Tropical Weather Discussion
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000
AXPZ20 KNHC 222131
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2115 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 1800 UTC surface analysis and satellite imagery through
2100 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 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 to 20 ft by midweek. The gale force winds are likely to
persist into early Thursday morning before diminishing to fresh
to strong for the remainder of Thursday, then to 20 kt or less by
Friday.

...TROPICAL WAVES...

The axis of a tropical wave is along 103W from 08N to 15N moving
W at around 10 kt. Scattered moderate and isolated strong
convection is noted from 06N to 10N between 98W and 104W.

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

The monsoon trough axis extends from 11N84W to 08N100W to
09N115W to 08N125W. The intertropical convergence zone axis
extends from 08N125W to 09N140W. Scattered moderate and isolated
strong convection is from 08N to 12N between 120W and 125W, and
also from 06N to 12N W of 134W.

...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 with the
highest seas measured N of Cabo San Lazaro. Concurrent
scatterometer satellite passes indicated that winds have
diminished to moderate levels. The swell is forecast to decay
to less than 12 ft through this evening, then subside further
to less than 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
through early Monday, 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 the week.

REMAINDER OF THE AREA...

A set of large NW swell with seas near 12 ft will continue to
propagate SE while gradually subsiding. A new reinforcing set of
NW swell will arrive at 30N140W on Monday, however peak seas will
be less than the previous set. Seas will then subside, to less
than 8 ft, by mid week with tranquil marine conditions expected
by the end of the week.

$$
Lewitsky



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