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Tropical Storm Xavier Discussion Number   9
NWS National Hurricane Center Miami FL       EP252018
300 PM CST Sun Nov 04 2018

After being sheared off this morning, deep convection has
redeveloped and persisted over Xavier's center of circulation.
Dvorak Current Intensity numbers from TAFB and SAB remain 3.0, and
the latest UW-CIMSS SATCON estimate is 43 kt.  The initial intensity
therefore remains 45 kt.  Although shear analyses indicate that
about 25 kt of southwesterly shear is affecting Xavier, an
upper-level trough in the vicinity appears to be producing a decent
amount of divergence aloft to support the ongoing convection.  The
global models show that trough dissipating and the upper flow
becoming unidirectional within 12 hours, which should cut off the
divergence and allow the adverse effects of shear and dry air to
take over.  As a result, gradual weakening is expected during the
next couple of days, and Xavier may cease to produce organized deep
convection (and thus become a remnant low) in 36-48 hours.  The
remnant low should dissipate by day 4, if not sooner.  The updated
NHC intensity forecast is conservative, following continuity from
the previous forecast and lying near the upper bound of the
intensity models.

Xavier's motion still appears to be slowly northward, or 350/5 kt.
The global models, most of which assume that Xavier will become a
shallow system soon, show the cyclone turning northwestward and
west-northwestward during the next 24 hours.  While this seems
reasonable, as long as Xavier maintains vertical integrity, it will
likely continue moving closer to the right side of the guidance
envelope.  With the assumption that deep convection won't dissipate
right away, the NHC track forecast is to the right of the consensus
aids, close to the ECMWF solution, during the first 24 hours.
After 24 hours, it remains close to the TVCN multi-model consensus.

A 1600 UTC ASCAT pass indicated that Xavier's tropical-storm-force
wind field on the east side was larger than previously estimated,
with those winds lying near the coast of southwestern Mexico.  As a
result, the government of Mexico issued a Tropical Storm Warning for
a portion of the coasts of Michoacan, Colima, and Jalisco.  Locally
heavy rainfall and large swells are also likely to affect the coast
of southwestern Mexico during the next day or two.


FORECAST POSITIONS AND MAX WINDS

INIT  04/2100Z 18.1N 105.5W   45 KT  50 MPH
 12H  05/0600Z 18.7N 106.0W   40 KT  45 MPH
 24H  05/1800Z 19.2N 107.1W   35 KT  40 MPH
 36H  06/0600Z 19.5N 108.2W   30 KT  35 MPH
 48H  06/1800Z 19.6N 109.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  07/1800Z 19.4N 111.8W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  08/1800Z 19.0N 114.0W   15 KT  15 MPH...POST-TROP/REMNT LOW
120H  09/1800Z...DISSIPATED

$$
Forecaster Berg

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