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Tropical Storm Lee Discussion Number   5
NWS National Hurricane Center Miami FL       AL132023
1100 AM AST Wed Sep 06 2023
 
Recent geostationary and microwave satellite imagery shows that the
convective structure of Lee continues to improve.  Visible imagery
shows a well-defined curved band of convection that wraps around
the eastern portion of the circulation, and a couple of earlier
microwave images revealed a ragged mid-level eye that was open to
the north.  The low-level structure noted in the 1156 UTC GMI
microwave overpass was quite organized with a well-defined
low-level eye feature.  The latest subjective Dvorak T-numbers from
SAB and TAFB were T3.5 (55 kt), but given the continued increase in
structure the initial intensity has been raised to 60 kt.
 
Lee is moving west-northwestward at about 12 kt to the south side
of a low- to mid-level ridge over the central Atlantic.   The ridge
is forecast to remain intact for the next several days and a
west-northwestward motion at around the same forward speed is
expected through the weekend.  The track guidance continues to
show that the core of Lee will pass to the north of the
northern Leeward Islands, however interests in those islands
should continue to monitor the latest forecasts as the typical
three- and four-day NHC track errors are about 90 and 125 n mi,
respectively.  The NHC track forecast is again along the southern
side of the guidance envelope, between the faster and farther south
HFIP corrected consensus model, and the TVCA multi-model consensus
aid.
 
Despite the continued increase in organization there appears to be
some east-northeasterly shear over Lee. The shear is forecast to
relax within the next 24 hours, and given the well-organized
low-level structure of the cyclone, steady to rapid strengthening
appears likely as Lee traverses SSTs of 29-30C during the next few
days.  The NHC intensity forecast is similar to the previous
advisory, bringing Lee to hurricane strength very soon, and to a
major hurricane within 48 hours. Continued strengthen seems likely
after that time, but hard-to-predict eyewall replacement cycles
could cause some fluctuations in intensity later in the weekend and
early next week.  The NHC intensity forecast is near the upper-end
of the guidance and calls for Lee to reach category 4 intensity in
two to three days.
 
 
KEY MESSAGES:
 
1. Lee is forecast to become a major hurricane by early Saturday and
could bring impacts to the northern Leeward Islands this weekend.
While it is too soon to determine the location and magnitude of
these possible impacts, interests in this area should monitor the
progress of Lee and further updates to the forecast.
 
2. Swells generated by Lee are expected to reach portions of the
Lesser Antilles on Friday.  These swells are likely to cause
life-threatening surf and rip current conditions.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  06/1500Z 14.1N  45.5W   60 KT  70 MPH
 12H  07/0000Z 14.8N  47.3W   75 KT  85 MPH
 24H  07/1200Z 15.7N  49.6W   85 KT 100 MPH
 36H  08/0000Z 16.6N  52.2W   95 KT 110 MPH
 48H  08/1200Z 17.6N  54.7W  105 KT 120 MPH
 60H  09/0000Z 18.7N  56.9W  120 KT 140 MPH
 72H  09/1200Z 19.8N  59.2W  130 KT 150 MPH
 96H  10/1200Z 21.5N  62.8W  130 KT 150 MPH
120H  11/1200Z 22.9N  65.7W  130 KT 150 MPH
 
$$
Forecaster Brown
 
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