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| #1246495 (Received by flhurricane at: 4:57 AM 29.Sep.2025) TCDAT4 Tropical Storm Imelda Discussion Number 11 NWS National Hurricane Center Miami FL AL092025 500 AM EDT Mon Sep 29 2025 Imelda continues to slowly become better organized. Earlier aircraft data indicated that the pressure has fallen to 996 mb, and satellite imagery shows persistent convection near and north of the center. The initial intensity is set to 40 kt with numerous 35 kt wind vectors on the evening scatterometer pass and higher Dvorak estimates. The storm is progressing northward at about 7 kt. This motion is forecast to continue today due to steering along the western side of the subtropical ridge. Humberto is forecast to erode the ridge by Tuesday, causing an abrupt turn of Imelda to the east-northeast with some acceleration as the cyclone encounters faster mid- latitude flow. There is increasing confidence in the storm staying well offshore of the southeastern United States coast. The latest track guidance is similar to the previous cycle, although faster at the end, and remains close to Bermuda. The medium range forecast beyond Bermuda is quite uncertain with a complicated flow pattern due to a digging north Atlantic trough and then-extratropical Humberto interactions. Imelda is forecast to gradually strengthen within an environment of moderate south-southwesterly vertical wind shear, warm ocean waters and within a fairly moist mid-level air mass for the next couple of days. Thereafter, an upper-level trough will help to initiate extratropical transition, and some of the models are showing this as a favorable trough interaction, causing a larger and stronger cyclone. The GFS and ECMWF models are also showing a sting jet developing as well about the time that Imelda is near Bermuda, so that situation will have to be watched closely. The official forecast remains at the higher end of the model guidance. Most of the global models are showing a faster extratropical transition after Imelda moves past Bermuda, and that is indicated in the new NHC forecast. KEY MESSAGES: 1. Imelda is expected to continue to bring tropical storm conditions to portions of the northwestern Bahamas today. 2. Rainfall associated with Imelda will continue to impact eastern Cuba and the Bahamas through Tuesday, which will likely produce flash and urban flooding. Mudslides are possible in the higher terrain. Heavy rainfall across the coastal Carolinas could cause isolated flash and urban flooding through Tuesday. 3. Interests in Bermuda should monitor the progress of Imelda as a Hurricane Watch could be required late today. 4. Swells and high surf from both Humberto and Imelda are expected to produce dangerous marine conditions and rip currents along the east coast of Florida and the Georgia coast today. These conditions are expected to spread northward along much of the east coast of the United States early this week. FORECAST POSITIONS AND MAX WINDS INIT 29/0900Z 25.5N 77.1W 40 KT 45 MPH 12H 29/1800Z 26.7N 77.1W 50 KT 60 MPH 24H 30/0600Z 28.1N 76.8W 60 KT 70 MPH 36H 30/1800Z 28.9N 75.1W 65 KT 75 MPH 48H 01/0600Z 29.9N 72.3W 70 KT 80 MPH 60H 01/1800Z 31.1N 68.8W 75 KT 85 MPH 72H 02/0600Z 32.4N 63.8W 80 KT 90 MPH 96H 03/0600Z 35.0N 56.0W 70 KT 80 MPH...POST-TROP/EXTRATROP 120H 04/0600Z 39.5N 52.5W 60 KT 70 MPH...POST-TROP/EXTRATROP $$ Forecaster Blake |
