Tropical Weather Discussion
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172
AXPZ20 KNHC 181535
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1344 UTC Sat Nov 18 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
1530 UTC.

...SPECIAL FEATURE...

Gulf of Tehuantepec Gale Warning: Pulses of strong northerly
drainage flow will diminish to 20 kt or less today, with winds
becoming light and variable in the afternoon hours. Strong to
near gale-force conditions will develop late tonight in the wake
of a cold front in the Gulf of Mexico, and then quickly increase
to gale-force on Sun morning. These conditions will continue
through Mon morning. Seas will build to a max of 15 ft downstream
of the gulf waters near 14N95.5W on Sun night. Winds will
diminish to 20 kt or less around sunrise on Tue.

INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

The monsoon trough is from 09N83W to 09N103W. ITCZ extends from
09N103W to 11N140W. Scattered moderate convection is within 255
nm on either side of the ITCZ.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

See the Special Features section for information about the Gulf
of Tehuantepec Gale Warning.

A NW to SE orientated ridge just beyond 250 nm seaward will
maintain moderate to locally fresh NW flow W of Baja Peninsula
through sunrise on Sun when the pressure gradient will relax,
supporting moderate NW flow through sunrise on Mon. Light N winds
winds then expected through sunrise on Thu.

Gulf of California: Light and variable winds at sunrise this
morning will quickly become northerly this morning with strong N
winds developing across the gulf waters N of 30N by early this
afternoon. These strong NW winds will shift S across the central
gulf waters tonight surrounded by fresh NW flow elsewhere.
Little change then expected through Sun morning when the
pressure gradient will relax with moderate NW flow forecast
across the entire gulf waters by sunrise on Mon, becoming light
northerly flow Mon night.

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

Gulf of Papagayo: Moderate to locally fresh NE drainage winds
are forecast during the overnight hours through the middle of
next week with seas building to 5 ft downstream near 10N87W.

Light and variable winds, and 3 to 5 ft seas, are expected
elsewhere to the N of 09N, while moderate to locally fresh
southerly winds, and 4 to 7 ft seas, are forecast S of 09N
through the middle of next week.

REMAINDER OF THE AREA...

A NE to SW aligned ridge builds from 32N124W to beyond 20N140W.
Fresh to locally strong southerly flow will develop across the
waters N of 26N W of 134W tonight, with seas building to 9 ft.
Expect strong southerly winds N of the ridge, generally across
the waters N of 23N W of 137W on Sun through Tue, with seas
building 8 to 12 ft. The associated cold front will arrive at
32N140W late Wed, with seas building 12 to 18 ft W of the front
through Thu.

Moderate to locally fresh anticyclonic flow expected across the
tropics N of the ITCZ and W of 120W through the middle of next
week with seas building to 8 ft.

$$
ERA




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