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| #1018329 (Received by flhurricane at: 4:56 AM 22.Sep.2020) TCDAT5 Hurricane Teddy Discussion Number 40 NWS National Hurricane Center Miami FL AL202020 500 AM AST Tue Sep 22 2020 Recent satellite imagery shows that the central convection is diminishing, with a comma-like cloud pattern developing. The current intensity is held at 85 kt based on continuity from the earlier aircraft mission. Another Hurricane Hunter aircraft is scheduled to investigate Teddy later today which should provide a good estimate of the intensity. Teddy is moving along the northern part of the Gulf Stream and should begin to move into cooler waters later today. Therefore weakening is expected over the next couple of days. However, baroclinic forcing should keep the cyclone at or near hurricane strength while it approaches Nova Scotia. The official intensity forecast is above the model consensus to qualitatively account for baroclinic effects. After 72 hours, or sooner, post-tropical Teddy should become absorbed or merge with a large extratropical low over the north Atlantic. Teddy has accelerated somewhat and is now moving north-northeastward near 24 kt. The hurricane is moving on the eastern side of a mid-tropospheric cyclone centered off the northeastern U.S. coast. Teddy should continue its north-northwestward motion today and then turn north-northeastward as the mid-tropospheric cyclone shifts northeastward. This will take post-tropical Teddy over Nova Scotia and near Newfoundland during the next couple of days. The official forecast is close to the corrected dynamical model consensus, or HFIP, and similar to the previous NHC track. The wind field of Teddy should continue to expand today and tonight, and the extent of 12-ft seas is also growing. See the Key Message regarding swells due to Teddy. 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 today 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 today and Thursday after it becomes a strong post-tropical cyclone. FORECAST POSITIONS AND MAX WINDS INIT 22/0900Z 38.4N 62.4W 85 KT 100 MPH 12H 22/1800Z 40.9N 63.3W 75 KT 85 MPH 24H 23/0600Z 43.9N 62.9W 65 KT 75 MPH 36H 23/1800Z 47.5N 60.5W 55 KT 65 MPH...POST-TROP/EXTRATROP 48H 24/0600Z 52.0N 57.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 60H 24/1800Z 57.0N 53.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 25/0600Z 61.0N 52.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 96H 26/0600Z...DISSIPATED $$ Forecaster Pasch |