Hurricane VANCE

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HURRICANE VANCE DISCUSSION NUMBER  16
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP212014
700 PM PST SUN NOV 02 2014

Vance has displayed a pinhole eye surrounded by very cold cloud tops
both in microwave imagery and sporadically in visible/infrared
imagery.  Subjective Dvorak estimates from SAB and TAFB along with a
2124Z AMSU objective analysis from CIMSS indicates an intensity of
90 kt.  The combination of very low vertical shear, quite moist and
unstable thermodynamics, warm SSTs, and large upper-level divergence
have contributed toward Vance's rapid intensification during the
last 24 hours, during which time the maximum winds have doubled.
Vince has about 12 hours of conducive conditions remaining before a
high amplitude upper- to mid-level trough currently west of Baja
California begins to adversely affect the tropical cyclone. Vertical
shear should quickly ramp up while the moisture, convective
instability, and upper-level divergence drop during the next two
days.  Vance is predicted to peak in intensity shortly followed by
rapid weakening, most similar to the LGEM and SHIPS statistical
models during the next 24 hours and to the IVCN multi-model
consensus thereafter.  This forecast is higher than that in the
previous advisory due to the stronger initial intensity, but lower
at days 2 and 3.

Vance is moving 310 degrees at 15 kt, as it is being advected around
the periphery of a deep-layer ridge to its northeast.  As the
aforementioned trough digs southward, Vance should undergo
recurvature beginning in about a day, at the very low latitude of
about 18 North.  The tropical cyclone should then turn toward the
north-northeast on Tuesday and start approaching southwestern
Mexico.  However, the shear should become so severe that the
tropical cyclone is likely to decouple in about three days with the
remnant low not quite reaching the coast. The NHC official track
prediction is based upon the TVCE multi-model consensus, and is
faster than the previous advisory but not as far northeast as the
GFS-ECMWF combination.  An alternative scenario is that Vance
reaches the southwestern Mexican coast as a tropical storm in about
three days, as seen in the deterministic ECMWF model run.  However,
given the quite hostile vertical shear conditions expected, and that
the ECMWF solution appears to be an outlier compared to its ensemble
members, this is not considered to be likely at this time.

FORECAST POSITIONS AND MAX WINDS

INIT  03/0300Z 13.7N 109.6W   90 KT 105 MPH
 12H  03/1200Z 15.2N 110.6W  100 KT 115 MPH
 24H  04/0000Z 17.1N 110.8W   90 KT 105 MPH
 36H  04/1200Z 18.7N 110.1W   70 KT  80 MPH
 48H  05/0000Z 20.4N 108.8W   50 KT  60 MPH
 72H  06/0000Z 23.5N 107.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  07/0000Z...DISSIPATED

$$
Forecaster Landsea

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