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Tropical Storm Xavier Discussion Number   8
NWS National Hurricane Center Miami FL       EP252018
900 AM CST Sun Nov 04 2018

Xavier surprised us a little bit this morning when most of its deep
convection was sheared away, revealing that the center of
circulation was farther northeast than previously estimated.
A 1234 UTC SSMIS microwave pass showed that the mid-level center was
moving onshore the coast of Mexico with the deep convection, but the
low-level center remains well offshore.  Some new convection has
recently developed near the low-level center, as well as in a band
to the northwest.  Objective and subjective Dvorak T-numbers have
begun to fall given the decrease in deep convection, and Xavier's
initial intensity is therefore lowered to 45 kt.

Various shear calculations indicate that Xavier is now being
affected by 20-25 kt of southwesterly shear, which is expected to
increase further during the next 24 hours.  In addition, GOES-16
low-level water vapor imagery shows that dry air has infiltrated
Xavier's circulation.  The shear and dry air should make it harder
and harder for Xavier to maintain organized deep convection, and
the cyclone is therefore forecast to steadily weaken and degenerate
into a remnant low in about 48 hours.  The NHC intensity forecast
lies within the tightly packed intensity guidance envelope and is
generally an update of the previous forecast.  The remnant low of
Xavier is likely to dissipate by day 5.

Xavier's surface center appears to have been tugged northeastward by
deep convection over the past 12 hours, which suggests a
longer-term motion of 020/9 kt.  Now that most of the convection
has been sheared away, however, the surface center seems to have
slowed down, and the advisory motion is 005/5 kt.  The track
guidance continues to insist that Xavier will turn northwestward
and west-northwestward during the next 24 hours as its circulation
becomes shallower and is steered by lower-level easterly winds.
The UKMET is the notable outlier, keeping Xavier as a deeper
circulation and moving it more northward, closer to the coast of
Mexico.  The new NHC track forecast is generally between the
multi-model consensus aids (near the northern side of the guidance
envelope) and the GFS/ECMWF solutions (near the southern side), and
it lies north of the previous forecast to account for the adjusted
initial position.

Large swells, locally heavy rainfall, and gusty winds could affect
portions of the coast of southwestern Mexico during the next day or
two, even with the center forecast to remain offshore.


FORECAST POSITIONS AND MAX WINDS

INIT  04/1500Z 17.6N 105.3W   45 KT  50 MPH
 12H  05/0000Z 18.1N 105.8W   40 KT  45 MPH
 24H  05/1200Z 18.5N 106.7W   35 KT  40 MPH
 36H  06/0000Z 18.8N 107.8W   30 KT  35 MPH
 48H  06/1200Z 19.1N 109.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  07/1200Z 19.3N 111.6W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  08/1200Z 19.2N 113.8W   15 KT  15 MPH...POST-TROP/REMNT LOW
120H  09/1200Z...DISSIPATED

$$
Forecaster Berg

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