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HURRICANE DARBY DISCUSSION NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP052016
800 AM PDT THU JUL 14 2016

Darby still appears to be feeling the effects of 10-15 kt of
northeasterly shear.  Recent microwave images continue to show a
mid-level eye, but the deep convection has an asymmetric structure,
primarily focused to the south and southwest of the center.
Subjective and objective Dvorak estimates have not changed during
the past six hours, and the initial intensity is therefore held at
70 kt.  Although Darby is moving over a relative cool spot in the
ocean, SSTs are still plenty warm to support strengthening for the
next 36 hours.  A limiting factor may be continued vertical shear,
which does not seem to have decreased as the models had been
indicating.  The SHIPS guidance now shows the shear staying up
between 10-15 kt during the next 24 hours, so only a little more
strengthening is shown in the official forecast.  The new NHC
forecast shows a slightly lower peak intensity, and it should be
noted that this forecast is still near the high end of the
guidance.  Much colder SSTs, on the order of 24-25 degrees Celsius,
should contribute to weakening beyond 48 hours.

The initial motion remains westward, or 280/11 kt.  A well-
established ridge to the north of Darby should continue steering
the cyclone westward during the next five days.  With the exception
of the GFDL and HWRF models, which are located along the northern
edge of the guidance envelope, the track models are tightly
clustered and are showing more agreement than yesterday.  The NHC
forecast is south of the TVCE model consensus, and is very close to
the previous official forecast and an average of the GFS and ECMWF
models.

FORECAST POSITIONS AND MAX WINDS

INIT  14/1500Z 15.9N 116.9W   70 KT  80 MPH
 12H  15/0000Z 16.3N 118.7W   75 KT  85 MPH
 24H  15/1200Z 16.7N 121.1W   80 KT  90 MPH
 36H  16/0000Z 17.0N 123.2W   80 KT  90 MPH
 48H  16/1200Z 17.2N 125.2W   80 KT  90 MPH
 72H  17/1200Z 17.4N 128.7W   65 KT  75 MPH
 96H  18/1200Z 17.8N 132.5W   55 KT  65 MPH
120H  19/1200Z 18.5N 137.0W   45 KT  50 MPH

$$
Forecaster Berg

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