Official Discussion issued by the National Hurricane Center

Lee (AL132023) DATA RELEASED: 9/14/2023 9:00:00 PM UTC

Copy of official data

Hurricane Lee Discussion Number  38
NWS National Hurricane Center Miami FL       AL132023
500 PM AST Thu Sep 14 2023

There has been little overall change to the satellite presentation
of Lee since the previous advisory.  Deep convection continues to
develop near the center, but it is primarily confined to the
northern portion of the circulation.  Southwesterly shear and dry
air entrainment is disrupting the convective banding over the
southern portion of the storm.  The initial intensity was lowered
to 75 kt on the 1800 UTC intermediate advisory, and was based
on data from the Air Force Reserve reconnaissance aircraft that was
in the storm through midday.  The initial wind speed remains at
that value for this advisory.  The next reconnaissance mission is
scheduled to investigate Lee this evening. The early aircraft data
along with a couple of fortuitous ASCAT overpasses showed that the
wind field of Lee has continued to expand.  The 50-kt wind radii
extend outward up to 170 n mi over the eastern semicircle of the
storm.  NOAA buoy 41048 located about 75 miles (120 km) west of the 
center of Lee has recently reported a peak one-minute sustained wind 
of 58 kt and a gust to 76 kt and wave heights of around 30 ft.  
Bermuda, located more than 220 miles east-northeast of the center 
has also reported sustained tropical-storm force winds today.   

Lee is moving northward at about 13 kt, which is slightly faster
than before.  Lee should continue to pick up some forward speed as
it moves northward around the western side of a mid-level ridge
over the central Atlantic during the next 12-24 hours.  After that
time a slight bend to the north-northwest is likely late Friday or
early Saturday, and this motion should bring the center of Lee near
or over southwestern Nova Scotia late Saturday.  After that time,
Lee is forecast to turn northeastward over Atlantic Canada.  The
track guidance is still in good agreement, and no significant
changes to the previous official forecast were required.

Increasing southwesterly vertical wind shear and dry air entrainment 
could cause some additional weakening, but baroclinic forcing 
during the early stages of Lee's extratropical transition may help 
to maintain the cyclone's intensity through Friday.  By Friday 
night Lee will be moving over significantly cooler sea surface 
temperatures, and gradual weakening is expected after that time.  
Lee is forecast to complete its transition into an extratropical 
cyclone when it nears Atlantic Canada.  Regardless of Lee's 
designation when it approaches New England and Atlantic Canada, it 
will remain a very large and dangerous cyclone through landfall.


1. Tropical storm conditions, heavy rainfall, and high surf will
continue to impact Bermuda through Friday morning, and a Tropical
Storm Warning is in effect for the island.

2. Hurricane conditions and coastal flooding are possible in
portions of eastern Maine, southern New Brunswick, and western Nova
Scotia on Saturday, and a Hurricane Watch is in effect for that
area.  Tropical storm conditions and coastal flooding are expected 
to begin in southern New England on Friday afternoon, and spread 
northward along the coast of New England through Saturday where 
Tropical Storm warnings are in effect. 

3. Heavy rainfall from Lee may produce localized urban and small
stream flooding across eastern New England and into portions of New
Brunswick and Nova Scotia from Friday night into Saturday night.


INIT  14/2100Z 31.7N  68.3W   75 KT  85 MPH
12H  15/0600Z 33.8N  67.9W   75 KT  85 MPH
24H  15/1800Z 37.0N  66.9W   75 KT  85 MPH
36H  16/0600Z 40.3N  66.6W   70 KT  80 MPH
48H  16/1800Z 43.3N  66.4W   60 KT  70 MPH...POST-TROP/EXTRATROP
60H  17/0600Z 46.0N  65.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
72H  17/1800Z 48.6N  61.4W   40 KT  45 MPH...POST-TROP/EXTRATROP
96H  18/1800Z 53.7N  48.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  19/1800Z...DISSIPATED

Forecaster Brown