000
AXPZ20 KNHC 080836
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
836 UTC Sat Oct 8 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 0600 UTC surface analysis and satellite imagery through
0830 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning...high pressure building
southward over eastern Mexico and the Gulf of Mexico will tighten
the pressure gradient across the isthmus of Tehuantepec over the
next several days. This will allow fresh gap winds which combined
with overnight drainage effects will result in strong to near-
gale force winds this morning. The gradient will tighten even
more through late today with minimal gale force winds expected
Saturday night into Sunday. A cold front will move across the Gulf
of Mexico late this weekend which will allow dense, cooler, and
drier air to push into the Gulf of Tehuantepec, increasing the
winds to 30 to 40 kt Sunday night. Gap winds will diminish
slightly thereafter as the airmass to the north modifies and
shifts east.

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

The monsoon trough axis extends from 09N84W to 1011 mb low
pressure near 11N117W to 11N140W. Scattered moderate convection is
observed within 120 nm south of the monsoon trough axis between
85W and 115W, and within 60 nm north of the axis between 115W and
130W.

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A sub-tropical ridge axis extends from northwest to southeast across
the Pacific waters to the Revillagigedo Islands. Strong northerly
winds off the coast of California to the north of the region had
supported a surge of northerly swell 6 to 7 ft across the waters
offshore of Baja California. The swell is expected to subside to 4
to 6 ft through the next 24 hours. Light to gentle northerly
breezes will persist across the region north of the Gulf of
Tehuantepec and including the Gulf of California through the next
several days on the western periphery of the weak ridge.

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

Light to gentle westerly winds are expected through tonight north
of the monsoon trough which is meandering east to west along
about 11N, while moderate southwest flow is expected south of the
monsoon trough through the upcoming weekend. Winds will become
light and variable across the waters north of 11N today, with
little change except moderate easterly flow possible across the
Gulf of Papagayo on Sunday night. Combined seas of 3 to 6 ft,
primarily in long-period southwest swell, is expected across the
offshore waters later in the period from the early to middle part
of next week. Fresh trade wind flow is likely between 10N and 15N
between the low pressure areas, and the mostly stationary ridge to
the north early next week.

REMAINDER OF THE AREA... 

High pressure 1020 mb was centered north of the area near 35N132W
will shift southeastward through the next couple of days, ahead of
a cold front moving into the forecast area in the next 36 to 48
hours. Areas of moderate to fresh trade winds persist north of the
monsoon trough to near 20N, with seas of 5 to 7 ft. Global models
are in good agreement showing a series of weak low pressure areas
forming along the monsoon trough. Although the model depictions
differ somewhat in precise locations, there is some general
agreement of low pressure forming between 115W and 120W through
late Sunday and there is a moderate chance of tropical cyclone
development with this low early next week as it tracks westward
along the monsoon trough west of 125W. Expect winds of 20 to 25 kt
with seas to 9 ft within 180 nm in the southeast semicircle of the
low pressure with the next 36 to 48 hours.
      
$$
CHRISTENSEN