000
WTPZ42 KNHC 160233
TCDEP2

Tropical Storm Tara Discussion Number   7
NWS National Hurricane Center Miami FL       EP222018
1000 PM CDT Mon Oct 15 2018

A high-resolution GCOM microwave pass from 2030 UTC revealed that
Tara remains a tiny tropical cyclone, but it has also developed
tightly coiled convective bands which could not be observed in
convectional satellite imagery alone.  With this improved
structure, TAFB's Dvorak estimate, the ADT estimate, and SATCON all
increased to 55 kt, and that is set as the initial intensity on
this advisory.

The GCOM pass also indicated that Tara's center has moved closer to
the coast of Mexico, albeit slowly, and the initial motion estimate
is northwestward, or 325/2 kt.  Tara's future track has become less
clear, and the NHC track forecast is of very low confidence.  The
most reliable global models (the GFS, ECMWF, and UKMET models)
either bring Tara inland over Mexico or have the system dissipating
just offshore during the next couple of days, and as a result, there
were very few model trackers to follow when making the forecast.
Using what little vorticity can be followed in the global model
fields, the new NHC track forecast has been adjusted northward,
closer to the coast of Mexico.  This new forecast has Tara's small
tropical-storm-force wind field grazing the coast of Colima and
Jalisco within the next 12-24 hours, and since there's also a
possibility that the center will move inland, the government of
Mexico has upgraded the Tropical Storm Watch from Manzanillo to Cabo
Corrientes to a Tropical Storm Warning.

Due to Tara's small size, continued intensification is possible.
However, moderate southeasterly shear is forecast to continue for
the next 24 hours, and as a result, the NHC forecast holds the
intensity at 55 kt for the next day or two.  After 24 hours, the
shear vector begins to turn more southerly and southwesterly, which
will likely allow drier air to entrain into the circulation.  And,
that all assumes that Tara will not have moved inland by that time.
Based on these environmental factors, and the fact that the models
are now showing the circulation dissipating much sooner, the
new NHC intensity forecast is lower than the previous forecast at
48 hours and beyond, showing Tara becoming a remnant low by day 4
and dissipating by day 5.

Heavy rainfall will continue to be a threat along the coast of
southwestern Mexico due to the system's slow motion, and
life-threatening flash flooding will be possible in mountainous
areas.


FORECAST POSITIONS AND MAX WINDS

INIT  16/0300Z 18.4N 104.6W   55 KT  65 MPH
 12H  16/1200Z 18.7N 104.8W   55 KT  65 MPH
 24H  17/0000Z 19.0N 105.4W   55 KT  65 MPH
 36H  17/1200Z 19.1N 106.0W   55 KT  65 MPH
 48H  18/0000Z 19.1N 106.4W   50 KT  60 MPH
 72H  19/0000Z 18.9N 107.4W   40 KT  45 MPH
 96H  20/0000Z 18.5N 107.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  21/0000Z...DISSIPATED

$$
Forecaster Berg