000
WTPZ41 KNHC 302034
TCDEP1

TROPICAL STORM VANCE DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP212014
200 PM PDT THU OCT 30 2014

Visible satellite images show that the center of the cyclone
remains near the southwestern edge of the deep convection.  Still,
the convective organization has improved from a few hours ago, with
a distinct band on the northeast side of the system.  Dvorak
estimates and scatterometer data support an initial wind speed of 35
kt for this advisory.  Vance is the 20th named storm of the eastern
North Pacific hurricane season, the most number of named storms in
the basin since 1992.

The scatterometer data suggests that Vance is now moving about
260/4.  A southwestward motion is expected tomorrow as a ridge
builds to the north of the cyclone.  The storm should turn westward
and west-northwestward by 72 hours while it moves across the
southwestern periphery of the ridge.  Vance will likely turn
northward or north-northeastward at long range ahead of a
mid-latitude trough diving over Baja California into the eastern
Pacific.  While there is broad agreement on the general synoptic
pattern, the models have a stronger ridge than the last cycle,
leading to the storm moving farther to the west and south.  This
shift in the steering has led to a slower solution at long range
by almost every reliable model.  The official NHC prediction is
shifted westward and southward throughout the forecast period, and
further adjustments could be required on the next advisory if model
trends continue.

Although Vance is expected to remain over warm water for the next
several days, it is currently struggling with dry air entrainment
and southwesterly shear.  Most of the models respond to this
environment by showing little significant intensity change during
the next 24 hours, so the official forecast will follow suit.
After that time, the global models continue to show reduced shear,
with an increase in low- to mid-level moisture.  These conditions
should allow for Vance to become a hurricane in a few days,
although guidance is not in particularly good agreement on this
scenario.  At long range, there is high uncertainty in the
intensity forecast, with the models generally showing more shear
than the last cycle.  Thus the intensity prediction is lowered some
from the previous NHC forecast, although it remains on the higher
side of the guidance.

FORECAST POSITIONS AND MAX WINDS

INIT  30/2100Z 11.0N 101.0W   35 KT  40 MPH
 12H  31/0600Z 10.6N 101.6W   40 KT  45 MPH
 24H  31/1800Z 10.1N 102.5W   40 KT  45 MPH
 36H  01/0600Z  9.9N 104.0W   45 KT  50 MPH
 48H  01/1800Z 10.1N 105.9W   50 KT  60 MPH
 72H  02/1800Z 12.0N 109.6W   65 KT  75 MPH
 96H  03/1800Z 16.0N 110.5W   70 KT  80 MPH
120H  04/1800Z 20.0N 108.5W   60 KT  70 MPH

$$
Forecaster Blake