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| #1001555 (Received by flhurricane at: 4:45 AM 18.May.2020) TCDAT1 Tropical Storm Arthur Discussion Number 7 NWS National Hurricane Center Miami FL AL012020 500 AM EDT Mon May 18 2020 Arthur remains poorly organized in both satellite and radar imagery this morning, with the low-level center located near the southwestern edge of a complex of ragged convective bands. Surface observations from buoys off of the North Carolina coast suggest the central pressure has fallen a little since the last aircraft fix, so the intensity will be held at 40 kt for this advisory. The next aircraft is scheduled to reach Arthur between 11-12Z. Arthur`s forward speed has increased with the initial motion now 020/12. A baroclinic trough and associated surface front approaching from the west should cause Arthur to turn northeastward during the next several hours, with the forecast track showing the center passing near or just offshore of the North Carolina Outer Banks. By Tuesday and Tuesday night, Arthur will be entering the strong mid-latitude Westerlies, which will steer cyclone eastward for a day or two. After that time, Arthur or its remnants should turn southeastward and southward on the southwest side of a deep-layer trough over the central Atlantic. The latest guidance is showing a more southward motion after 60 h than seen previously, and the new forecast track is also nudged southward during that time. Arthur is moving near and almost parallel to the Gulf Stream, and the warm water could allow some strengthening before southwesterly shear increases significantly later today. The cyclone should merge with a frontal system and become extratropical in the 24-36 h period, with the global models indicating some increase in the winds north of the center as this occurs. The intensity forecast calls for Arthur to reach a 50 kt intensity in 36 h as an extratropical low in best agreement with the GFS model. After 48 h, the system should decay, and the global models suggest it should dissipate in the 96-120 h period. The new intensity forecast has only minor tweaks from the previous forecast. Key Messages: 1. A Tropical Storm Warning is in effect for a portion of the North Carolina coast. Tropical-storm-force winds and heavy rains are expected there today. 2. Dangerous coastal surf conditions and rip currents are expected to spread northward along the southeast U.S. coast to the mid-Atlantic states 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 18/0900Z 33.5N 76.6W 40 KT 45 MPH 12H 18/1800Z 35.2N 74.9W 45 KT 50 MPH 24H 19/0600Z 36.5N 72.1W 45 KT 50 MPH 36H 19/1800Z 36.5N 69.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 48H 20/0600Z 35.6N 66.5W 50 KT 60 MPH...POST-TROP/EXTRATROP 60H 20/1800Z 34.4N 65.1W 45 KT 50 MPH...POST-TROP/EXTRATROP 72H 21/0600Z 33.0N 64.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 96H 22/0600Z 31.0N 63.5W 25 KT 30 MPH...POST-TROP/EXTRATROP 120H 23/0600Z...DISSIPATED $$ Forecaster Beven |