Tropical Weather Discussion
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000
AXPZ20 KNHC 172139
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2145 UTC Fri Nov 17 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 1800 UTC surface analysis and satellite imagery through
2130 UTC.

INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

The monsoon trough extends from 09N84W to 10N90W to 08N110W TO
10N125W where it transitions to the intertropical convergence
zone, and extends from 10N125W to beyond 10N140W. Scattered
moderate convection is noted from 07N to 10N between 117W and
120W. Similar convection is from 11N to 14N between 123W and
131W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

The weak 1018 mb surface high centered earlier near 25N124W has
dissipated. This system will be reinforced by a stronger high
pressure from the N on Sat. Under this weather pattern, expect
gentle to moderate northerly winds across the offshore waters W
of Baja California today, with moderate to fresh NW to N flow,
and building seas of 6-7 ft N of 25N Sat morning through late
Sun.

Gulf of Tehuantepec: Pulses of strong northerly drainage flow,
with seas building to a max of 10 ft, are forecast late tonight
into early Sat morning, diminishing afterward as the high
pressure over the eastern slopes of the Sierra Madre mountains
weakens. Another strong cold front will enter the Gulf of Mexico
late Sat, followed by strong high pressure building into
northeast and central Mexico through Sun. This will support a
return of strong gap winds in the Gulf of Tehuantepec by early
Sun, reaching gale force Sun afternoon through Mon morning. A
gale warning is now in effect for the area in the latest High
Seas forecast. NWP guidance indicates winds of 35-40 kt and
building seas of 14-15 ft by Sun night.

Gulf of California: Strong high pressure building north of the
area over the Great Basin will support fresh to strong NW winds
across the northern Gulf of California by mid-day Sat, spreading
into the central and southern portions of the gulf late Sat into
Sun, before diminishing late Sun. Seas are forecast to build to 6
or 7 ft across the central gulf early on Sun.

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

Gulf of Papagayo:  Moderate to locally fresh NE drainage winds
are forecast during the overnight hours through the middle of
next week with seas building to 5 ft downstream near 10N87W.

Light and variable winds, and 3 to 5 ft seas, are expected
elsewhere to the N of 09N, while moderate to locally fresh
southerly winds, and 4 to 7 ft seas, are forecast S of 09N
through the middle of next week.

REMAINDER OF THE AREA...

A complex 1017 mb occluded surface low is centered near 29N132W
with another center near 28N128W. The associated cold front
enters the forecast waters near 30N128W and extends to 20N137W.
ASCAT-A and ASCAT-B passes from 1800-1900 UTC today indicated
NE winds of 20 to locally 25 KT N of the area with lighter winds
in the discussion area. A pair of altimeter passes showed 8 to
10 ft seas in the wake of the front. The complex lows are
forecast to drift in place and weaken significantly. The front
will become stationary later today and gradually dissipate
tonight into Sat.

Strong SE to S return flow will develop across the NW waters N
of 27N W of 138W by Sat night, in advance of the next cold front
forecast to approach the far NW corner of the area Sun night.
The front will move slowly with the strong S to SW flow persisting
over the NW waters on Mon. At that time, expect fresh to strong
winds and seas of 8 to 10 ft covering roughly the waters N of 24N
W of 136W.

Farther S and N of the ITCZ/Monsoon trough, expect gentle to
moderate trade winds and 4 to 6 ft seas through Sat, with moderate
to fresh trades and seas of 6 to 7 ft by Sat evening into Sun.

$$
Cobb



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