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HURRICANE DARBY DISCUSSION NUMBER  19
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP052016
200 AM PDT SAT JUL 16 2016

Darby appears to be maintaining its strength.  Satellite images
indicate that the eye of the hurricane has become a bit more
distinct and circular than it was several hours ago.  Although the
cloud tops have warmed a bit in the eyewall, the convective pattern
is quite symmetric.  A blend of the latest Dvorak classifications
from TAFB and SAB, and automated values from CIMSS at the University
of Wisconsin support holding the initial intensity at 90 kt.

Although the wind shear is expected to remain light during the next
several days, the oceanic conditions will soon become unfavorable
for strengthening.  Sea surface temperatures beneath the hurricane
are expected to fall below 26 deg C in about 12 hours, and Darby is
headed for even cooler waters after that.  The cool waters combined
with a progressively drier air mass should induce a gradual
weakening trend beginning later today and continuing during the
next several days.  The NHC intensity forecast is largely an update
of the previous one and is not too different from the intensity
model consensus.

Darby has been wobbling around during the past 12-18 hours, but
smoothing through these positions yields an initial motion estimate
of 295/9 kt.  A gradual turn toward the west is expected during
the next several days as a mid-level ridge builds to the north of
the tropical cyclone.  The model guidance is in fair agreement in
the future track of Darby, and the NHC forecast lies close to the
various consensus aids.

An ASCAT pass from a few hours ago was helpful in estimating the
size of the wind field of Darby.

FORECAST POSITIONS AND MAX WINDS

INIT  16/0900Z 17.6N 123.1W   90 KT 105 MPH
 12H  16/1800Z 18.0N 124.4W   85 KT 100 MPH
 24H  17/0600Z 18.4N 126.0W   75 KT  85 MPH
 36H  17/1800Z 18.8N 127.8W   70 KT  80 MPH
 48H  18/0600Z 19.1N 129.8W   65 KT  75 MPH
 72H  19/0600Z 19.8N 134.2W   50 KT  60 MPH
 96H  20/0600Z 20.1N 138.9W   45 KT  50 MPH
120H  21/0600Z 19.5N 144.0W   40 KT  45 MPH

$$
Forecaster Cangialosi

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