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TROPICAL DEPRESSION TWENTY-ONE-E DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP212015
200 AM MST THU NOV 19 2015

Tropical Depression Twenty-One-E remains poorly organized.  While
the convection has increased during the past several hours, the
low-level center appears to be east of the southern end of the
convective area due to ongoing southeasterly shear.  Satellite
intensity estimates are 30 kt from both TAFB and SAB, and thus the
initial intensity is unchanged from the previous advisory.

The initial motion is a rather uncertain 355/5.  A developing mid-
to upper-level ridge to the north and northeast of the depression
should result in a turn toward the west-northwest during the next
24 hours, with this motion continuing through 48 hours.  After that
time, a mid-latitude westerly trough moving into the northeastern
Pacific should break the ridge with the depression turning
northwestward and northward.  While the guidance is in general
agreement with this scenario, after 72 hours there is still a
significant spread as to where the depression may make the
northward turn.  The new forecast track is a little to the south of
the multi-model consensus through 72 hours, then is a little east of
it after that time.

The depression is expected to remain over warm sea surface
temperatures for the next three days or so, and the current shear
is forecast to subside to low values between 12-48 hours.  However,
despite these apparently favorable conditions, the intensity
guidance forecasts only modest strengthening during the next couple
of days.  After that time, increasing southwesterly shear and
decreasing sea surface temperatures should cause the cyclone to
weaken.  The new intensity forecast is the same as the previous
forecast, and it lies near the upper edge of the guidance envelope.


FORECAST POSITIONS AND MAX WINDS

INIT  19/0900Z 13.7N 106.1W   30 KT  35 MPH
 12H  19/1800Z 14.4N 106.7W   35 KT  40 MPH
 24H  20/0600Z 15.2N 108.3W   40 KT  45 MPH
 36H  20/1800Z 16.0N 110.0W   45 KT  50 MPH
 48H  21/0600Z 16.7N 111.4W   45 KT  50 MPH
 72H  22/0600Z 18.0N 113.5W   40 KT  45 MPH
 96H  23/0600Z 19.5N 114.5W   30 KT  35 MPH
120H  24/0600Z 21.5N 114.5W   20 KT  25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Beven

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