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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 220231

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
203 UTC Sat Oct 22 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.


Numerous showers and thunderstorms located a few hundred miles
south-southwest of the Gulf of Tehuantepec are associated with a
broad area of low pressure located near 11N97.5W. Satellite
imagery indicates a cluster of moderate to strong convection
within about 150 nm NW quadrant of low. Scattered moderate is
elsewhere from 09N to 14N between 100W and 104W. Environmental 
conditions are expected to be conducive for development of this
disturbance over the next few days, and a tropical depression will
likely form early next week while the system moves toward the
west-northwest at about 10 kt.

A gale warning remains in effect for the Gulf of Tehuantepec. The
latest marine guidance suggests that the current minimal gale
force winds will increase to 30 to 40 kt tonight, then diminish
to 30 to 35 kt on Sat and continue into the early morning hours on
Sun before diminishing below gale force by late sun morning.
Minimal gale force conditions are expected to develop again late
Mon and continue through Tue night.


The monsoon trough extends from 1008 mb low pres near 11N97.5W to
12N105W to 1007 mb low pres near 13N116W to 10N124W to low pres near
11N130W to 13N140W. Scattered moderate isolated strong convection
is noted from 08N to 11.5N between 120W AND 129W.



See special features for Gulf of Tehuantepec. A sub-tropical
ridge axis extends from NW to SE across the offshore waters of
Baja California. Light to gentle NW flow with combined seas of 5
to 7 ft are expected through Sat night. Seas are forecast to then
build to 7 to 9 ft across the waters N of 27N W of 118W early Sun
morning through Sun evening.

Gentle to moderate NW winds are blowing across the Gulf of
California, and are forecast to become light and variable on Sat,
then light southerly flow is expected across the entire gulf
waters late Sat.

Light and variable winds are expected elsewhere within 250 nm of
the Mexican coast N of the Gulf of Tehuantepec through Sat, except
moderate E to SE winds are forecast beyond 200 nm on Sun and Mon
as a low pres likely develops just south of the forecast zones.


Gentle to moderate S to SW winds are noted per scatterometer data
S of 06N, while gentle to moderate W to NW winds are N of 06N. 
Combined seas of 4 to 7 ft, primarily in long-period SW swell is
expected across the offshore waters for the next 3 to 5 days.


A ridge dominates most of the north waters N of 15N W of 115W. The
pres gradient between the ridge and lower pres in the vicinity of
the monsoon trough is resulting in an area of moderate to fresh
winds between 14N and 18N W of 135W based on the latest Ascat
pass. Seas in this area are near 8 ft according to an altimeter
pass. A cold front is expected to approach 30N140W tonight while
gradually dissipating through late Saturday. A new set of long
period NW swell follows the front. This swell event will propagate
SE across the NW waters Sat and Sun, reaching the waters W of Baja
on Sun. Another cold front will be near 30N140W on Monday and will
be reinforcing by a second cold front reaching the same area on
Tue. The merging cold front is forecast to extend from 30N135W to
beyond 27N140W by late Tue.