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| #1154034 (Received by flhurricane at: 5:17 PM 22.Sep.2023) TCDAT1 Tropical Storm Ophelia Discussion Number 6 NWS National Hurricane Center Miami FL AL162023 500 PM EDT Fri Sep 22 2023 The structure of the cyclone has undergone some noteworthy changes today. GOES-16 1-min visible imagery, along with data from the Air Force Hurricane Hunters and earlier scatterometer data, indicate that the center of the system has become better defined and is no longer attached to fronts. The satellite presentation has evolved as well, with the center becoming tucked under an area of deep convection this afternoon. The radius of maximum wind has contracted to around 50 to 60 n mi, further supporting its designation as Tropical Storm Ophelia earlier this afternoon. Aircraft data reveal that Ophelia has also strengthened, with the minimum pressure down to 986 mb and reduced flight-level and SFMR winds that support an initial intensity of 60 kt. Ophelia is moving north-northwestward (345/11 kt) within the flow between an upper-level trough over the southeastern U.S. and a ridge over the western Atlantic. This general motion should continue through Saturday while the center of Ophelia approaches North Carolina and moves inland within the warning area. Thereafter, a slight decrease in forward speed and a turn toward the north and north-northeast is forecast through the weekend. There was a slight westward shift in the near-term track guidance, and the updated NHC forecast has been nudged in that direction toward the latest multi-model consensus aids. The intensity forecast is more challenging given the unexpected strengthening trend observed today. Most of the intensity guidance shows little change in strength before landfall, although the global models show additional deepening of the low. However, some additional strengthening cannot be ruled out as Ophelia traverses the warm waters of the Gulf Stream on its approach to eastern North Carolina. While this does not seem like the most likely outcome and is not explicitly forecast, the increased risk warrants the issuance of a Hurricane Watch for a portion of the North Carolina coast from north of Surf City to Ocracoke Inlet. After landfall, the system is expected to quickly weaken due to the combination of land interaction, drier air, and strong upper-level winds. Ophelia is likely to become extratropical again in 36-48 h, with dissipation by 72 h as it becomes absorbed by a frontal boundary over the mid-Atlantic region. 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 today into 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 22/2100Z 32.9N 76.3W 60 KT 70 MPH 12H 23/0600Z 34.4N 76.8W 60 KT 70 MPH 24H 23/1800Z 36.1N 77.2W 45 KT 50 MPH...INLAND 36H 24/0600Z 37.6N 77.2W 30 KT 35 MPH...POST-TROP/EXTRATROP 48H 24/1800Z 38.9N 76.6W 25 KT 30 MPH...POST-TROP/EXTRATROP 60H 25/0600Z 39.9N 76.1W 25 KT 30 MPH...POST-TROP/EXTRATROP 72H 25/1800Z...DISSIPATED $$ Forecaster Reinhart |
