Eastern North Pacific Tropical Weather Discussion (Text)

AXPZ20 KNHC 191041 CCA

Tropical Weather Discussion...corrected
NWS National Hurricane Center Miami FL
1005 UTC Thu Jan 19 2017

corrected satellite imagery time

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
0945 UTC.


A discontinuous ITCZ axis extends from 04N85W to weak low pres
near 04N97W 1012 mb to 03N104W to 05N112W to 08N120W. It resumes
at 08N127W to 06N136W to beyond 06N140W. Scattered moderate 
isolated strong convection is seen within 60 nm south of the 
axis between 126W-128W. Scattered moderate convection is within 
60 nm of the axis between 129W-131W.


...A Series of Strong Cold fronts wil 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 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 Ascat pass from Wednesday afternoon highlighted gentle to 
moderate northwest to north winds west of Baja California and in 
the Gulf of California. Light to gentle northerly winds prevail 
south and east of Acapulco. Seas in the area are 5-6 ft west of 
Baja California, 1-3 ft in the Gulf of California, and 3-5 ft 

The aforementioned strong upper trough supports a cold front 
that is fast approaching the far northwest portion of these 
waters. A pre-frontal trough is ahead of this front. Rain and 
scattered showers are noted just offshore far northern Baja 
California moving eastward.

Global models suggest that the cold front will move into the 
waters off Baja California Norte today, then become diffuse ahead
of a much stronger cold front that will quickly move across the 
waters west of Baja California and the Gulf of California Friday 
through Saturday evening. This front will be accompanied by fresh
to strong winds and large northwest swell. This swell event is 
expected to build seas to 12-19 ft off Baja California Norte 
Saturday, with seas in the range of 8-13 ft are expected off Baja
California Sur. Wave model guidance indicates max seas may be 
around 21 ft in the waters north of 29N on Saturday. These marine
conditions are likely to bring hazardous marine conditions to 
mariners navigating the near shore and offshore waters, and very 
dangerous surf conditions along the coast. Southwest winds ahead 
of the second cold front are expected to increase to near gale 
force over much of the northern Gulf of California late Friday 
night, with seas building to 8-9 ft.


The strong northeast winds through the Gulf of Papagayo will 
diminish later this morning. Winds through the gulf 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 26N142W.
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.

NW 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 NW 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 10:41:45 UTC