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Hurricane Teddy Forecast Discussion Number 42
2020-09-22 22:55:07| National Hurricane Center (Atlantic)
Issued at 500 PM AST Tue Sep 22 2020 000 WTNT45 KNHC 222054 TCDAT5 Hurricane Teddy Discussion Number 42 NWS National Hurricane Center Miami FL AL202020 500 PM AST Tue Sep 22 2020 Teddy is a very impressive cyclone on satellite images this afternoon, even from full-disk images. The hurricane's circulation is over 1000 miles wide, with an enormous distinct comma shape and frontal features especially in the eastern semicircle. As far as what to call the system convection has actually deepened near the center during the past several hours, and an AMSR pass around 1700 UTC showed that the system still had a low-level eye feature. For that reason and for simplicity's sake, the system will remain a hurricane on this advisory, although it is obviously a hybrid low with many characteristics of a non-tropical cyclone. The initial wind speed is lowered to 80 kt, assuming the filling trend reported by the last NOAA Hurricane Hunter mission continued. The wind radii are expanded based on ASCAT data, with tropical-storm-force winds over eastern Nova Scotia already. The hurricane is forecast to transition into a post-tropical cyclone later tonight or early tomorrow due to the cooler waters north of the Gulf Stream likely weakening any central convection. Teddy should decay below hurricane-strength before reaching Nova Scotia and steadily weaken as it moves over the even colder waters in the Gulf of St. Lawrence. The new intensity forecast is a little lower than the previous one and is closest to the GFS model. Teddy is moving northward now and should turn north-northeastward tomorrow ahead of the next trough in the mid-latitudes. This will take Post-Tropical Teddy over Nova Scotia and near Newfoundland during the next couple of days, with the cyclone likely being absorbed into a larger extratropical cyclone west of Greenland in 2-3 days. There are no significant changes to report, though there has been a slight westward shift of the track near Newfoundland. The hazards from Teddy are extending at quite a distance from the center of this hurricane. In addition to the 500-mile wind radii in the northeastern quadrant, Canadian buoy 44150 has recently reported 42 ft (13 m) significant wave heights, with the buoy still about 90 n mi from the center. 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. The most significant hazard expected from Teddy is large destructive waves forecast along the southern coast of Nova Scotia through Wednesday. 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. Tropical Storm Watches and Warnings are in effect for portions of Nova Scotia, Newfoundland, Prince Edward Island and the Magdalen Islands, and heavy rainfall across Atlantic Canada is expected through Thursday. FORECAST POSITIONS AND MAX WINDS INIT 22/2100Z 41.1N 64.2W 80 KT 90 MPH 12H 23/0600Z 43.1N 63.5W 65 KT 75 MPH...POST-TROPICAL 24H 23/1800Z 47.0N 60.7W 55 KT 65 MPH...POST-TROP/EXTRATROP 36H 24/0600Z 51.5N 56.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 48H 24/1800Z 56.5N 53.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 60H 25/0600Z...DISSIPATED $$ Forecaster Blake
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