Eastern North Pacific Tropical Weather Discussion (Text)

AXPZ20 KNHC 191551

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1550 UTC Thu Jan 19 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 1200 UTC surface analysis and satellite imagery through
1500 UTC.


A trough reaches from the coast of Colombia near 05N77W to
02N82W. The intertropical convergences zone extends from 02N85W
to 05N100W to 03N110W to 07N125W to 05N140W.


...A Series of Strong Cold fronts will to affect much of the 


An upper trough that stretches from north-central Mexico 
southwestward to just south of the southern Baja California 
peninsula. A very well pronounced jet stream branch rounds the 
base of the trough, and is accompanied by strong southwest winds.
Satellite water vapor imagery shows a persistent large moisture 
plume of mid and upper level clouds continuing to advect 
northeastward towards much of central Mexico with the strong jet 
stream winds. Available jet stream energy is combining with the 
deep moisture continues to produce scattered showers and 
possible isolated thunderstorms between Manzanillo and Cabo 
Corrientes. A stronger upper trough is noted on water vapor 
quickly sweeping southeastward from central California south- 
southwest to over the far northeast waters of the discussion 
area. This trough will overtake the first trough tonight into 
early Friday, and move eastward over northern and central Mexico 
through Saturday. Precipitable water and precipitation potential 
model guidance suggest that the moisture values will decrease 
Friday through Saturday along and offshore the central Mexican 
coast, however enough shallow moisture remaining will allow for 
isolated showers and thunderstorms exist over the these waters.

The aforementioned strong upper trough supports a cold front 
reaching from southern California to 27N125W. Strong southwest
winds will precede the front over starting tonight across the 
waters off Baja California Norte and the nothern Gulf of 
California. The winds will veer northwest and diminish thruogh 
Saturday across this region. Long period northwest swell of 8 to
12 ft will follow the front starting Friday across the offshore
water off Baja California, with 8 ft swell reaching Soccorro
Island by late Saturday. 

High pressure building behind the front will support strong 
notherly flow off the southern Gulf of California and off Cabo 
Corrientes by late Sunday as the leading edge of the 8 ft 
northwest swell reaches the coast near Manzanillo. Another front
will push into to the waters off Baja California Norte by late
Sunday with another round of strong northwest winds and 12 to 15
ft northwest swell.

Farther south, a cold front moving through the western Gulf of
Mexico will prompt strong gap winds through the Gulf of
Tehuantepec by Sunday night, persisting into Monday.


Strong gap winds through the Gulf of Papagayo will become 
moderate in speed early this afternoon, then become light to 
gentle variable winds by this evening before pulsing as fresh 
northeast winds late tonight and diminishing to moderate winds 
Friday morning, and becoming light to gentle winds clocking 
around from west- northwest to Friday afternoon to northwest 
Friday night and Saturday. light to gentle easterly winds will 
prevail elsewhere through Saturday. Seas will be generally 3-5 ft
in the forecast waters.


A 1024 mb high is now centered just west of the area at 27N145W.
It extends a ridge eastward to the Baja peninsula. The gradient 
between the ridge and low pressure associated with the ITCZ is 
supporting an area of fresh to strong northeast trade winds from 
08N to 11N west of 137W, with resultant seas in the 9-10 ft 
range. Fresh trades are elsewhere from 06N to 19N west of 137W, 
and from 10N to 14N between 122W-137W. Seas within these areas 
of fresh trades are in the 8-10 ft range due to mixed NE and NW 
swell. The ridge will be nudged southward over the next couple 
of days as the aforementioned cold fronts sweep across the 
waters north of 25N. This will allow the trades to decrease in 
coverage and shift westward through Saturday.

Northwest swell with seas to 8-16 ft associated with a cold 
front moving eastward across the waters north of 25N today will 
be followed by a second front expected to sweep southeastward 
across the northern waters tonight through Friday night. Wave 
model guidance shows large northwest swell will propagate 
southeastward into the waters north of 20N behind the second 
front, with seas building quite large to 15-21 ft in the far 
northern waters east of 130W late Friday into Saturday. Yet 
another cold front will move into the far northwest waters on 
Saturday preceded and followed by strong winds. This front will 
lead another set of large northwest swell through the northwest 
waters, with latest wave model guidance indicating seas in the 
14-21 ft range.


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Page last modified: Thursday, 19-Jan-2017 15:51:15 UTC