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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 040903

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Fri Dec 4 2020

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
0840 UTC.


Gulf of Tehuantepec Gale Warning: The pressure gradient between 
high pressure building behind a cold front moving across the 
Gulf of Mexico and the eastern north Pacific monsoon trough is 
generating gale force winds in the Gulf of Tehuantepec. Gale 
force winds are expected through tonight. Winds will then diminish
below gale force, with a stronger pulse of gale force winds 
expected Sun night through Tue night. Seas are forecast to build
to 15-17 ft with this stronger pulse of gap winds by Tue. Please
read the latest NWS High Seas Forecast issued by the National 
Hurricane Center at website for more details.


The monsoon trough extends from 09N83W to 07N97W to 12N115W to 
09N128W. The ITCZ continues from 09N128W to beyond 09N140W. 
Scattered moderate convection is noted from 08N to 10N between 
84W and 96W, from 08N to 11N between 105W and 110W and from 10N 
to 12N between 116W and 124W. 


Please see above for more on the Gulf of Tehuantepec gale force
gap wind event.

Elsewhere, fresh to strong winds prevail over the Gulf of 
California, with seas in the 5-7 ft range. Strong gusty NE winds 
are funneling through the passes of the Baja California 
peninsula. NW swell has propagated into the waters off Baja 
California Norte, with seas in the 8-11 ft range. The swell will 
continue to propagate southward, with 8 ft seas reaching the 
Revillagigedo Islands by late today. Seas over this area will 
subside through the weekend, falling below 8 ft on Sunday. 
Another set of NW swell will enter the waters off Baja California
early next week. Seas will peak near 15 ft off Baja California 
Norte Tue.


Fresh to locally strong NE to E winds are expected in the Gulf 
of Papagayo over the next couple of days, particularly during 
the overnight and early morning hours. Elsewhwere, light to 
gentle winds are expected north of the monsoon trough, with 
gentle to moderate S to SW winds south of the monsoon trough, 
through the upcoming weekend. Swell from the gale force gap wind
event in the Gulf of Tehuantepec will impact the waters off 
Guatemala and El Salvador today, with seas building to 6 ft. Seas
will build to 8-9 ft over these waters early next week as larger
swell is generated from the stronger pulse of gale force gap 
winds over the Gulf of Tehuantepec. Seas in the 4-5 ft range will
prevail elsewhere.


High pressure of 1030 mb is centered near 39N129W. The pressure 
gradient between this area of high pressure and lower pressure 
in the vicinity of the ITCZ, and within the monsoon trough, is 
supporting moderate to fresh trade winds roughly from 10N to 20N 
west of 120W. Seas are 8 to 12 ft in NW swell across this area. A
ridge will persist across the northern forecast waters over the 
next several days, keeping a large area of fresh trade winds. 

Large, long period, NW swell continues to propagate across most 
of the waters N of the equator and W of 120W, with seas peaking 
near 12 ft. Seas associated with this swell will slowly subside 
through the weekend. Another large NW swell event will reach the 
NW corner of the forecast area by Sat. This swell will bring seas
greater than 12 ft, and peaking near 17-18 ft, over much of the 
waters north of 20N on Tue.