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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 230230

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Sun Oct 23 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 0000 UTC surface analysis and satellite imagery through
0200 UTC.


A 1007 mb surface low remains embedded in the monsoon trough near
12N101.5W. Showers and thunderstorms in association with this
area of low pressure have not changed much in organization. Latest
satellite imagery shows a cluster of moderate to strong convection
within about 90 nm W semicircle of low. Scattered moderate
isolated strong convection is noted elsewhere from 10N to 14N
between 101W and 104W. Environmental conditions are expected to
gradually become more conducive during the next day or two, and a
tropical depression is likely to form before Tuesday while the low
moves west-northwestward at 10-15 kt. The latest Tropical Weather
Outlook gives this system a high chance of tropical cyclone
formation through 48 hours.

A gale warning remains in effect for the Gulf of Tehuantepec.
Minimal gale force winds are expected tonight into early Sun
morning, then winds will diminish to 20-30 kt during the day.
Northerly winds will continue to surge across the Tehuantepec
area, increasing again to 30-35 kt Mon night into early Tue
morning, and Tue night into early Wed morning with the assistance
of the nocturnal drainage flow. Seas are forecast to build to
10-12 ft with the strongest winds.


The monsoon trough extends from 10N86W to 12N94W to 1007 mb low
pressure near 12N101.5W to 1009 mb low pres near 14.5N115W to
11N122W to 1009 mb low pres near 11N128W to beyond 12N140W.
Cluster of moderate to strong convection from 11N to 13N between
119W and 121W. Another cluster of similar convection is from 12.5N
to 14N between 123W and 125W. Scattered moderate convection elsewhere
from 10N to 14N between 117W and 121W, and from 05N to 09N between
82W and 85W.



For the Gulf of Tehuantepec area, see special features section above.
A sub-tropical ridge axis extends from NW to SE across the offshore
waters of Baja California Sur near 21N118W. Light to gentle NW
winds are expected across the Pacific waters of baja California
through Sunday before weak troughing develop just offshore of Baja
California Sur to produce light and variable winds. Combined seas
of 4 to 6 ft in NW swell are expected through early Sun before
seas build to 5-8 ft Sun through Mon in a new pulse of NW swell.

Inside the Gulf of California, mainly gentle southerly winds are
noted based on scatterometer and surface data. This general wind
direction will persist on Sun, then light and variable winds are
expected on Mon.

Light and variable winds are also expected elsewhere within 250
nm of the Mexican coast W of the Gulf of Tehuantepec through Sun,
except moderate E to SE winds are expected across the outer waters
between Acapulco and Cabo Corrientes due to the current low pres
SW of Tehuantepec moving across the area. Please, special features
section for more details about this tropical low.


Gulf of Papagayo: fresh to locally strong NE winds are expected
across and just downstream of the Gulf of Papagayo early Sun
morning and Monday morning. Gentle to moderate S to SW winds are
noted per scatterometer data S of 05N, while gentle to moderate W
to NW winds are N of 05N. Combined seas of 4 to 6 ft, primarily in
long- period SW swell dominate the offshore waters. These marine
conditions will persist over the few days.


A ridge dominates most of the north waters N of 20N W of 118W.
Under the influence of this system, mainly gentle to moderate
winds are noted per scatterometer data. Winds increase to 15-20
kt near the monsoon trough due to the presence of three low pres
systems, previously mentioned.

A new pulse of long period NW swell is spreading SE across the NW
waters. This swell event is expected to reach the waters W of
Baja on Sun. Then, seas will subside below 8 ft by Sun night. 

A cold front will be near 30N140W Sun night and will move across
the NW waters on Monday, stretching from 30N133W by Monday
evening. This front will be reinforcing by a second cold front
reaching the same area on Tue. The merging cold front is forecast
to extend from 30N134W to beyond 26N140W by Tue night.