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Hurricane Teddy Forecast Discussion Number 36
2020-09-21 10:42:46| National Hurricane Center (Atlantic)
Issued at 500 AM AST Mon Sep 21 2020 000 WTNT45 KNHC 210842 TCDAT5 Hurricane Teddy Discussion Number 36 NWS National Hurricane Center Miami FL AL202020 500 AM AST Mon Sep 21 2020 Where Teddy once had a ragged eye has now become a dry slot, an indication that its eyewall is becoming less defined. Some southwesterly shear and the fact that Teddy is beginning to move over the cold wake of former Hurricane Paulette are probably contributing to the degradation of Teddy's structure. Based on this trend, the intensity estimate is lowered slightly to 85 kt. An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate Teddy later this morning and will give a better assessment of the hurricane's winds. For now, little change was made to the NHC track or intensity forecasts. Teddy is beginning to interact with a large deep layer trough and frontal system that will play a big role in its evolution during the next couple of days. For the remainder of today, Teddy should remain fairly distinct from the front, moving east and northeast of Bermuda. As it begins to merge with that system on Tuesday, a slight deflection toward the north-northwest is likely, and it is possible Teddy could quickly become post-tropical if it merges with the front at that time. The most recent ECMWF and GFS runs suggest that Teddy will maintain a warm core a little longer than than that as it moves over the Gulf Stream. Regardless of its exact classification, once Teddy moves north of the Gulf Stream and over much cooler waters, it is forecast to weaken below hurricane strength and become extratropical. Even with a decrease in its highest winds, Teddy will likely be producing a large area of tropical-storm-force winds when it approaches Atlantic Canada in a couple of days. After moving over Atlantic Canada, Teddy is expected to accelerate northeastward and ahead of, and then merge with, another mid-latitude trough approaching from the northwest. Teddy's size will likely increase substantially during the next couple of days as it moves northward and interacts with the aforementioned frontal system. Gale force winds are likely along portions of the near shore waters of the northeast U.S. Please see products from your local office for more information about marine hazards. Extremely dangerous surf conditions with 20-ft waves have been reported on the south shore of Bermuda, and officials are encouraging residents to avoid going into or near the water. Key Messages: 1. The center of Teddy is forecast to move east of Bermuda today. Wind gusts near tropical-storm-force have been reported on the island and tropical storm conditions could continue into Monday evening. 2. 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 there is an increasing risk of direct impacts from wind, rain, and storm surge. A Tropical Storm Watch is in effect for portions of Nova Scotia, and heavy rainfall across Atlantic Canada is expected with Teddy between Tuesday and Thursday after it becomes a strong post-tropical cyclone. 3. 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 could cause life-threatening surf and rip current conditions. FORECAST POSITIONS AND MAX WINDS INIT 21/0900Z 30.3N 63.2W 85 KT 100 MPH 12H 21/1800Z 32.6N 62.6W 85 KT 100 MPH 24H 22/0600Z 36.7N 62.9W 90 KT 105 MPH 36H 22/1800Z 39.7N 63.8W 80 KT 90 MPH 48H 23/0600Z 42.6N 63.4W 70 KT 80 MPH...POST-TROP/EXTRATROP 60H 23/1800Z 46.2N 61.4W 55 KT 65 MPH...POST-TROP/INLAND 72H 24/0600Z 50.0N 57.5W 40 KT 45 MPH...POST-TROP/INLAND 96H 25/0600Z...DISSIPATED $$ Forecaster Zelinsky
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