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Hurricane Teddy Forecast Discussion Number 39
2020-09-22 04:48:25| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Mon Sep 21 2020 000 WTNT45 KNHC 220248 TCDAT5 Hurricane Teddy Discussion Number 39 NWS National Hurricane Center Miami FL AL202020 1100 PM AST Mon Sep 21 2020 Air Force Reserve hurricane hunter found Teddy a little stronger this evening. Flight level peak wind was 111 kt in the east quadrant and the highest observed SFMR wind was 69 kt. A blend of these data yields an initial intensity of 85 kt for this advisory. Teddy is accelerating toward the north in response to a mid- to upper tropospheric mid-latitude trough approaching from the northwest. Dynamic forcing produced by the aforementioned baroclinic system and warm (27-28C) waters associated with the Gulf Stream could induce a short period of strengthening during the next few hours, or so. Through the remaining portion of the forecast period, Teddy will traverse cooler oceanic temperatures north of the Gulf Stream and lose its baroclinic support inducing a gradual weakening trend as the post-tropical cyclone quickly moves over eastern Nova Scotia, the Gulf of St. Lawrence and Newfoundland. After that time, Teddy should become absorbed by a larger non-tropical, high latitude low pressure system. There still remains much uncertainty as to whether or not Teddy will complete its extratropical transition prior to reaching Nova Scotia. The global models show the cyclone merged or embedded in the baroclinic zone, but the associated simulated infrared presentation shows Teddy maintaining a rather small warm, inner core. Regardless of it classification during that time, high winds, heavy rain, storm surge and destructive waves are still predicted for the south coast of Nova Scotia. Teddy's horizontal wind profile is forecast to nearly double during the next couple of days as it moves northward and interacts with the aforementioned baroclinic system. Gale-force winds are likely along portions of the near shore waters of the northeast United States. The forecast wind radii at the 24 hour period and beyond are based on the RVCN Wind Radii Consensus model that consists of a bias-corrected average of the global and regional models. Please see products from your local office for more information about marine hazards, including extremely dangerous rip currents expected over much of the western Atlantic beaches. Key Messages: 1. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada late Tuesday through Thursday, where direct impacts from wind, rain, and storm surge are expected. Tropical Storm Watches and Warnings are in effect for portions of Nova Scotia, Prince Edward Island and Newfoundland. 2. Very large swells produced by Teddy are expected to affect portions of Bermuda, the Leeward Islands, the Greater Antilles, the Bahamas, the east coast of the United States, and Atlantic Canada during the next few days. These swells are expected to cause life-threatening surf and rip current conditions. 3. Heavy rainfall across Atlantic Canada is expected with Teddy between Tuesday and Thursday after it becomes a strong post-tropical cyclone. FORECAST POSITIONS AND MAX WINDS INIT 22/0300Z 35.6N 61.5W 85 KT 100 MPH 12H 22/1200Z 38.4N 62.6W 85 KT 100 MPH 24H 23/0000Z 41.1N 63.1W 70 KT 80 MPH 36H 23/1200Z 44.6N 61.5W 60 KT 70 MPH 48H 24/0000Z 49.0N 58.7W 50 KT 60 MPH...POST-TROP/EXTRATROP 60H 24/1200Z 52.8N 54.8W 45 KT 50 MPH...POST-TROP/EXTRATROP 72H 25/0000Z 58.1N 51.4W 40 KT 45 MPH...POST-TROP/EXTRATROP 96H 26/0000Z...DISSIPATED $$ Forecaster Roberts
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