Tropical Weather Discussion
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000
AXPZ20 KNHC 191041 CCA
TWDEP

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.

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

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.

...DISCUSSION...

...A Series of Strong Cold fronts wil to affect much of the
area...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

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
elsewhere.

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.

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

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.

REMAINDER OF THE AREA...

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.

$$
AGUIRRE


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