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HURRICANE DARBY DISCUSSION NUMBER  26
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP052016
800 PM PDT SUN JUL 17 2016

Darby has not weakened since the last advisory; in fact the
hurricane looks a little more impressive than it did earlier today.
Although central convection has not strengthened appreciably, the
CDO has become more symmetric and the eye a little more distinct.
The current intensity estimate is held at 80 kt which is close to a
consensus of Dvorak estimates from SAB and TAFB, along with ADT
estimates from UW-CIMSS.  Darby is over SSTs near 24 deg C and will
be moving over slightly cooler waters overnight.  After that, the
cyclone should traverse SSTs near 25 deg C through 48 hours.
Gradual weakening is predicted due to these somewhat cool waters,
and Darby should lose hurricane status in about 24 hours with
additional weakening thereafter.  In 72 hours or so, the ocean under
Darby will warm slightly to 25-26 deg C but by that time the
vertical shear, which had been low, is forecast to increase and this
should prevent restrenghtening in the latter part of the forecast
period.  The official intensity forecast is close to the latest
model consensus.

Darby continues on a westward track and the initial motion estimate
remains 275/8 kt.  There is no reason to change the track forecast
from the previous advisory package.  A narrow east-west oriented
mid-level ridge is expected to be maintained to the north of Darby
for the next several days.  Late in the period, a mid-level high
builds to the northwest of the tropical cyclone which should cause
a slightly south of west motion.  The official forecast lies a
little south of the dynamical model consensus and is a blend of the
latest GFS and ECMWF predictions.

FORECAST POSITIONS AND MAX WINDS

INIT  18/0300Z 18.4N 129.0W   80 KT  90 MPH
 12H  18/1200Z 18.6N 130.7W   70 KT  80 MPH
 24H  19/0000Z 19.0N 133.0W   60 KT  70 MPH
 36H  19/1200Z 19.4N 135.4W   55 KT  65 MPH
 48H  20/0000Z 19.7N 137.7W   50 KT  60 MPH
 72H  21/0000Z 19.5N 142.3W   45 KT  50 MPH
 96H  22/0000Z 18.7N 147.0W   35 KT  40 MPH
120H  23/0000Z 18.0N 151.0W   35 KT  40 MPH

$$
Forecaster Pasch

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