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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 172112
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2112 UTC Wed Jan 17 2018

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: Strong high pressure continues
to build southward across eastern Mexico and the western Gulf of
Mexico supporting a tight pressure gradient across the area. 
Gale force winds will continue to pulse from minimal to strong 
gale force, with the strongest winds expected during the late 
night and early morning hours. Winds are expected to gradually 
diminish below gale force by Friday afternoon. The resultant 
plume of northerly swell will continue to propagate well 
southward of the offshore Gulf of Tehuantepec waters, mixing with
long period NW swell. Seas will be up to 14 to 19 ft during the 
strongest winds, gradually subsiding by the end of the week as 
the winds diminish.

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

A surface trough axis extends from 08N77W to low pressure near 
06N79W to 06N84W to 05N93W. The intertropical convergence zone 
axis extends from 05N93W to 07N106W to 06N115W to 09N135W, then
resumes from 09N139W to 09N140W. Scattered moderate convection is
within 120 nm in the SW semicircle of the low, and within 45 nm 
either side of the ITCZ axis between 104W and 115W. Scattered 
moderate and isolated strong convection is within an area bounded
by 12N140W to 16N128W to 11N115W to 04N115W to 04N126W to 
08N133W to 06N140W to 12N140W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Please see the special features section for information about 
the ongoing gale warning in the offshore waters of the Gulf of 
Tehuantepec.

In the Gulf of California, light to moderate NW flow is forecast
across across the entire gulf waters through Friday afternoon.
Winds will become southerly Friday evening ahead of a cold front,
increasing to fresh to strong in the northern gulf Friday night,
then shifting to NW to N behind the front. The front will
dissipate while it moves southward across the gulf during the day
Saturday with mainly moderate to fresh northerly flow in its wake
for the end of the weekend, except increasing to fresh to strong
in the central and southern Gulf Sunday afternoon and night as
the pressure gradient tightens across that area.

Elsewhere across the offshore waters of Mexico, large NW swell 
continues to propagate SE across the waters, with seas of 8-12 ft
prevailing, except 5-8 ft between 98W and 105W. The large swell
is generating high and powerful surf along the coasts and outer 
reefs of the Baja California peninsula and mainland Mexico which
will continue this evening, with coastal flooding also possible.
Another pulse of NW swell will reach the offshore waters off 
Baja California Norte Thursday night. Seas will peak near 13-15 
ft by Friday, while seas of 12 ft or greater will spread across 
the offshore waters off the entire length of the Baja Peninsula 
through the upcoming weekend.

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

Fresh NE gap winds winds will pulse to strong each night and
early morning across the Gulf of Papagayo through Saturday
morning, diminishing thereafter. Winds will also pulse to fresh
to strong offshore of other Central America gulfs and gap wind
areas tonight into early Thursday. Elsewhere, mainly light to 
gentle offshore winds will prevail N of 09N, with light to gentle
southerly flow S of 09N. NW swell originating from a gale force
wind event in the Gulf of Tehuantepec along with longer period 
NW swell will arrive across the area waters Thursday and Friday, 
building seas offshore to 5-7 ft.

REMAINDER OF THE AREA...

Large, long period NW swell continues to propagate SE across the 
forecast waters, with seas of 8 to 14 ft across the waters W of
95W-100W. A weakening cold front currently W of the area will
move SE of 30N140W by early Thursday, then will get reinforced by
building high pressure Thursday evening. Winds W of the
reinforced front will increase to fresh to strong Thursday
evening, with fresh to strong trades gradually spreading across 
the waters N of 10N W of 110W during the upcoming weekend while 
the front also dissipates across the N central waters.

$$
Lewitsky