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| #1153986 (Received by flhurricane at: 10:56 AM 22.Sep.2023) TCDAT1 Potential Tropical Cyclone Sixteen Discussion Number 5 NWS National Hurricane Center Miami FL AL162023 1100 AM EDT Fri Sep 22 2023 Surface observations indicate the low pressure system off the southeast U.S. coast is deepening this morning. Recent pressure and wind data from NOAA buoy 41002 suggest the pressure has fallen to around 996 mb. While surface analyses indicate there is still a front in close proximity to the low, deep convection has become more concentrated to the north of the center. In fact, GOES-16 1-min visible imagery suggests the low-level center is re-forming closer to the convection. The broad wind field is asymmetric, with the strongest observed winds occurring to the north and west of the frontal feature. A NOAA Saildrone sampling the system reported a sustained wind of 40 kt and a gust around 50 kt earlier this morning. Based on the available observations, the initial intensity is held at 45 kt. An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate the system this afternoon. The initial motion of the cyclone is just west of due north (350/10 kt). The system is forecast to move north-northwestward to northward through Saturday along the west side of a subtropical ridge over the western and central Atlantic. This motion will take the center of the cyclone inland over eastern North Carolina on Saturday morning and over the Mid-Atlantic region Saturday night and Sunday. The track guidance is in good agreement for this forecast. Based on the slight northward adjustment to the initial position, the updated NHC forecast is slightly faster than the previous one, showing the cyclone center just inland in 24 h. Based on recent satellite and observational trends, the cyclone appears likely to strengthen during the next 12 h over the warm Gulf Stream waters. The more organized convective structure should also facilitate its transition to a tropical storm during the next 6-12 h as it starts to become separated from its frontal features and develops a smaller inner core. The near-term intensity forecast has been bumped up slightly (55 kt) before the system moves inland early Saturday. After landfall, the system is expected to weaken due to the negative influences of land interaction, drier air, and strong upper-level winds. This forecast shows extratropical transition by 48 h with dissipation by 72 h, in good agreement with the GFS and ECMWF models. 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. 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 flash, urban, and small stream 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 22/1500Z 32.3N 75.6W 45 KT 50 MPH...POTENTIAL TROP CYCLONE 12H 23/0000Z 33.2N 76.3W 55 KT 65 MPH...TROPICAL CYCLONE 24H 23/1200Z 34.9N 76.8W 50 KT 60 MPH...INLAND 36H 24/0000Z 36.8N 77.0W 40 KT 45 MPH...INLAND 48H 24/1200Z 38.3N 77.0W 30 KT 35 MPH...POST-TROP/EXTRATROP 60H 25/0000Z 39.3N 76.5W 25 KT 30 MPH...POST-TROP/EXTRATROP 72H 25/1200Z...DISSIPATED $$ Forecaster Reinhart |