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Tropical Depression TWENTY-ONE-E


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TROPICAL DEPRESSION TWENTY-ONE-E DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP212014
200 AM PDT THU OCT 30 2014

Deep convection associated with the low pressure area south of
Acapulco, Mexico, has become more concentrated overnight, and recent
microwave and conventional satellite imagery suggest that the
low-level center has become better defined.  Therefore, the system
is being designated as a tropical depression.  The satellite data
indicate that the center is located near the southern edge of the
main convective mass.  Subjective Dvorak T-numbers from TAFB and
SAB are 2.5 and 1.5, respectively.  A blend of these estimates
support an initial wind speed of 30 kt.

The depression is over warm water and expected to remain in a low
shear environment during the next several days.  The main limiting
factor will be some drier air in the low to mid-levels.  As a
result, gradual strengthening is predicted during much of the
forecast period.  The NHC forecast is a little above the intensity
guidance through the first couple of days.  After 72 hours, the
NHC forecast is in good agreement with the HWRF which brings the
cyclone to hurricane strength in about 4 days.  Increasing
south-southwesterly shear could halt any additional strengthening
after that time.

The depression is moving west-northwestward at about 5 kt.  The
depression is forecast to turn west-southwestward later today as a
mid-level ridge builds to the north and northwest of the cyclone.
The ridge is forecast to shift eastward during the next few days,
which should cause the cyclone to turn west-northwestward, then
northwestward in 48 to 72 hours.  After that time, the tropical
cyclone is forecast to turn northward while a mid-latitude trough
approaches the Baja California peninsula.  The track guidance is in
good agreement on this scenario and the NHC track is near the middle
of the guidance envelope.


FORECAST POSITIONS AND MAX WINDS

INIT  30/0900Z 11.0N 100.2W   30 KT  35 MPH
 12H  30/1800Z 11.1N 100.8W   35 KT  40 MPH
 24H  31/0600Z 10.8N 101.8W   40 KT  45 MPH
 36H  31/1800Z 10.3N 102.9W   45 KT  50 MPH
 48H  01/0600Z 10.1N 104.2W   50 KT  60 MPH
 72H  02/0600Z 10.9N 107.7W   60 KT  70 MPH
 96H  03/0600Z 14.0N 110.0W   70 KT  80 MPH
120H  04/0600Z 18.0N 109.0W   70 KT  80 MPH

$$
Forecaster Brown

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