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TROPICAL STORM DARBY DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP052016
900 PM MDT TUE JUL 12 2016

This evening's satellite presentation shows a considerable amount
of improvement in Darby's cloud pattern.  It appears as though
the northeasterly shear, which was curtailing development, is
decreasing.  Deep convection has developed over the circulation
center with -75C cloud tops, and a strong curved banding feature is
evident in the western portion of the cyclone.  Dvorak satellite
intensity estimates are T3.5 from both agencies, and the initial
intensity is increased to 55 kt for this advisory.  Further
strengthening is expected, and the majority of the intensity
guidance indicates that Darby will become a hurricane in 12 hours.
Models, particularly the LGEM, Decay SHIPS, and the FSU ensemble,
are showing a stronger hurricane in 48-60 hours compared to earlier
runs, and the forecast follows suit. Gradual weakening is forecast
beyond day 3 as Darby traverses decreasing sea surface temperatures.

Darby is moving a little to the left of the previous advisory, now
260/9 kt.  The cyclone should continue on a general westward track
during the next 48 hours south of a well established mid- to upper
level ridge extending from Mexico.  The GFDL and the GFS are still
indicating a stronger break in the ridge beyond day 3 as a
mid-latitude trough approaches the west coast of the United States.
The other global models indicate the ridge maintaining strength
through day 5.  The official forecast basically splits the two
solutions and sides with the multi-model consensus and the FSU
superensemble.

FORECAST POSITIONS AND MAX WINDS

INIT  13/0300Z 15.4N 110.4W   55 KT  65 MPH
 12H  13/1200Z 15.3N 111.8W   65 KT  75 MPH
 24H  14/0000Z 15.3N 114.1W   75 KT  85 MPH
 36H  14/1200Z 15.4N 116.4W   80 KT  90 MPH
 48H  15/0000Z 15.5N 118.9W   85 KT 100 MPH
 72H  16/0000Z 16.2N 123.3W   85 KT 100 MPH
 96H  17/0000Z 16.8N 127.2W   75 KT  85 MPH
120H  18/0000Z 17.7N 131.1W   65 KT  75 MPH

$$
Forecaster Roberts

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