[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 200244
TCDAT3

TROPICAL DEPRESSION THIRTEEN DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132016
1100 PM AST MON SEP 19 2016

The coverage of deep convection associated with the depression has
decreased somewhat during the past several hours, but the
circulation remains well established with several fragmented
curved bands. Satellite intensity estimates from TAFB and SAB
support maintaining the initial wind speed of 30 kt.

The cyclone is moving west-northwestward at 8 kt.  A weakness in
the subtropical ridge over the east-central Atlantic is expected to
persist for the next several days due to a series of shortwave
troughs moving through the area.  As a result, a continued
west-northwestward to northwestward motion at about the same forward
speed is expected throughout the forecast period. The models are in
fair agreement, and the NHC track prediction lies on the left side
of the guidance envelope, in best agreement with the ECMWF model.

The environmental conditions for strengthening during the next
several days are mixed.  Although the shear is expected to be light
and waters warm during the next couple of days, the atmosphere is
not overly moist in the vicinity of the depression.  These
conditions should allow for slow strengthening during the next 48
hours.  Beyond that time, however, the system is expected to move
in less favorable conditions of stronger shear, even drier air, and
more marginal SSTs.  These conditions should halt strengthening
and induce gradual weakening.  The NHC intensity forecast lies
close to the intensity model consensus for the first few days, but
is lower than the consensus at days 4 and 5 given the expected
hostile conditions.

FORECAST POSITIONS AND MAX WINDS

INIT  20/0300Z 14.2N  29.0W   30 KT  35 MPH
 12H  20/1200Z 15.0N  30.4W   35 KT  40 MPH
 24H  21/0000Z 16.1N  32.2W   40 KT  45 MPH
 36H  21/1200Z 17.2N  34.0W   45 KT  50 MPH
 48H  22/0000Z 18.1N  35.7W   50 KT  60 MPH
 72H  23/0000Z 20.0N  38.9W   45 KT  50 MPH
 96H  24/0000Z 22.0N  42.0W   35 KT  40 MPH
120H  25/0000Z 25.0N  44.5W   30 KT  35 MPH

$$
Forecaster Cangialosi/Brown
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