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HURRICANE DARBY DISCUSSION NUMBER  10
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP052016
900 PM MDT WED JUL 13 2016

Darby has developed a large CDO pattern and a 2314Z SSMI/S microwave
pass indicated a 15-20 nmi diameter eye embedded in the center of
the central dense overcast. Subjective intensity estimates are a
consensus T4.0/65 kt from TAFB and SAB, and the latest UW-CIMSS ADT
and AMSU estimates were T4.4/75 kt and 72 kt, respectively. The
advisory intensity of 70 kt is based on an average of these values.

The initial motion estimate is 280/10 kt. The expansive deep-layer
ridge to the north of Darby is forecast by the global models to
remain entrenched across the eastern and central Pacific for the
next several days, which should act to keep Darby moving in a
general westerly direction throughout the 5-day forecast period.
Other than some differences in forward speed, there remains very
little cross-track difference noted among the more reliable models.
The new official track forecast is essentially just an extension of
the previous advisory track, and lies close to a consensus of the
GFS and ECMWF model solutions.

Darby is expected to encounter the most favorable combination of
atmospheric and oceanic conditions during the next 24 hours or so,
and steady intensification is forecast as a result during that time.
By 36-48 h, Darby will be moving across cooler SSTs near 26 deg C
and into a drier airmass, so leveling off of the intensity is
expected. Steady weakening is forecast to begin after that time as
the hurricane moves over 25-26 deg C SSTs. However, the weakening
rate is expected to be a little slower than normal due to low
vertical wind shear conditions that both the GFS and ECMWF models
are forecasting to affect Darby between 72-120 h. The new NHC
intensity forecast is similar to the previous forecast, and closely
follows the SHIPS intensity forecast guidance.

FORECAST POSITIONS AND MAX WINDS

INIT  14/0300Z 15.6N 114.6W   70 KT  80 MPH
 12H  14/1200Z 15.9N 116.5W   80 KT  90 MPH
 24H  15/0000Z 16.3N 119.0W   90 KT 105 MPH
 36H  15/1200Z 16.7N 121.5W   90 KT 105 MPH
 48H  16/0000Z 17.0N 123.6W   85 KT 100 MPH
 72H  17/0000Z 17.5N 127.6W   70 KT  80 MPH
 96H  18/0000Z 18.1N 131.6W   60 KT  70 MPH
120H  19/0000Z 18.9N 136.4W   50 KT  60 MPH

$$
Forecaster Stewart

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