[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 112044
TCDAT3

Hurricane Lee Discussion Number  26
NWS National Hurricane Center Miami FL       AL132023
500 PM AST Mon Sep 11 2023

Lee continues to exhibit a double eyewall structure as reported by
the Air Force Hurricane Hunters and seen in recent microwave images.
The inner eyewall is open on the south side, but the outer eyewall
is completely closed and has contracted slightly from the earlier
NOAA P-3 aircraft mission.  The minimum pressure is the same as
before, 948 mb, but the initial wind speed is nudged downward to 100
kt based on the aircraft data.

The major hurricane has jogged a little to the left recently, and
the initial motion is estimated to be 290/7 kt.  The models are
similar to the previous runs, and no big changes were made to the
NHC track forecast. A continued slow motion between west-northwest
and northwest is expected during the next couple of days as Lee
remains steered by a mid-level high to its north-northeast. Beyond a
couple of days, the ridge is expected to shift eastward as a mid- to
upper-level trough amplifies over the eastern U.S.  This pattern
change should cause Lee to turn northward with an increase in
forward speed.  Lee is likely to pass near, but to the west of
Bermuda, late Thursday and Friday and then be situated offshore of
the mid-Atlantic states and New England late Friday and Saturday.

Given the current concentric eyewall structure, it seems likely that
Lee will fluctuate in strength in the short term.  However, since
the hurricane will remain in generally conducive conditions during
the next couple of days, it could restrengthen if the eyewall cycle
completes.  Lee is likely to move over a cool SST wake left behind
by Hurricanes Idalia and Franklin later this week, and cross over
the north wall of the Gulf Stream by the end of the forecast period.
The combination of cooler SSTs, an increase in shear, and dry air
entrainment should cause a steady decay in strength late this week
and over the weekend.  The NHC intensity forecast is an update of
the previous one and near the middle of the guidance envelope.

Although Lee is expected to weaken later in the week, it is expected
to significantly increase in size and hazards will extend well away
from the storm center by the end of the forecast period.


KEY MESSAGES:

1. Dangerous surf and life-threatening rip currents will affect
portions of the northern Leeward Islands, the Virgin Islands, Puerto
Rico, Hispaniola, the Turks and Caicos Islands, the Bahamas,
Bermuda, and most of the U.S East Coast through much of the week.

2. Lee could bring strong winds, rainfall, and high surf impacts to
Bermuda later this week. Interests there should continue to monitor
updates to the forecast of Lee during the next several days.

3. It remains too soon to know what level of additional impacts Lee
might have along the Northeast U.S. coast and Atlantic Canada late
this week and this weekend.  However, wind and rainfall hazards will
likely extend well away from the center as Lee grows in size. Users
should continue to monitor updates to the forecast of Lee during the
next several days.


FORECAST POSITIONS AND MAX WINDS

INIT  11/2100Z 23.6N  64.2W  100 KT 115 MPH
 12H  12/0600Z 24.0N  65.1W  105 KT 120 MPH
 24H  12/1800Z 24.6N  66.1W  105 KT 120 MPH
 36H  13/0600Z 25.3N  66.9W  100 KT 115 MPH
 48H  13/1800Z 26.5N  67.5W  100 KT 115 MPH
 60H  14/0600Z 28.3N  67.8W   95 KT 110 MPH
 72H  14/1800Z 30.3N  67.9W   90 KT 105 MPH
 96H  15/1800Z 35.4N  67.1W   80 KT  90 MPH
120H  16/1800Z 40.8N  67.0W   65 KT  75 MPH

$$
Forecaster Cangialosi
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