Issued at 500 PM EDT Mon Sep 29 2025
000 WTNT44 KNHC 292053 TCDAT4 Tropical Storm Imelda Discussion Number 13 NWS National Hurricane Center Miami FL AL092025 500 PM EDT Mon Sep 29 2025 Since the prior advisory, Imelda's structure on satellite imagery continues to improve. Curved bands are now wrapping around the western side of the tropical storm's circulation, and the last few fixes from the NOAA and Air Force Reserve Hurricane Hunters did show enhanced winds wrapping around the western side, becoming more symmetric, though some northward tilt with height was still persisting on the last Tail Doppler Radar (TDR) swath from the NOAA-P3 aircraft. Satellite intensity estimates have continued to gradually rise since that time, so the initial intensity is being raised to 55 kt this advisory, in best agreement with the SAB subjective Dvorak fix of T3.5/55-kt and the latest SATCON intensity estimate of 54 kt. Imelda continues to move northward, estimated at 360/8 kt. This motion should continue through tonight, but as Humberto erodes the steering influence of a subtropical ridge east of Bermuda, the cyclone is expected to make a sharp turn to the east-northeast as the storm steering becomes dominated by the deep-layer trough that is digging southward upstream of Imelda. The latest track guidance trajectory is quite similar to the prior cycle, though it has once again shifted a bit faster beyond 36 h. There also remains a substantial amount of along-track spread in both the deterministic and ensemble guidance this afternoon. The NHC track forecast is a little faster than the prior cycle, once again attempting to blend the HCCA and Google DeepMind ensemble mean (GDMI). Based on the forecast track, tropical storm conditions are expected to begin on the Island of Bermuda in about 48 h, and in response, the Bermuda Weather Service has issued a Hurricane Watch for the island this advisory. Further intensification is expected over the next several days as Imelda remains in a low to moderate vertical wind shear environment along with sufficient mid-level moisture and warm sea-surface temperatures above 28 C. In 48-60 h, the shear starts quickly increasing, but a favorable trough interaction may temper this negative factor initially. This interaction may enhance the winds along the cyclone's western flank, as seen in the most recent set of hurricane-regional model runs. These enhanced winds may then evolve into a "sting jet" like feature as the system becomes extratropical in the 60-72 h time frame. The exact timing of this transition remains difficult to forecast, since the cyclone will still be under fairly warm SSTs at 60-72 h. The official intensity forecast is on the high side of the guidance envelope, but near the HCCA consensus aid. KEY MESSAGES: 1. Imelda is expected to intensify into a hurricane on Tuesday with the cyclone approaching Bermuda during the day Wednesday as a hurricane. A Hurricane Watch is now in effect for the island of Bermuda due to the expected onset of tropical storm conditions beginning Wednesday afternoon. 2. Tropical storm conditions are expected to continue for another few hours on Great Abaco and Grand Bahama island in the northwestern Bahamas. 2. Rainfall associated with Tropical Storm Imelda will continue to impact the Bahamas through tonight, which may produce flash and urban flooding. Locally heavy rainfall across the coastal Carolinas could cause isolated flash and urban flooding through tonight. 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 29/2100Z 27.7N 77.3W 55 KT 65 MPH 12H 30/0600Z 28.4N 76.8W 65 KT 75 MPH 24H 30/1800Z 29.3N 75.0W 70 KT 80 MPH 36H 01/0600Z 30.4N 72.2W 75 KT 85 MPH 48H 01/1800Z 31.7N 67.8W 80 KT 90 MPH 60H 02/0600Z 33.3N 62.3W 85 KT 100 MPH 72H 02/1800Z 35.0N 56.8W 75 KT 85 MPH...POST-TROP/EXTRATROP 96H 03/1800Z 39.0N 50.0W 55 KT 65 MPH...POST-TROP/EXTRATROP 120H 04/1800Z 43.7N 47.6W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Papin
