Tropical Weather Discussion
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488
AXPZ20 KNHC 260952
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
635 UTC Tue Sep 26 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 0600 UTC surface analysis and satellite imagery through
0830 UTC.

...SPECIAL FEATURES...

The remnants of Tropical Depression Pilar in the form of a small
cluster of weak convection are located about halfway between
Mazatlan and Culiacan Mexico near 24N107W. A residual trough of
low pressure lingering in the wake of Pilar extends from near
Cabo San Lucas in Baja California Sur to near Mazatlan Sinaloa.
Surface observations and initial model wind fields both suggest
winds in this area are 15 knots or less. Seas in the 4 to 6 ft
range near the mouth of the gulf of California should subside to
between 2 and 4 ft by Wednesday afternoon. Low level moisture
still pooling along the western slopes of the Sierra Madre
Occidental and the coastal zones from Guadalajara to central
Sinaloa through tonight will produce scattered showers and
thunderstorms, some yielding very heavy rain.

..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

The monsoon trough axis extends from 11N72W to 09N80W to 17N93W
to 13N103W to low pressure near 13.5N124.5W 1008 MB to 10N133W to
beyond 11N140W. Scattered moderate and isolated strong
convection is present in an area bounded by 09N83W to 05N89W to
10N107W to 16N94W to 09N83W and within 90 NM either side of the
trough axis between 119W and 128W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

As described above, winds and seas associated with the remnants
of Pilar have subsided to 15 kt or less and 6 ft or less,
respectively over the southern Gulf of California. Winds and seas
will continue to diminish through tonight. Light to gentle winds
are then expected to prevail over the southern Gulf of
California through Fri. Winds will be gentle to moderate over the
northern Gulf of California during the same time frame.

A weakening high pressure ridge reaches SE into the waters west
of Baja California to near 20N118W. The weakened pressure
gradient on the east side of the ridge will maintain light to
moderate NW winds along the Pacific coast of Baja through Thu
night. The ridge will remain weaken as low pressure passes well
to the north. Fresh SW to W monsoonal winds well offshore of the
Gulf of Tehuantepec will generate SW swell and wind waves which
will maintain seas of 5 to 7 ft in this area.

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

An active monsoon trough along and inland of the coasts of
Central America from Guatemala to Panama will remain the focus
for active convection over the coastal waters the next few days.
Expect moderate SW to W winds to prevail south of the trough,
with gentle to moderate variable winds north of the trough
through Friday night. Winds will freshen in this region over the
weekend in response to a developing area of low pressure over
Central America. Active convection will prevail across the
regional waters for the next few days.

Long period SE to S swell will maintain 5 to 6 ft seas west of
Ecuador and south of the Equator during the next few days.

REMAINDER OF THE AREA...

NW to N swell generated by strong winds north of the area are
producing 6 to 7 ft seas N of 20N and W of 120W. Pulses of
reinforcing N swell will maintain seas in the region between 6
and 8 feet through Wed night, then seas will subside.

Fresh to strong winds occurring around low pressure embedded in
the monsoon trough near 13N124.5W are supporting an associated
area of 8 to 11 ft seas in mixed swell. Mixed swell are
maintaining seas of 8 to 9 ft from 10N to 16N between 120W and
128W. Monsoonal SW winds will remain fresh to strong across this
general area through Wed, then subside.

Otherwise, weakened high pressure centered well N of the area
and low pressure associated with the monsoon trough will maintain
light to moderate trade winds W of 120W through Fri night.

$$
CAM



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