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Eastern North Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 102221
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2020 UTC Sun Dec 10 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
2130 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Storm Warning: A very tight pressure gradient
across the Isthmus of Tehuantepec remains supported by 1036 mb 
high pres over N central Mexico will support storm force winds 
of 40-50 kt across the Gulf of Tehuantepec until early Mon 
morning, with seas in the 14-22 ft range. A large area of gale 
force winds of 30-40 kt surrounds the storm force winds within 
120 nm either side of a line from 16N95W to 14N96W to 12N98W, 
with corresponding seas in the 12-19 ft range. Fresh to strong 
NE-E winds extend downstream from the gulf to near 11N and 102W,
where seas run 8 to 11 ft in NE swell. Seas 8 ft or greater are 
propagating well away from the Gulf to near 105W this evening, 
and will propagate even farther W to near 110W on Monday. The 
ongoing storm conditions are forecast to weaken to a strong gale 
by early this afternoon and continue into early Monday before 
weakening further to minimal gale force early on Tuesday. These 
conditions are forecast to continue through Wednesday night of 
the upcoming week.

Gulf of Papagayo Gale Warning: The pressure difference between
a very tight packing of isobars pressing southward across the 
northern portion of Central America from 1036 mb high pres over 
N central Mexico and broad low pres over the remainder of 
Central America and the SW Caribbean Sea has induced NE gale 
force winds of 30-35 kt over the Gulf of Papagayo. N-NE winds of
20-30 kt are elsewhere downstream from the gale force winds over
an area from 07N-11N between 85W-88W. The pres gradient will 
loosen enough to allow for these gale conditions to diminish to 
strong to near gale force NE winds late Monday night and to 
strong NE winds Tuesday. Seas of 8-10 ft will propagate to the SW
well away from the gale force wind area reaching from 05N-11N 
between 86W-90W early on Monday, and from 04N-10N between 86W-91W
early on Tuesday.

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

The Monsoon Trough axis extends from western Colombia at 09N74W 
to 07N80W to 08N86W to 07N96W to 10N115W to 07N127W to 07N136W.
The ITCZ continues from 07N136W to beyond 08N140W. Scattered 
moderate and isolated strong convection is present from 06N to 
09N between 77W and 87W...from 08N to 10N between 113W and 118W 
and from 06N to 09N between 124W and 134W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Gulf of Tehuantepec: Please see Special Features section above 
for details on an ongoing storm event. 

High pressure over the Great Basin will remain strong enough to 
maintain fresh to strong northerly winds over the northern Gulf 
of California this evening before it weakens. N-NE winds 
funneling through the Baja California peninsula into the Pacific 
waters have diminished to 15-20 kt. Seas will subside below 8 ft 
off the coast of Baja California tonight. Elsewhere gentle to 
moderate winds and 4-6 ft seas will persist through next week.

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

Gulf of Papagayo: Please, see Special Features section above 
for details on an ongoing gale event. 

Strong high pressure ridging southeastward across northern 
central America is combining with low pressure over the 
remainder of Central America to generate strong to gale force NE
winds through the Gulf of Papagayo and nearby waters. Large NE 
swell from a Tehuantepec gap wind event will spread across the 
offshore waters of Guatemala and El Salvador through Mon. 
Localized gap pulses of strong NE winds are possible off the 
coast of El Salvador and Guatemala, including Gulf of Fonseca 
beginning early today.

REMAINDER OF THE AREA...

A cold front is crossing the NW corner of the area. A tight 
pressure gradient between the front and high pressure over the 
northern waters is bringing strong S to SW winds to area N of a 
line from 32N134W to 29N140W along with seas of 10-14 ft in NW 
swell. The cold front will reach a position from near 32N136W to
27N140W this evening as winds subside to 20 kt or less. Seas will
run 8-15 ft in NW swell N of a line from 32N132W to 24N140W. 
This front will begin to weaken by early tonight from near 
32N136W to 27N140W, with winds on either side of it becoming 
15-20 kt. Seas of 11-15 ft in NW swell are expected W of the 
front while seas of 8-10 ft are expected within 180 nm SE of the 
front at that time. The front will dissipate by late Monday 
night, however, long period NW swell will maintain seas of 8-11 
ft W of a line from 32N122W to 13N124W to 08N140W. The swell 
will gradually decay through Wed morning, with seas of 8-10 ft 
expected W of a line from 20N121W to 00N135W. The pressure 
difference between a trough near 136W and the high pressure over 
the northern waters is forecast to result in strong NE-E winds 
beginning late Monday night from 13N- 18N, and to the W of 129W 
along with seas of 8-10 ft. This area of strong winds will shift 
to W of 130W by early on Tuesday, then diminish to 15-20 kt late
Tuesday.

$$
CAM

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Page last modified: Sunday, 10-Dec-2017 22:21:54 UTC