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Hurricane Teddy Forecast Discussion Number 31
2020-09-20 04:54:45| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Sat Sep 19 2020 000 WTNT45 KNHC 200254 TCDAT5 Hurricane Teddy Discussion Number 31 NWS National Hurricane Center Miami FL AL202020 1100 PM AST Sat Sep 19 2020 Some convective cells have been developing within Teddy's large outer eye, and it is possible that this convection is forming an inner eyewall. In any event, observations from an Air Force Hurricane Hunter aircraft indicate that the maximum winds have decreased slightly, to near 100 kt. The hurricane is expected to remain in a low shear environment until tomorrow evening, and to more or less maintain its intensity for 12-24 hours. Thereafter, increasing shear associated with an upper-level trough to the west should cause weakening. Although the shear is predicted by the global models to become fairly strong after 48 hours, the system has a a very large and intense circulation so only slow weakening is expected. By 72 hours, Teddy should merge with a frontal zone to the east of New England and become a strong extratropical cyclone. The official intensity forecast is close to the model consensus. The system's wind field will likely become even larger as the wind field of Teddy interacts within a high pressure system behind a cold front during the next few days. This could prolong the period of strong winds over Bermuda into Monday night. Teddy continues on a general northwestward track or about 315/11 kt. The hurricane should move on the western side of a subtropical high pressure area for the next day or so, and then begin to accelerate northward ahead of a strong mid-tropospheric trough that develops into a cutoff low off the northeast U.S. coast in a couple of days. The interaction of Teddy with this low will likely result in a slight leftward bend of the track around days 2-3. In 4-5 days, post-tropical Teddy is likely to turn north-northeastward to northeastward in the flow on the east side of a broad 500 mb trough. The official track forecast is a blend of the simple and corrected dynamical model consensus predictions. The extent of 12-foot or higher seas associated with Teddy continues to increase. See the Key Message below regarding swells caused by the hurricane. Key Messages: 1. While the center of Teddy is forecast to move east of Bermuda late Sunday or Monday, tropical storm conditions are likely on the island beginning Sunday evening. 2. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada early next week, where there is an increasing risk of direct impacts from wind, rain, and storm surge. Residents there should closely monitor the progress of Teddy and updates to the forecast. 3. Large swells produced by Teddy are expected to affect portions of the Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, the east coast of the United States, and Atlantic Canada during the next few days. These swells could cause life-threatening surf and rip current conditions. FORECAST POSITIONS AND MAX WINDS INIT 20/0300Z 27.3N 61.2W 100 KT 115 MPH 12H 20/1200Z 28.3N 62.3W 100 KT 115 MPH 24H 21/0000Z 29.6N 63.0W 95 KT 110 MPH 36H 21/1200Z 31.6N 62.4W 90 KT 105 MPH 48H 22/0000Z 35.7N 61.8W 90 KT 105 MPH 60H 22/1200Z 39.7N 62.5W 80 KT 90 MPH 72H 23/0000Z 42.5N 62.8W 70 KT 80 MPH...POST-TROP/EXTRATROP 96H 24/0000Z 49.5N 56.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 25/0000Z 57.0N 42.5W 40 KT 45 MPH...POST-TROP/EXTRATROP $$ Forecaster Pasch
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