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| #1001624 (Received by flhurricane at: 4:45 PM 18.May.2020) TCDAT1 Tropical Storm Arthur Discussion Number 9 NWS National Hurricane Center Miami FL AL012020 500 PM EDT Mon May 18 2020 Although the center of Arthur did not make landfall in the North Carolina Outer Banks, it passed within about 20 n mi southeast of Cape Hatteras around 1500 UTC. Tropical-storm-force wind gusts have been reported at several automated observing sites on and near the Outer Banks, with the highest sustained wind of 34 kt at Alligator River Bridge earlier this afternoon. Deep convection continues over the northeastern portion of Arthur`s circulation, but visible imagery has recently shown an increase in separation between low-level center and the convective activity. This is the result of increasing southwesterly shear and the beginning of the cyclone`s extratropical transition. The initial intensity remains 45 kt, which was in agreement with the earlier aircraft data. As the cyclone completes its extratropical transition, some strengthening is forecast due to baroclinic processes. After 24 hours, little change in strength is expected until the frontal gradients decrease on Wednesday. The system should gradually spin down after that time, and dissipate by late in the week. The initial motion estimate is 045/14 kt. Arthur should continue northeastward this evening, but is expected to turn eastward Tuesday morning as the cyclone becomes embedded within the mid-latitude westerlies. Troughing over the central and western Atlantic should cause the Arthur to turn southeastward on Wednesday when the steering flow becomes northwesterly. Little change was required to the previous NHC official forecast and the updated track again lies between the GFS, ECMWF, and the multi-model consensus. Dangerous coastal surf conditions and rip currents are expected to continue along portions of the mid-Atlantic and southeast U.S. coasts during the next couple of days. See products from your local National Weather Service Forecast Office for more details. FORECAST POSITIONS AND MAX WINDS INIT 18/2100Z 36.1N 73.9W 45 KT 50 MPH 12H 19/0600Z 36.9N 71.6W 50 KT 60 MPH 24H 19/1800Z 37.0N 68.7W 50 KT 60 MPH...POST-TROP/EXTRATROP 36H 20/0600Z 36.2N 66.8W 50 KT 60 MPH...POST-TROP/EXTRATROP 48H 20/1800Z 34.8N 65.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 60H 21/0600Z 33.0N 64.8W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 21/1800Z 31.5N 64.8W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 22/1800Z...DISSIPATED $$ Forecaster Brown |