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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 200227

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0225 UTC Sun Oct 20 2019

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 0000 UTC surface analysis and satellite imagery through
0200 UTC.


The axis of a tropical wave is near 89W south of 16N, moving 
west around 10 kt. Scattered moderate convection is noted from 
06N to 08N between 86W and 89W. 


The monsoon trough extends from 09N76W to 15N90W to 17.5N104W to
11N123W, then resumes from 11N129W to 10N140W. Scattered moderate
isolated strong convection is occurring within 90 nm W semicircle
of 1006 mb low pressure near 17.5N104W, and within 180 nm NE 
quadrant of 1009 mb low pressure near 10N137W. Scattered moderate
convection is noted elsewhere from 05N to 10N between 80W and 
85W, from 11N to 15N between 104W and 109W, and within 120 nm of
the monsoon trough west of 134W. 


Large NW to N swell is producing 8-12 ft seas across the Baja 
California offshore waters, with 12-14 ft seas likely west of
Guadalupe Island. Fresh to strong NW to N winds will maintain an
area of 12+ ft seas over the Baja California Norte waters west 
of 118W through Sun. A weakening offshore pressure gradient will 
allow wind speeds to diminish west of Baja early next week, and 
decaying swell will allow seas to subside below 8 ft by Tue.

Weak low pressure near 17.5N104W is producing a large area of 
disorganized showers and thunderstorms. Some development of this
system is possible before it moves inland over west-central 
Mexico by late Sun. Heavy rainfall associated with this 
disturbance could produce flash flooding and mudslides across 
portions of Michoacan, Colima, and Jalisco, especially in areas 
of mountainous terrain, during the next few days. This system has
a low chance of tropical cyclone formation.

Elsewhere, fresh monsoonal flow well south of Guerrero is 
producing an area of 8-10 ft seas over the outer offshore 
waters. These conditions will diminish Sun night into Mon. 
Moderate to fresh NW winds will develop over the northern and 
central Gulf of California late Sun night and continue through 
Tue night. Strong northerly gap winds are expected across the 
Gulf of Tehuantepec late Tue night through Wed, with seas 
building to 8 ft. Looking ahead, strong high pressure expected to
build over the western United States Thu could support strong to
near gale force northerly winds over the northern Gulf of
California Thu night.


Moderate SW to W winds will prevail across much of the region 
through the middle of next week. Freshening SW flow between
Colombia and the Galapagos Islands, combined with SW swell, will
build seas to 8 ft south of Panama tonight into Sun. Wave heights
will subside early next week as offshore wind speeds diminish 
and swell decays over the region. Looking ahead, another set of 
long period SW swell will move northward into the area by the
middle of next week.


The remnant low of Octave is still centered near 11.6N125.8W 
this evening. No convection is associated with post-tropical 
Octave based on the latest satellite imagery and available 
lightning data. A slow and erratic motion is expected during the
next few days as the low maintains 20-25 kt winds, primarily in 
the NW quadrant.

Another low pressure is centered near 10N137W along the monsoon 
trough. Earlier scatterometer data showed fresh to locally strong
winds in the northern semicircle of the low, with peak seas 
likely around 10 ft. Any development of this system should be 
slow while the it drifts westward during the next few days. This 
system is expected to move into the central Pacific basin by late
Sun. This system has a low chance of tropical cyclone formation.

A large set of NW swell continues spreading across the northern 
waters, with seas 8 ft or greater found north of a line from the
Revillagigedo Islands to 10N140W. Earlier altimeter data revealed
12 ft seas extended at least as far southward as 26N124W. This 
swell will continue propagating southeastward well beyond the 
Revillagigedo Islands through Sun night. The swell will gradually
decay early next week, and seas will subside below 8 ft across 
most of the region by Tue.

Elsewhere, a high pressure ridge extends across the waters north
of 20N. Moderate to fresh NE winds were noted in scatterometer
data from this afternoon over the waters north of 18N and west of
125W. Little change is expected over the next couple days.