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Tropical Depression Twenty-One-E Discussion Number   1...Corrected
NWS National Hurricane Center Miami FL       EP212019
300 AM CST Sat Nov 16 2019

Corrected time zone in header.

Deep convection associated with the small low pressure area located
well south of the coast of Mexico has continued to increase and
become better organized overnight.  ASCAT data from 03-04Z indicated
that the circulation was well-defined and there were believable
30 kt wind vectors.  The ASCAT revealed a few higher wind vectors,
but they may have been rain contaminated.  Based on these data and
a Dvorak T-number of 2.0 from TAFB, advisories are being initiated
on a 30-kt tropical depression.  The intensity forecast for this
system is a bit tricky as small systems such as this can spin up or
down quite quickly.  In the short-term, a dry and more stable air
from a Gulf of Tehuantepec gap wind event could be entrained into
the northern portion of the circulation today, which could cause a
disruption in the deep convection and/or an elongation of the
circulation.  However, if the small cyclone remains south of the
main area of Tehuantepec winds, low vertical wind shear conditions
favor some intensification.  The NHC intensity forecast leans on the
latter scenario and call for some strengthening during the next 24
hours or so.  After that time, increasing southerly shear is
expected to cause weakening, and the system is forecast to
degenerate into a remnant low in 3 to 4 days.  The intensity is
more uncertain than normal, but is fairly close to the intensity
consensus aids.

The depression is moving westward or 270/10 kt.  The track
forecast is a bit more straightforward as the cyclone should be
steered generally westward to the south of a mid-level ridge located
over southern Mexico during the next couple of days. After that
time, the cyclone is forecast to near the southwestern portion of
the ridge and a west-northwestward heading is predicted.  The
global models are in fairly good agreement on this scenario and the
NHC track follows a blend of the various global model predictions.


FORECAST POSITIONS AND MAX WINDS

INIT  16/0900Z  9.2N  99.2W   30 KT  35 MPH
 12H  16/1800Z  9.0N 100.8W   35 KT  40 MPH
 24H  17/0600Z  8.9N 102.1W   40 KT  45 MPH
 36H  17/1800Z  9.0N 103.1W   40 KT  45 MPH
 48H  18/0600Z  9.4N 104.0W   35 KT  40 MPH
 72H  19/0600Z 10.1N 106.9W   30 KT  35 MPH
 96H  20/0600Z 10.5N 109.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  21/0600Z...DISSIPATED

$$
Forecaster Brown

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