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| #1154072 (Received by flhurricane at: 10:50 PM 22.Sep.2023) TCDAT1 Tropical Storm Ophelia Discussion Number 7 NWS National Hurricane Center Miami FL AL162023 1100 PM EDT Fri Sep 22 2023 Recent WSR-88D radar data from Wilmington and Morehead City, North Carolina, show convection wrapping around Ophelia`s center, which is also embedded beneath a convective canopy in satellite imagery. Soon after the previous advisory, the Air Force Reserve Hurricane Hunters measured SFMR winds to hurricane force west of the center within the deep convection, however those winds were not measured again on their final pass through that area. Radar imagery and microwave data from that period showed that a mid-level eye feature had been forming well to the west of the surface center, but that feature has since dissipated, suggesting that it--and the hurricane-force winds--may have been a transient occurrence. Regardless, the SFMR and flight-level winds were strong enough to support an intensity of 60 kt, and that remains the estimated intensity right now. Another Hurricane Hunter aircraft is scheduled to investigate Ophelia in a couple of hours and should provide a final estimate of the intensity before the storm reaches land. The current motion is north-northwestward (330 degrees) at 10 kt. Ophelia is moving around the western periphery of the subtropical ridge and is therefore expected to turn northward and then northeastward during the next couple of days. This track will take Ophelia`s center inland over North Carolina on Saturday, and then across portions of southeastern Virginia and the Delmarva Peninsula Saturday night and Sunday. An additional westward shift was made to the first 24 hours of the official track forecast, mainly due to Ophelia`s center being tugged westward by the deep convection earlier this afternoon. Ophelia`s center is only expected to be over the warm waters of the Gulf Stream for another 6 hours or so before moving inland, so the window for strengthening is beginning to close. It should be stressed, however, that there is very little difference if Ophelia reaches land as a 60-kt tropical storm or a 65-kt hurricane. Weakening is expected once the center moves inland Saturday morning, and the intensity guidance is in fairly good agreement that the winds should drop below tropical storm force between 24 and 36 hours while Ophelia is over southeastern Virginia. The system is forecast to become extratropical by 36 hours, although the latest phase-space diagrams and simulated satellite imagery suggest this transition could happen as soon as 24 hours. The extratropical low is forecast to dissipate by 60 hours near the Delmarva Peninsula when it becomes absorbed within its associated frontal zone. Key Messages: 1. Tropical storm conditions are expected along portions of the southeastern and mid-Atlantic U.S. coasts within the Tropical Storm Warning area through Saturday night. Hurricane conditions are possible within the Hurricane Watch area early Saturday. 2. There is a danger of life-threatening storm surge inundation over portions of eastern North Carolina and southeastern Virginia, including Pamlico and Albemarle Sounds, the Neuse and Pamlico Rivers, the lower James River, and the lower Chesapeake Bay, where Storm Surge Warnings are in place. Residents in these areas should follow advice given by local officials. 3. Heavy rainfall from this system could produce locally considerable flash, and urban flooding impacts across portions of the Mid-Atlantic states from North Carolina to New Jersey through Sunday. 4. Swells generated by this system will affect much of the U.S. east coast through the weekend, likely causing life-threatening surf and rip currents. FORECAST POSITIONS AND MAX WINDS INIT 23/0300Z 33.6N 76.8W 60 KT 70 MPH 12H 23/1200Z 35.0N 77.3W 50 KT 60 MPH...INLAND 24H 24/0000Z 36.6N 77.5W 40 KT 45 MPH...INLAND 36H 24/1200Z 38.0N 77.0W 30 KT 35 MPH...POST-TROP/EXTRATROP 48H 25/0000Z 39.0N 76.1W 25 KT 30 MPH...POST-TROP/EXTRATROP 60H 25/1200Z...DISSIPATED $$ Forecaster Berg |
