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TROPICAL DEPRESSION THIRTEEN-E DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP132015
300 PM MDT WED AUG 26 2015

The area of low pressure located well to the southwest of the coast
of Mexico has become sufficiently well organized to be classified
as a tropical depression.  Dvorak classifications were T2.0/30 kt
from TAFB and T1.5/25 kt from SAB at 1800 UTC, and the initial
intensity is therefore set at 25 kt.  The environment ahead of the
depression is characterized by low shear, very warm waters, and a
moist atmosphere, so strengthening appears likely throughout the
forecast period.  In fact, some of the intensity models are quite
aggressive.  Both the SHIPS and LGEM models strengthen the cyclone
to category 3 or 4 intensity in five days, and the GFS deepens the
system to a central pressure that typically equates to a category 3
hurricane.  Therefore, the official forecast shows steady
intensification, with the cyclone reaching major hurricane strength
by day 5.  This forecast is slightly below the IVCN intensity
consensus.

The center has been somewhat difficult to locate, but the overall
system has been moving quickly westward with a motion estimate of
280/17 kt.  The depression is located to the south of a strong
mid-level ridge located over northern Mexico and the adjacent
Pacific waters.  This ridge should continue steering the cyclone
westward--with a gradual decrease in forward speed--through day 4.
A breakdown of the ridge by day 5 could then support a
west-northwestward motion at the end of the forecast period.  The
track guidance is in good agreement on this scenario, and the
official forecast is relatively close the model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  26/2100Z 10.8N 113.3W   25 KT  30 MPH
 12H  27/0600Z 11.5N 115.5W   30 KT  35 MPH
 24H  27/1800Z 12.0N 118.1W   35 KT  40 MPH
 36H  28/0600Z 12.3N 120.3W   45 KT  50 MPH
 48H  28/1800Z 12.4N 122.5W   55 KT  65 MPH
 72H  29/1800Z 12.4N 126.5W   75 KT  85 MPH
 96H  30/1800Z 13.0N 130.5W   95 KT 110 MPH
120H  31/1800Z 14.5N 134.0W  100 KT 115 MPH

$$
Forecaster Berg

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