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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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