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| #1246859 (Received by flhurricane at: 10:54 PM 01.Oct.2025) TCDAT4 Hurricane Imelda Discussion Number 22 NWS National Hurricane Center Miami FL AL092025 1100 PM AST Wed Oct 01 2025 Data from the Air Force Reserve reconnaissance aircraft this evening found that Imelda is likely in the early to mid stages of extratropical transition. In addition to the aircraft crossing a baroclinic zone just to the north of the hurricane's core, the winds have become very asymmetric, with hurricane-force winds around the western and southeastern sides of the circulation, but much lighter winds to the northeast. The aircraft also found rising pressure between fixes, and the earlier eyewall reported from the prior mission has been reduced to a small fragment on the northwestern side. Despite the degraded presentation, the 700 mb flight-level winds were a little higher than the prior mission, peaking at 98 kt in the southeastern quadrant. While this would normally translate to a somewhat higher 90 kt maximum sustained wind, these flight-level winds occurred where Imelda has little in the way of precipitation according to the Bermuda radar. Thus, the initial intensity will remain 85 kt for this advisory, using a slightly lower surface wind reduction. Aircraft fixes and Bermuda radar imagery indicate that Imelda continues to accelerate quickly to the east-northeast, with its estimated motion now at 075/25 kt. This motion will likely take the hurricane's inner eyewall fragment right over the island of Bermuda over the next couple of hours. The strongest winds associated with Imelda are likely to be felt just after the center passes by, thanks to the increasingly asymmetric wind-field of the hurricane. In fact, the global and hurricane-regional models show a distinct sting-jet like signature on the backside that both 18 UTC HAFS-A/B and the 12 UTC ECMWF show moving directly over Bermuda between now and the 06 UTC time frame. After passing Bermuda, the global and regional-hurricane models show the hurricane completing extratropical transition as the frontal boundary merges in with the cyclone's core. The NHC intensity forecast is a little lower than the prior advisory, but remains in good agreement with the consensus aids HCCA/IVCN. After Imelda clears Bermuda and becomes fully extratropical, the models are in better agreement about the cyclone turning northeastward by late Thursday or Friday when it fully phases with a digging shortwave trough located upstream of the system. While significant model spread persists, the 18 UTC GFS has come into better agreement with the other global model guidance showing this phasing solution rather than being left behind the trough. The latest NHC track forecast this evening is roughly a blend of the HFIP corrected consensus aid (HCCA) and the faster Google DeepMind ensemble mean (GDMI). KEY MESSAGES: 1. Imelda's core is currently near Bermuda and is expected to bring damaging hurricane-force winds and large and damaging waves to Bermuda as it moves over the island now into early Thursday. Significant hurricane-force gusts are likely across Bermuda even after the center passes. 2. Heavy rainfall could cause flash flooding across Bermuda tonight 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 and the western Atlantic during the next several days. FORECAST POSITIONS AND MAX WINDS INIT 02/0300Z 32.1N 65.0W 85 KT 100 MPH 12H 02/1200Z 32.8N 60.7W 80 KT 90 MPH...POST-TROP/EXTRATROP 24H 03/0000Z 34.0N 55.0W 65 KT 75 MPH...POST-TROP/EXTRATROP 36H 03/1200Z 36.2N 51.3W 60 KT 70 MPH...POST-TROP/EXTRATROP 48H 04/0000Z 38.6N 49.4W 55 KT 65 MPH...POST-TROP/EXTRATROP 60H 04/1200Z 41.4N 47.3W 50 KT 60 MPH...POST-TROP/EXTRATROP 72H 05/0000Z 44.5N 43.7W 45 KT 50 MPH...POST-TROP/EXTRATROP 96H 06/0000Z 49.5N 34.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 07/0000Z 51.2N 28.0W 40 KT 45 MPH...POST-TROP/EXTRATROP $$ Forecaster Papin |
