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Tropical Storm Mario Discussion Number   3
NWS National Hurricane Center Miami FL       EP142019
900 PM MDT Tue Sep 17 2019

Mario's center was partially exposed after the release of the
previous advisory, but it is now covered by a new convective burst.
The convection itself remains somewhat lopsided, favoring the
southwestern quadrant due to strong upper-level easterly winds
emanating away from the larger Tropical Storm Lorena to the east.
Since subjective and objective satellite intensity estimates range
from 30-40 kt, the initial intensity remains 35 kt on this advisory.

The initial motion remains northwestward, or 325/8 kt.  A mid-level
ridge over Mexico should keep the cyclone on its northwestward
trajectory for the next 2 days, but since the ridge retreats
eastward a bit, Mario's forward motion is expected to decrease
significantly during that time.  By day 3, Mario and Lorena may get
close enough to one another to cause Mario to almost stall.  After
day 3, Mario's track will mostly depend on Lorena's future, and
there is significant model spread on days 4 and 5.  The GFS has a
stronger Lorena moving up near the Baja California peninsula, which
pulls Mario farther toward the north and east.  The ECMWF, on the
other hand, dissipates Lorena near west-central Mexico, which
allows Mario continue on a northwestward heading.  For now, the
official forecast splits the difference and closely follows the
multi-model consensus aids and the HCCA model.

Easterly to northeasterly shear is likely to continue over Mario
during the next day or two, so only gradual strengthening is
expected during that time.  Vertical shear may decrease around the
time that Mario stalls, and at that point the system is forecast to
become a hurricane.  Some weakening is anticipated by the end of
the forecast period due to an increase in shear.  The updated NHC
intensity forecast is only slightly lower than the previous one
based on the latest guidance.  It should be noted that there is
greater-than-normal uncertainty in this forecast since it is not
known how much Mario and Lorena will interact in the coming days.


FORECAST POSITIONS AND MAX WINDS

INIT  18/0300Z 13.2N 109.3W   35 KT  40 MPH
 12H  18/1200Z 14.2N 110.5W   40 KT  45 MPH
 24H  19/0000Z 15.5N 112.0W   50 KT  60 MPH
 36H  19/1200Z 16.3N 113.0W   55 KT  65 MPH
 48H  20/0000Z 16.7N 113.5W   60 KT  70 MPH
 72H  21/0000Z 16.9N 113.8W   65 KT  75 MPH
 96H  22/0000Z 17.5N 114.3W   65 KT  75 MPH
120H  23/0000Z 19.4N 115.1W   55 KT  65 MPH

$$
Forecaster Berg

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