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| #1246790 (Received by flhurricane at: 11:00 AM 01.Oct.2025) TCDAT4 Hurricane Imelda Discussion Number 20 NWS National Hurricane Center Miami FL AL092025 1100 AM EDT Wed Oct 01 2025 The Air Force Hurricane Hunters investigating Imelda this morning have found that the hurricane is strengthening. They reported a closed, circular eyewall during their two passes through the storm, and dropsonde data indicate the central pressure has fallen to around 966 mb. The aircraft measured peak 700-mb flight-level winds of 97 kt in the southeastern quadrant of Imelda, which supports raising the initial intensity to 85 kt for this advisory. Imelda is moving quickly east-northeastward (065/17 kt) within the flow ahead of a western Atlantic deep-layer trough. In the near term, the track models agree that the core of Imelda will move near or over Bermuda tonight into early Thursday, with conditions there expected to deteriorate later today. Once Imelda passes Bermuda and becomes extratropical, the forecast becomes much more uncertain given the significant spread in the track guidance and ensembles. In general, most global models show the extratropical low becoming captured by the upper trough, which results in a northeastward motion across the north Atlantic through the 5-day period. The outlying GFS solution shows the trough missing the low, and as a result the GFS is almost 1500 miles away from the ECMWF at day 5. Once again, the long-range NHC forecast is weighted more heavily toward a consensus of the ECMWF and Google Deep Mind solutions. The improved inner core structure of the hurricane and the potential for positive trough interaction could support some additional strengthening before Imelda reaches Bermuda, despite increasing southwesterly shear expected over the hurricane. This is reflected in the updated NHC intensity forecast, which lies on the high end of the guidance envelope. Extratropical transition is now forecast in 24 h, after which some gradual weakening is predicted. However, Imelda will remain a powerful extratropical cyclone for much of the forecast period as its wind field expands while the cyclone moves deeper into the mid-latitudes. As a result, large swell and dangerous marine and rip current conditions will continue to affect much of the central and western Atlantic for the next several days. KEY MESSAGES: 1. Imelda is expected to bring damaging hurricane-force winds and large and damaging waves to Bermuda when it passes near or over the island tonight. Preparations to protect life and property should be rushed to completion, as tropical storm conditions are expected to spread across the region beginning later today. 2. Heavy rainfall could cause flash flooding across Bermuda later today into Thursday. 3. Swells and high surf from 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 01/1500Z 31.0N 70.4W 85 KT 100 MPH 12H 02/0000Z 31.9N 66.7W 90 KT 105 MPH 24H 02/1200Z 32.6N 61.5W 85 KT 100 MPH...POST-TROP/EXTRATROP 36H 03/0000Z 33.8N 56.2W 75 KT 85 MPH...POST-TROP/EXTRATROP 48H 03/1200Z 35.8N 52.4W 65 KT 75 MPH...POST-TROP/EXTRATROP 60H 04/0000Z 38.0N 50.0W 60 KT 70 MPH...POST-TROP/EXTRATROP 72H 04/1200Z 40.7N 48.2W 55 KT 65 MPH...POST-TROP/EXTRATROP 96H 05/1200Z 45.9N 40.4W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 06/1200Z 50.0N 32.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Reinhart |
