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Tropical Storm Willa Discussion Number   3
NWS National Hurricane Center Miami FL       EP242018
400 PM CDT Sat Oct 20 2018

Willa appears to be wrapping up quickly, and the low-level center
is now embedded beneath a ragged central dense overcast.  ASCAT data
from several hours ago indicated winds were as high as 40 kt, but
more recent satellite estimates support an intensity between 45-55
kt, and the maximum winds are set at 50 kt for this advisory.

Willa has turned west-northwestward and slowed down, and the
initial motion is estimated to be 295/5 kt.  The cyclone is
forecast to recurve around the western edge of a mid-level ridge
that lies over Mexico during the next few days, and then accelerate
northeastward into mainland Mexico by days 4 and 5 ahead of a broad
mid-latitude trough.  Compared to previous model runs, the new
track guidance has sped up significantly and also now shows a
sharper recurvature, both of which suggest that Willa's hazards
could reach the coast of Mexico sooner than originally thought.
The GFS and ECMWF remain the fastest of the models, and although
the updated NHC track forecast trends in their direction, it hangs
back a bit to give some weight to the HWRF, HCCA, and Florida State
Superensemble.  Even with that consideration, the new forecast does
bring Willa to the coast sooner than before.

The satellite signature suggests that the storm is organizing
quickly and is probably in the beginning stages of rapid
intensification (RI).  The RI indices are even higher this
afternoon than they were this morning, and incredibly, the HWRF,
SHIPS, HCCA, and Florida State Superensemble all bring Willa near or
at major hurricane intensity in 36 hours.  The NHC forecast follows
those models' lead and indicates significant strengthening over the
next couple of days.  A peak in intensity is likely to occur
between 48-72 hours, followed by some weakening due to lower
oceanic heat content and increasing vertical shear.  Despite the
expected weakening, Willa is expected to reach the coast of
west-central mainland Mexico as a hurricane in about 4 days.


FORECAST POSITIONS AND MAX WINDS

INIT  20/2100Z 15.2N 105.8W   50 KT  60 MPH
 12H  21/0600Z 15.5N 106.3W   65 KT  75 MPH
 24H  21/1800Z 16.1N 106.9W   85 KT 100 MPH
 36H  22/0600Z 16.8N 107.4W  105 KT 120 MPH
 48H  22/1800Z 17.6N 107.8W  110 KT 125 MPH
 72H  23/1800Z 19.1N 108.1W  100 KT 115 MPH
 96H  24/1800Z 22.0N 106.5W   80 KT  90 MPH
120H  25/1800Z 24.5N 103.5W   40 KT  45 MPH...INLAND

$$
Forecaster Berg

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