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Hurricane Lee Discussion Number 28
NWS National Hurricane Center Miami FL AL142017
1100 PM AST Sun Sep 24 2017
Lee has been relatively steady state in intensity during the last
several hours. The 10 n mi eye of the hurricane remains distinct,
and although the convective pattern around the eye is fairly
symmetric, the cloud tops are not very cold. The latest Dvorak
intensity estimates are 4.5/77 kt from both TAFB and SAB, and ADT
values from CIMSS at the University of Wisconsin are slightly higher
at 4.7/82 kt. Based on these data, the initial wind speed is held
at 80 kt. Recent ASCAT data confirms that Lee is a very compact
hurricane, with tropical-storm-force winds extending only 30 n mi
from the center.
Although wind shear is expected to remain low near Lee during the
next couple of days, the hurricane is likely to be over its own cool
SST wake for part of that time. These marginal SSTs and dry air
will likely cause the system to change little in strength during
the next couple of days. Thereafter, much drier air, a sharp
increase in shear, and a track toward colder water should cause
weakening by the end of the forecast period. The NHC intensity
forecast is identical to the previous one and in best agreement with
the consensus models IVCN and HCCA.
Lee has been drifting east-southeastward during the past 12 hours in
the flow on the south side of a mid- to upper-level trough. The
trough is expected to bypass Lee on Monday, allowing high pressure
to build to the north of the cyclone. This change in the steering
pattern should cause the hurricane to turn westward by Monday night
and Tuesday. By mid-week, another trough is expected to approach
the hurricane, and this one should cause the system to accelerate to
the northeast over the central Atlantic. The NHC track forecast has
been adjusted to the west of the previous one to come into better
agreement with the latest guidance.
FORECAST POSITIONS AND MAX WINDS
INIT 25/0300Z 31.1N 49.5W 80 KT 90 MPH
12H 25/1200Z 31.0N 49.4W 85 KT 100 MPH
24H 26/0000Z 30.7N 49.9W 85 KT 100 MPH
36H 26/1200Z 30.6N 51.2W 85 KT 100 MPH
48H 27/0000Z 30.8N 52.5W 80 KT 90 MPH
72H 28/0000Z 31.8N 54.1W 75 KT 85 MPH
96H 29/0000Z 34.7N 53.0W 70 KT 80 MPH
120H 30/0000Z 40.0N 46.5W 55 KT 65 MPH
$$
Forecaster Cangialosi
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