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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 120913
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Tue Dec 12 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 0600 UTC surface analysis and satellite imagery through 
0900 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: A tight pressure gradient 
continues across the Isthmus of Tehuantepec in southern Mexico. 
This gradient will maintain gale force winds in the range of 30-
40 kt in the Gulf of Tehuantepec today, then diminish to minimal 
gale by early Wed, becoming 30 kt on Wed. Max seas of 16-17 ft 
will subside to 13-15 ft later today. Fresh to strong NE-E winds 
extend downstream from the gulf to near 12N98W. A large area of 
fresh NE-E winds is evident from scatterometer data from 02N-15N 
between 90W-110W, with seas of 8-12 ft in mixed NE and SW swell. 
This area will gradually shrink in coverage through Thursday. 

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

The monsoon trough extends from 09N78W to 04N90W to 04N96W. The 
ITCZ continues to 10N123W, where it is bisected by a trough that 
is along a position from 16N119W to 10N124W. The ITCZ resumes at 
10N125W to beyond 08N140W. No significant convection is noted.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

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

A modest pressure gradient in the SW U.S. is maintaining gentle 
to moderate NW winds across the Gulf of California. The gradient 
between strong high pressure building southward over the western 
U.S. and thermal troughing will support fresh to locally strong 
NW winds in the northern part of the gulf this evening through 
Wed evening. Moderate NW-N winds over offshore Pacific waters 
along with seas of 4-6 ft will change little through Thursday.

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

Gulf of Papagayo: A tight pressure gradient over Central America 
supports strong to near gale force winds this morning. Fresh to 
strong NE winds are elsewhere N of 08N between 85W-86W. Model 
guidance indicates that these winds will change little through 
Wednesday with seas in the range of 8-10 ft. These seas will 
propagate to the SW away from the fetch area, and reach to near 
08N and 98W on Thursday.

REMAINDER OF THE AREA...

A trough is across the NW corner of the area from 30N136W to 
28N140W. Long period NW swell is west of a line from 30N126W to 
12N123W to 08N140W, and scatterometer data shows fresh to strong 
NE winds from 13N to 19N between 125W and 135W. Seas are 8-12 ft 
with the highest seas N of 22N. The swell will gradually decay 
through Thursday.

$$
Mundell