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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 281511

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1511 UTC Fri Oct 28 2016

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 1200 UTC surface analysis and satellite imagery through
1500 UTC.


Gulf of Tehuantepec Gale Warning...a high pres ridge across
eastern Mexico combined with lower pressures to the south of the
Gulf of Tehuantepec near the monsoon trough, continues to produce
a tight pressure gradient across the area. As a result, strong
northerly winds will continue to pulse to minimal gale force
through early Saturday. The gradient is forecast to weaken
slightly thereafter, allowing for winds to remain below gale
force through early next week. Seas will occasionally build to 12
to 14 ft during the strongest winds.


The monsoon trough axis extends from 10N74W to 08N103W to low
pressure near 10N1140W to 10N121W. The intertropical convergence
zone axis extends from low pressure near 12.5N134W to 10N140W.
Scattered moderate convection is within 90 nm in the northwest
semicircle of the low near 12.5N134W.



See the special features section for details on a persistent Gulf
of Tehuantepec gap event.

Gentle to moderate NW winds prevail across the waters offshore of
the Baja California peninsula. Winds will slowly diminish this
weekend, as a dying cold front moves E and the pres gradient
weakens. Combined seas of 5 to 7 ft with northwest swell will
subside to 4 to 5 ft this weekend, then will build to 6 to 9 ft by
Sunday as another cold front and a new set of north swell moves
across the northern waters. The front will gradually dissipate as
it approaches the area by early next week, with swells decaying

In the Gulf of California, light and variable winds are expected
today as an elongated northwest to southeast trough lingers across
the gulf. Low pressure is forecast to develop in the far northern
Gulf of California by early Saturday. Winds on the southeast side
of the low are forecast to pulse to moderate to fresh through early
next week. Seas will be 2 ft or less across the northern gulf
through the weekend, building to 4 to 7 ft as the winds increase,
with 2 to 4 ft seas expected over the southern half through early
next week.


Gentle to moderate west to northwest winds will prevail north of
the monsoon trough, except moderate offshore winds will occur with
nocturnal drainage flow Saturday night through early next week.
Moderate southwest winds south of the monsoon trough will increase
to moderate to fresh this weekend through early next week.
Combined seas of 4 to 6 ft, will subside to 3 to 5 ft this
weekend, building early next week to 5 to 7 ft.


Low pressure, which is the remnant circulation of tropical
cyclone Seymour, is located near 23N122.5W at 1007 mb. A small
area of scattered moderate convection is located in the northeast
quadrant between 60 nm and 240 nm. Lingering seas of 8 to 14 ft
will quickly subside to less than 8 ft by early Saturday as the
circulation continues to spin down, with a remnant trough expected
by early Sunday.

A dissipating cold front extends from 30N125W to 24N132W, with a
pre-frontal trough north of 26N within 75 nm east of the front.
Associated winds on either side of the front are 20 kt or less,
however, mixed southeast and northwest swells of 8 to 11 ft are
found across the northwest portion of the discussion waters behind
the front. The front will dissipate by early Saturday as a new
cold front quickly moves in from northwest of 30N140W. This next
front will usher in a reinforcing set of northwest swells with
seas building to up to 12 to 15 ft along 30N by early Sunday. The
front will weaken as it translates to the east-southeast. Model
guidance shows another front with an even more impressive set of
northwest swell arriving by the middle of next week.

Otherwise, trades south of 20N are mainly moderate, but will
increase locally to fresh across the west central waters Sunday
into early next week, as high pressure ridging builds in behind
the next front, while a trough of low pressure along the ITCZ
moves toward 140W.