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Hurricane Lee Discussion Number  34
NWS National Hurricane Center Miami FL       AL132023
500 PM AST Wed Sep 13 2023
 
The Air Force Hurricane Hunters investigated Lee earlier this
afternoon and found that the hurricane has lost some strength.  The
initial intensity is lowered to 90 kt based on the aircraft data.
Although the core winds have decreased some, the wind field has
become quite expansive, with the hurricane-force winds now extending
roughly 100 n mi away from the center.  The satellite appearance of
Lee has been relatively steady state through the day and there is
still evidence of concentric eyewalls.
 
Lee's forward speed is beginning to increase, and it is now moving
north-northwestward at 9 kt.  A progressively faster motion to the
north on the west side of a subtropical ridge is forecast during the
next couple of days, taking the core of the system to the west of
Bermuda Thursday and Thursday night.  The combination of a shortwave
trough over the Mid-Atlantic States and a building ridge extending
into Atlantic Canada should cause Lee to turn slightly to the left
Friday night and Saturday, which will likely bring Lee close to
southeastern New England before it moves near or over Maine and 
Atlantic Canada later in the weekend.   The GFS and ECMWF models 
have converged, and are now near the previous NHC track forecast.  
The new NHC track forecast is again just an update of the previous 
one and near the various consensus models.
 
The environment ahead of Lee is expected to gradually become less 
conducive for the hurricane as it moves into a region of higher 
wind shear, drier air, and over progressively cooler SSTs.  These 
conditions favor weakening, but since the system is so large the 
weakening process should be slow.  The NHC intensity forecast is a 
little lower than the previous one, in part due to the initial lower 
wind speed, and remains near the HCCA and IVCN guidance.  
Regardless of the details, there is high confidence that Lee will be 
a large hurricane near the coast of New England Friday night and 
Saturday.
 
It should again be noted that the 34- and 50-kt wind speed
probabilities beyond 36 hours in the text and graphical products are
likely underestimating the risk of those winds occurring.  This is
because the forecast wind field of Lee is considerably larger than
average compared to the wind field used to derive the wind speed
probability product.
 
 
KEY MESSAGES:
 
1. Tropical storm conditions, heavy rainfall, and high surf are
expected to impact Bermuda beginning early Thursday, and a Tropical
Storm Warning is in effect for the island.
 
2. Hurricane conditions, heavy rainfall, and coastal flooding are
possible in portions of eastern Maine on Saturday, and a Hurricane
Watch has been issued for that area.
 
3. There is the potential for life-threatening storm surge flooding
in portions of southeastern Massachusetts, including Cape Cod and
Nantucket, late Friday and Saturday, where a Storm Surge Watch has
been issued.
 
4. Tropical storm conditions are possible over a large portion of
coastal New England, including Cape Cod, Nantucket,  Martha's
Vineyard, and Block Island, where a Tropical Storm Watch has been
issued.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  13/2100Z 27.4N  67.6W   90 KT 105 MPH
 12H  14/0600Z 28.7N  68.1W   90 KT 105 MPH
 24H  14/1800Z 30.9N  68.2W   85 KT 100 MPH
 36H  15/0600Z 33.4N  67.8W   80 KT  90 MPH
 48H  15/1800Z 36.4N  67.2W   75 KT  85 MPH
 60H  16/0600Z 39.7N  66.9W   70 KT  80 MPH
 72H  16/1800Z 42.6N  66.9W   65 KT  75 MPH
 96H  17/1800Z 47.7N  63.8W   45 KT  50 MPH...POST-TROP/EXTRATROP
120H  18/1800Z 52.3N  52.1W   35 KT  40 MPH...POST-TROP/EXTRATROP
 
$$
Forecaster Cangialosi
 
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