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HURRICANE DARBY DISCUSSION NUMBER  25
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP052016
200 PM PDT SUN JUL 17 2016

Darby's eye has filled in during the day, and microwave data
indicate that the eyewall has opened up on its southeastern side.
Dvorak estimates are slowly coming down, and the initial intensity
is lowered to 80 kt based on Dvorak Current Intensity numbers which
range from 77-90 kt from SAB, TAFB, and UW-CIMSS ADT.  The center
of Darby is approaching the 24C SST isotherm, and it should reach
waters around 23C in about 12 hours.  After that time, SSTs will
slowly warm up to between 26-27C by the end of the forecast period.
Vertical shear is expected to remain low for another 2-3 days and
then increase to around 20 kt from the west by day 5.  Considering
all these factors, fairly quick weakening is expected during the
next 24 hours while Darby is over the coldest water, followed by
more gradual weakening through day 5.  The NHC intensity forecast
closely follows the ICON intensity consensus for the entire forecast
period, and Darby is likely to weaken to a tropical storm in about
24 hours.

The initial motion is 275/8 kt.  Darby is expected to gain some
latitude through day 3 and then lose latitude on days 4 and 5, but
the ridge to the north should maintain the cyclone on a general
westward heading for the entire forecast period.  The track guidance
remains tightly clustered with no noteworthy shifts in the overall
envelope on this forecast cycle.  The updated NHC forecast is
therefore very similar to the previous one and is close to a
consensus of the GFS and ECMWF models.

FORECAST POSITIONS AND MAX WINDS

INIT  17/2100Z 18.3N 128.3W   80 KT  90 MPH
 12H  18/0600Z 18.5N 129.9W   70 KT  80 MPH
 24H  18/1800Z 18.8N 132.0W   60 KT  70 MPH
 36H  19/0600Z 19.2N 134.4W   55 KT  65 MPH
 48H  19/1800Z 19.6N 136.7W   50 KT  60 MPH
 72H  20/1800Z 19.8N 141.4W   40 KT  45 MPH
 96H  21/1800Z 19.0N 146.0W   35 KT  40 MPH
120H  22/1800Z 18.0N 150.5W   35 KT  40 MPH

$$
Forecaster Berg

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