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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 202152

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2115 UTC Fri Oct 20 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
2100 UTC.


The axis of a tropical wave is N of 07N along 94W moving W at
around 20 kt. Scattered moderate and isolated strong convection
is from 07N to 12N between 92W and 97W.


The monsoon trough axis extends from 10N85W to 09N94W to 08N110W
to 09N119W. The intertropical convergence zone axis extends from 
09N119W to 10N130W to 09N134W to 10N140W. Scattered moderate and
isolated strong convection is from 07N to 09N between 87W and 
91W, from 07N to 10N between 97W and 107W, from 07N to 10N 
between 112W and 115W, and also from 08N to 10N between 131W and



High pressure over the western Gulf of Mexico and eastern slopes
of the Sierra Madre Oriental has weakened during the past 24 
hours. This has loosened the pressure gradient over the Gulf of 
Tehuantepec and allowed for a decrease in northerly flow to fresh
to strong. The pressure gradient will weaken further this 
weekend with winds diminishing to 20 kt or less Saturday. Another
cold front will enter the Gulf of Mexico on Sunday evening. This
front will bring strong to near gale force winds to the Gulf of 
Tehuantepec Sun night, and gale force to even strong gale force 
winds to the Gulf of Tehuantepec Mon night through Wed night.

The pressure gradient between building high pressure northwest 
of the Baja California Peninsula and a surface trough over the 
Gulf of California will strengthen winds west of Baja California 
Norte early this weekend. Strong NW winds will extends down the 
peninsula as far S as 24N on Sat morning. Winds are expected to 
diminish to 20 kt or less by Saturday afternoon. Long period NW 
swell generated to the NW of a dissipated cold front which was
over the N central waters will invade the waters off Baja 
California Norte this evening. Seas will peak near 15 ft off the
northernmost coast of Baja California Norte Saturday before 
starting to subside. The swell will propagate SE, with seas 8 ft 
or greater enveloping all of the offshore forecast zones W of 
Baja California through the weekend before subsiding below 8 ft N
of 26N by Tuesday afternoon through the middle of next week.

High pressure building over the Great Basin region of the 
western United States will cause NW winds to strengthen over the 
Gulf of California from Saturday night through Tuesday,
diminishing thereafter as the gradient weakens. Winds will be 
strongest on Monday when seas peak around 8 ft.


Gentle to moderate winds will prevail over the forecast area N of
the monsoon trough during the next several days. Seas of 8 to 9 
ft maintained by decaying SE and S swell across the southernmost 
zones W of Ecuador will subside by early Saturday. Moderate to 
fresh SW winds will cause seas to build to around 8 ft W of 
Colombia and S of Panama between 03N and 06N between 80W and 84W 
on Saturday.


A now dissipated cold front which was over the N central waters
has introduced a fresh set of large NW swells to the area. Seas 
near 15 ft will spread west to east from 133W over the waters 
north of 28N through the rest of today. The swell will push 
southeastward across most of the region, while gradually 
subsiding, the next few days. Highest seas will drop below 12 ft 
Sunday afternoon and seas associated to this swell are expected 
to subside below 8 ft by Wednesday.