Tropical Storm VANCE

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TROPICAL STORM VANCE DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP212014
800 PM PDT THU OCT 30 2014

Vance has strengthened a little this evening.  Infrared satellite
images indicate that deep convection has increased slightly to the
northeast of the center and in a band on the south and east sides of
the circulation.  A blend of the latest Dvorak intensity estimates
from TAFB, SAB, and the University of Wisconsin-CIMSS supports
raising the initial wind speed to 40 kt.  Southerly to southwesterly
shear and dry air in the low- to mid-levels of the atmosphere are
currently affecting Vance, and these conditions are expected to
persist for about another day.  Therefore, only slow strengthening
is predicted during that time.  Over the weekend, however, the
atmosphere is expected to moisten near the storm while the shear
lessens, providing a better opportunity for more significant
strengthening.  By the end of the forecast period, the global models
show a sharp increase in southwesterly shear, which should cause the
cyclone to begin weakening.   The NHC intensity forecast lies
between the SHIPS model and the intensity model consensus.

The storm has been moving slowly west-southwestward during the past
6 to 12 hours.  A mid-level ridge located to the north and northwest
of Vance is expected to steer the cyclone west-southwestward to
westward during the next day or two.  After that time, a gradual
turn to the north and then northeast is forecast as the ridge
weakens and shifts eastward in response to an approaching large
trough.  Although the models are in agreement in the large-scale
steering pattern, there is a fair amount of spread in where Vance
turns northward.  The NHC track forecast has been adjusted a little
to the left of the previous one for the first 72 hours to be in
better agreement with the latest guidance.

FORECAST POSITIONS AND MAX WINDS

INIT  31/0300Z 10.8N 101.3W   40 KT  45 MPH
 12H  31/1200Z 10.4N 102.0W   45 KT  50 MPH
 24H  01/0000Z 10.0N 103.3W   50 KT  60 MPH
 36H  01/1200Z  9.9N 105.1W   50 KT  60 MPH
 48H  02/0000Z 10.4N 107.0W   55 KT  65 MPH
 72H  03/0000Z 12.9N 110.2W   70 KT  80 MPH
 96H  04/0000Z 17.1N 110.4W   65 KT  75 MPH
120H  05/0000Z 20.5N 107.5W   45 KT  50 MPH

$$
Forecaster Cangialosi

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