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Hurricane Lee Discussion Number  25
NWS National Hurricane Center Miami FL       AL142017
500 AM AST Sun Sep 24 2017

Since the earlier special advisory issued to make Lee a hurricane,
the eye has become much better defined in IR imagery, indicating
that the hurricane has continued to rapidly intensify.  The initial
intensity has therefore been increased to 75 kt, based on an
application of the Dvorak technique to the latest IR imagery. It
should be noted that in this case, the intensity is fairly uncertain
given the lack of ground truth and the small size of the cyclone.

At this point, it is hard to judge how long this period of rapid
intensification will continue.  On one hand, Lee is expected to
remain in a relatively unstable and low-shear environment for the
next several days.  On the other, despite the clearing of the eye,
cloud tops have not cooled significantly overnight, and the slow
motion of Lee allows the possibility that the storm could begin to
interact with its own cold wake.  The NHC forecast brings Lee to
near major hurricane strength in 24 h, and then keeps Lee around
that intensity through day 4, similar to the FSSE model.  By the end
of the forecast, higher shear, due in part to the outflow of
Hurricane Maria, could cause Lee to weaken, so the NHC forecast is a
little lower at that point.

Lee is drifting southward for now, but a southeastward motion is
still forecast to begin later today.  Very little change has been
made to the NHC forecast, which is mainly just an update of the
previous one.  The models have come into better agreement that Lee
will be primarily steered for the next several days by a mid-level
ridge building to the northwest.  By day 5, a trough associated
with Maria and the subtropical ridge should cause Lee to begin
recurving.  Since the model spread has decreased, confidence in
that aspect of the forecast has increased this morning.


FORECAST POSITIONS AND MAX WINDS

INIT  24/0900Z 31.8N  50.1W   75 KT  85 MPH
 12H  24/1800Z 31.6N  49.6W   85 KT 100 MPH
 24H  25/0600Z 31.1N  48.9W   95 KT 110 MPH
 36H  25/1800Z 30.6N  48.8W   95 KT 110 MPH
 48H  26/0600Z 30.2N  49.4W   95 KT 110 MPH
 72H  27/0600Z 30.5N  51.3W   90 KT 105 MPH
 96H  28/0600Z 32.0N  52.5W   90 KT 105 MPH
120H  29/0600Z 34.5N  51.4W   80 KT  90 MPH

$$
Forecaster Zelinsky

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