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Tropical Storm Sergio Discussion Number  43
NWS National Hurricane Center Miami FL       EP212018
800 PM PDT Tue Oct 09 2018

The GOES-15 satellite presentation and an earlier ATMS polar
orbiter microwave image revealed little change in Sergio's cloud
pattern during the past 6 hours.  Deep convection persists in the
north semicircle in the form of a rather large curved band while the
southern portion is comprised of fragmented bands.  A blend of the
Dvorak satellite classifications, which haven't changed much,
supports holding the initial intensity at 60 kt for this advisory.

Very little change in strength is forecast during the next 6-12
hours, as Sergio traverses relatively warm oceanic temperatures and
remains in a low shear surrounding environment.  Afterward,
statistical and dynamical intensity guidance shows weakening through
the 48 period, or prior to landfall, as the cyclone moves over
cooler waters and into a region of increasing southwesterly vertical
shear.  Over the weekend, after quickly moving over Baja California
Sur, Sergio will weaken further over the state of Sonora in
northwestern Mexico, degenerate into a remnant low by day 4, and
dissipate over the Southern Plains of the United States.

The initial motion is estimated to be east-northeastward, or 060/10
kt, within the deep-layer southwesterly flow produced by a
mid-latitude trough stretching southwestward over the eastern
Pacific from the southwestern United States.  Sergio should continue
to accelerate toward the east-northeast or northeast over the next
few days, moving over Baja California Sur on Friday, and over the
Gulf of California and into northwestern Mexico Friday night and
Saturday.

The primary threat associated with Sergio and its remnants will
likely be life-threatening flash flooding and mudslides within
mountainous terrain in the Mexico state of Sonora, the U.S.
Southern Plains and the Ozarks through the weekend.  For more
information about this potential hazard, see products from the
Weather Prediction Center and your local weather forecast office.


FORECAST POSITIONS AND MAX WINDS

INIT  10/0300Z 17.5N 125.6W   60 KT  70 MPH
 12H  10/1200Z 18.2N 124.2W   60 KT  70 MPH
 24H  11/0000Z 19.6N 121.9W   55 KT  65 MPH
 36H  11/1200Z 21.7N 119.3W   50 KT  60 MPH
 48H  12/0000Z 24.1N 116.5W   50 KT  60 MPH
 72H  13/0000Z 28.7N 110.0W   35 KT  40 MPH...INLAND
 96H  14/0000Z 33.0N 101.8W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  15/0000Z...DISSIPATED

$$
Forecaster Roberts

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