven
