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Tropical Storm VANCE (Text)

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TROPICAL STORM VANCE DISCUSSION NUMBER  23
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP212014
100 PM PST TUE NOV 04 2014

The organization of Vance has decreased significantly over the past
several hours due to the effects of 50-60 kt of vertical wind
shear. The low-level center is now exposed to the southwest of
the main convective mass, and the convection has decreased in both
coverage and intensity.  The initial intensity is lowered to 55 kt,
and this again could be a little generous.

The initial motion is 030/12.  The guidance has trended eastward and
faster since the last advisory, and the dynamical models now
forecast the cyclone to make landfall over mainland Mexico in 18-24
hours.  The new forecast track lies a little to the east of the
previous track, but is west of, and slower than, the consensus
models.

Continuing strong shear should cause additional rapid weakening.
The majority of the guidance forecasts Vance to weaken below
tropical-storm strength before landfall, and the new intensity
forecast follows that scenario.  However, given the uncertainties in
intensity prediction it remains prudent to have a tropical storm
watch for portions of the coast of Mexico.  After landfall, Vance
is expected to dissipate over the mountains of northwestern Mexico.

Moisture from Vance and its remnants is spreading northeastward
across Mexico and into the south-central United States.  This is
producing heavy rains over portions of these areas which should
continue through Thursday or Friday.


FORECAST POSITIONS AND MAX WINDS

INIT  04/2100Z 20.4N 108.6W   55 KT  65 MPH
 12H  05/0600Z 22.1N 107.8W   40 KT  45 MPH
 24H  05/1800Z 24.4N 106.9W   25 KT  30 MPH...INLAND
 36H  06/0600Z 26.5N 106.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 48H  06/1800Z...DISSIPATED

$$
Forecaster Beven

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