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000
AXPZ20 KNHC 190320
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 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 0000 UTC surface analysis and satellite imagery through
0300 UTC.

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

A discontinuous ITCZ axis extends from 04N89W to 03N104W to
08N123W to 06N140W. Scattered moderate convection from 08N to
10N between 125W and 134W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Satellite water vapor imagery shows a large moisture plume of
mid and upper level clouds advecting northeastward towards much
of central Mexico. Jet stream energy is combining with the deep
moisture to produce widespread offshore showers from south of
Manzanillo northward to Mazatlan. The upper trough will slide
eastward through Friday and shear out. A stronger trough will
sweep southeastward and merge into the first trough Thursday,
with associated moisture and weather shifting eastward with it.

Scatterometer data shows 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
to 3 ft in the Gulf of California, and 3-5 ft elsewhere.

Global models indicate a cold front will move into the waters
off Baja California Norte Thursday, then become diffuse ahead of
a much stronger cold front that will quickly move in across Baja
California and the Gulf of California Friday and Saturday. The
second cold 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, and 8-13 ft
seas 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 coastal
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 nigh, with seas building to 8-9 ft.

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

Northeast winds will pulse over 20 kt late tonight across the
Gulf of Papagayo and downwind to about 88W. Winds will diminish
Thursday night, becoming light to gentle variable winds Friday.

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 ridge extends eastward from 25N140W 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 13N west of 130W in 9-10 ft seas. ASCAT data
shows fresh trades elsewhere, from 07N to 20N west of 115W. Seas
with the trades are 7-10 ft in northwest swell and northeast
wind waves. The ridge will be nudged southwest over the next two
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 Friday.

Looking ahead, northwest swell with seas to 8-16 ft associated
with a cold front moving eastward across the waters north of 25N
Thursday will be followed by a second front expected to sweep
southeastward across the northern waters Thursday night and
Friday. 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.

$$
Mundell

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