Tropical Weather Discussion
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000
AXPZ20 KNHC 221547
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1547 UTC Sun Oct 22 2017

Tropical Weather Discussion for the eastern Pacific Ocean from
the Equator to 32N, east of 140W. The following information is
based on satellite imagery, weather observations, radar, and
meteorological analysis.

Based on 1200 UTC surface analysis and satellite imagery through
1500 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: High pressure building
southward across eastern Mexico in the wake of a cold front will
help tighten the pressure gradient over the area. In response to
the tighter pressure gradient, fresh to strong northerly flow
will funnel through the Chivela pass into the Gulf of
Tehuantepec starting late tonight. Winds will further increase
to gale force by early Monday morning as the cold front moves
through the western Gulf of Mexico. Winds may even approach
minimal storm force by early Wednesday, with seas building to up
to 18 ft by midweek.

...TROPICAL WAVES...

The axis of a tropical wave is near 102W from 07N to 15N moving
W at around 10 kt. Scattered moderate convection is noted from
07N to 10N between 98W and 101W.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

The monsoon trough extends from 11N85W to 08N120W. The ITCZ
extends from 08N120W to 09N140W. Scattered moderate convection
was noted from 08N to 10N between 120W and 125W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Please see the special features section above for information on
a developing gale event in the Gulf of Tehuantepec.

Recent altimeter satellite passes indicated seas of 8 to 14 ft
over much of the area offshore of Baja California, north of Cabo
San Lazaro. Concurrent scatterometer satellite passes indicated
strong northerly winds active in this area have diminished a bit,
leaving the main component of the seas long period northerly
swell. The swell is expected to decay below 12 ft through this
afternoon, then subside further to below 8 ft off Baja California
Sur and within 200 nm of the coast of Baja California Norte
through late Monday. Looking ahead, gentle breezes associated
with a weak pressure pattern along with slight to moderate seas
will prevail by late week.

High pressure over the Great Basin region of the western United
States has strengthened winds over the Gulf of California. Fresh
to strong winds are expected to continue through Tuesday, before
diminishing as the area of high pressure shifts eastward and the
pressure gradient weakens. Winds will be the strongest tonight
through Monday when seas will peak around 8 ft.

OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...

Gentle to moderate winds will prevail over the forecast area the
rest of the weekend, increasing to moderate to fresh S of the
monsoon trough by Monday afternoon. NW swell originating from the
Gulf of Tehuantepec will propagate into the offshore waters of
Guatemala and El Salvador by the middle of next week.

REMAINDER OF THE AREA...

A set of large NW swell with seas near 15 ft will continue to
propagate SE while gradually subsiding. Seas will subside to
less than 12 ft this afternoon. Seas associated to this swell
are expected to further subside, to less than 8 ft, by mid week.

$$
Christensen



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