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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 160358

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Sun Dec 16 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 0000 UTC surface analysis and satellite imagery through 
0330 UTC.


Gulf of Tehuantepec Gale Warning: The tight pressure gradient
over southeastern Mexico resulting from the combination of strong
high pressure over northern Mexico and lower pressure south of 
Mexico is bringing strong gale force northerly winds over the 
Gulf of Tehuantepec with seas to 18 ft. This strong gap wind 
event will continue through Sun night, before diminishing on Mon 
as the strong high pressure over Mexico shifts eastward and 
weakens. Seas with this event will subside to 9 to 13 ft Mon and 
to less than 8 ft on Tue as the northerly winds diminish to 
fresh speeds. Please refer to the latest high seas forecast 
issued under AWIPS/WMO headers HSFEP2/FZPN03 for more specific 
marine related details. 


The monsoon trough axis extends from 08N78W to 08N84W to 06N90W, 
where latest scatterometer data indicated that it transitions to 
the ITCZ and continues to 04N100W to 06N115W to 09N130W to 
08N140W. Scattered moderate convection is noted from 08N to 18N 
W of 119W.



A weak ridge will preavil over the area maintaining light to 
gentle breezes across the area. Northwest swell with seas to 9 
ft will persist in the offshore waters of Baja California 
through Sun. 

A cold front will approach the region Mon bringing a new set of 
northwest swell, with seas from 12 to 17 ft reaching the 
northern coast of Baja California Norte and Guadalupe Island. 
Swell of 12 to 15 ft will cover the Baja offshore waters to the 
Revillagigedo Islands into mid week. Swell of this size and 
period will present hazardous seas for mariners, cause very 
powerful and dangerous surf along the Pacific reefs and beaches, 
and likely produce areas of modest coastal flooding and beach 

Over the Gulf of California, strong high pressure north of region
have been supporting moderate to fresh breezes across the basin.
A mid to upper-level disturbance approaching the area from the 
west may bring a few showers to the central and southern 
portions of the Baja California Peninsula and Gulf of California 
through Sun. Strong high pressure will build N of the area by 
the middle of the week and will support fresh to strong winds 
across the northern and central gulf.


Gulf of Papagayo...Fresh to strong gap winds will pulse starting
tonight and persist into early next week as high pressure builds 
north of the area. The gap winds will diminish late Tue night. 
Seas with these winds are expected to be 8 to 9 ft. Fresh winds 
will also pulse across the Gulf of Panama and Gulf of Fonseca 
tonight and Sun. 

Elsewhere, gentle to moderate winds will persist on either side 
of the monsoon trough through early next week, as seas remain in 
the 4 to 6 ft range.


A mid to upper-level trough north of about 18N between 115W and 
134W is supporting scattered moderate convection over the 
northern waters. Seas are as high as 12 ft in this area, due to 
the local winds and a component of longer period NW swell. NW 
swell in excess of 8 ft covers most of the area north of 06N and 
west of 115W. 

A second and stronger cold front will approach the northwest 
section of the area tonight, and move eastward across the waters 
north of 20N through early next week. The main impact will be a 
new round of NW swell, with combined seas in excess of of 12 ft 
to as high as 20 ft propagating across most of the region north 
of 12N and west of 120W Sun through late Mon. 

During the early to middle part of next week, the leading edge 
of this next round of northwest swell will mix with shorter 
period northeast and east swell emerging from the gap wind areas,
and possibly even southerly swell, to create an area of mixed 
seas south of 12N between 95W and 110W.