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Hurricane TEDDY


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Hurricane Teddy Discussion Number  30
NWS National Hurricane Center Miami FL       AL202020
500 PM AST Sat Sep 19 2020
 
The earlier eyewall replacement cycle occuring in Teddy since last 
night appears to have completed. There is now a more pronounced 
outer ring of convection noted in satellite and microwave imagery, 
and a large ragged eye is beginning to appear in the satellite 
images. The latest satellite intensity estimates from TAFB and 
UW-CIMSS ADT support keeping the initial intensity at 105 kt. A 
U.S. Air Force Reserve Hurricane Hunter aircraft is scheduled to 
investigate the hurricane later this evening. 
 
There is no change to the forecast intensity and structure for 
Teddy. The hurricane will be moving over slightly cooler waters 
caused by upwelling from Paulette over the next 24h and this should 
cause the hurricane to slowly weaken. However, in about 36 h as 
the system passes east of Bermuda, the cyclone's wind field is 
forecast to begin rapidly expanding as it interacts with an 
approaching frontal system. By 48 h, vertical wind shear is expected 
to dramatically increase as Teddy becomes embedded in the flow 
around a sharp mid-latitude upper-level trough. The interaction of 
the cyclone with both the front and trough should cause Teddy to 
begin an extratropical transition, with this transition expected to 
be completed by 72 h. This transition timing is in agreement with 
the global models. Once this transition occurs, the post-tropical 
cyclone is forecast to rapidly weaken, but is still expected to be 
a powerful extratropical cyclone as it approaches Atlantic Canada 
early next week. The latest NHC intensity forecast is little changed 
from the previous one and is near the SHIPS and HFIP corrected 
consensus HCCA. 

Teddy jogged a little west of track today, but the longer term 
motion is still northwestward at about 11 kt. This motion is 
expected to continue through most of the day Sunday. Teddy should 
then turn northward to north-northeastward late Sunday as it 
approaches a frontal system over the western Atlantic. This pattern 
should steer the hurricane east of Bermuda, though the hurricane's 
large wind field means that the island will still likely experience 
tropical storm conditions beginning by Sunday evening and continuing 
into Monday evening. A slight turn to the north then perhaps the 
north- northwest with a faster forward motion should occur Monday 
night into Tuesday as Teddy pivots around the upper trough. By 
Tuesday night, the cyclone is forecast to turn northeastward as the 
upper trough to its southwest begins to lift into the higher 
latitudes.
 
Teddy is producing an extensive area of large waves and swells
which are impacting much of the western Atlantic basin.  See the
Key Messages below.
 
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  19/2100Z 26.7N  60.2W  105 KT 120 MPH
 12H  20/0600Z 27.9N  61.6W  100 KT 115 MPH
 24H  20/1800Z 29.1N  62.7W   95 KT 110 MPH
 36H  21/0600Z 30.7N  62.7W   90 KT 105 MPH
 48H  21/1800Z 33.6N  61.8W   90 KT 105 MPH
 60H  22/0600Z 38.3N  61.9W   85 KT 100 MPH
 72H  22/1800Z 41.9N  62.7W   80 KT  90 MPH...POST-TROP/EXTRATROP
 96H  23/1800Z 47.7N  58.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
120H  24/1800Z 55.5N  45.5W   45 KT  50 MPH...POST-TROP/EXTRATROP
 
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Forecaster Latto
 
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