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TROPICAL DEPRESSION NINETEEN-E DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP192015
800 PM PDT THU OCT 15 2015

The cloud pattern of the depression has appeared ragged in satellite
images most of the day, and the latest Dvorak CI-numbers from TAFB
and SAB have decreased to 1.5/25 kt.  The associated deep convection
does not have much curvature and it is largely confined to areas to
the north and west of the estimated center.  Based on the degraded
appearance, the initial wind speed is lowered slightly to 25 kt.

It is not clear why the depression has not strengthened today as the
large-scale environmental conditions have been quite conducive for
intensification.  The depression is expected to remain in a low wind
shear and high moisture environment and over warm water for at least
the next few days.  Therefore, it is assumed that the system will
have the opportunity to gain strength.  The GFS, as well as the
GFS-based SHIPS and LGEM guidance, are the most aggressive models
and show the cyclone becoming a hurricane in a couple of days with
continued strengthening thereafter.  Conversely, the GFDL and HWRF
models show much less strengthening.  Given the poor initial
structure of the cyclone, the official intensity forecast has been
lowered in the short term but remains relatively unchanged from the
previous prediction at the later forecast times.

The depression is moving westward at about 11 kt steered by a
subtropical ridge to its north.  A continued westward motion but at
a slower pace is forecast during the next couple of days while the
ridge weakens in place.  After that time, a turn to the northwest
is expected as a weakness develops in the ridge east of the
Hawaiian Islands.  Although there is considerable spread in the
guidance on when the northwestward turn should occur, the models
agree on the overall theme. The new official track forecast is
essentially an update of the previous one for the first couple of
days, but then is shifted westward to come into better agreement
with the latest model consensus aids.

FORECAST POSITIONS AND MAX WINDS

INIT  16/0300Z 10.2N 122.1W   25 KT  30 MPH
 12H  16/1200Z 10.1N 124.0W   30 KT  35 MPH
 24H  17/0000Z 10.0N 126.2W   35 KT  40 MPH
 36H  17/1200Z  9.9N 128.0W   45 KT  50 MPH
 48H  18/0000Z 10.2N 129.6W   55 KT  65 MPH
 72H  19/0000Z 11.1N 132.3W   75 KT  85 MPH
 96H  20/0000Z 12.7N 135.1W   85 KT 100 MPH
120H  21/0000Z 15.1N 137.8W   85 KT 100 MPH

$$
Forecaster Cangialosi

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