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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 221548

Tropical Weather Discussion 
NWS National Hurricane Center Miami FL
1605 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 1200 UTC surface analysis and satellite imagery through
1545 UTC.


Gulf of Tehuantepec gale warning: minimal gale force winds
and seas  to 15 ft will continue till late morning, then diminish
to near gale force through this evening, then increase again to
minimal gale force of 30 to 35 kt winds late tonight and persist
through sunrise on Sun. A post-frontal ridge across the Gulf of
Mexico will prevail for the next few days maintaining pulses to
near gale force through Tue afternoon, with minimal gale
conditions developing on Tue evening.

A 1007 mb surface low is embedded in the monsoon trough near
11N99W. Although associated winds are currently only 15 to 20
kt, and area of sw swell resulting in combined seas of 7 to 8 ft
is observed from 09N to 11N between 96W and 103W. Scattered
moderate isolated strong convection is observed within 150 nm
either side of a line from 11N98W to 16N103W. Environmental
conditions are conducive for tropical cyclone development over
the next few days and the low reaches near 12.5N106W on Sun and
near 14.5N109W on Mon with winds increasing mainly e of


The monsoon trough forms near 13N95W and extends w through a
1007 mb low pressure at 11N99W to 11N104W, then turns nw to
15N110W, then sw through a 1008 mb low pressure at 13.5N115.5W
to a 1009 mb low pressure at 10.5N129.5W, then turns nw to
beyond TO 14N130W. 

Scattered moderate isolated strong convection is observed within
90 nm either side of a line from 14.5N112W to 10N120W in
association with the low pressure at 13.5N115.5W. Scattered
moderate isolated strong convection is observed within 90 nm
either side of a line from 10N121W to 10N135W in association
with the embedded low at 10.5N129.5W. Scattered moderate
isolated strong convection is noted elsewhere within 60 nm
either side of a line from 08N100W to 13N108W.

Scattered moderate and isolated strong convection is observed 
along the Pacific coast of Central America within 120 nm either
side of a line from 04N79W to 07N83W, within 30 nm of 09N84W and
within 90 nm of 12N90W.



See special features for the Gulf of Tehuantepec area. A weak
sub-tropical ridge axis extends from nw to se across the
offshore zones w of central Mexico. Light to gentle nw flow with
combined seas of 5 to 7 ft is expected through this afternoon.
The ridge will break down on Sun as a weak trough swings e
across the waters n of 29N tonight into Sun. Additionally. a
weak trough will extend n along 114W from a tropical low
pressure s of the area. Seas are forecast to then build to 7 to
9 ft across the waters n of 30N w of 117W tonight, and continue
through early Sun before subsiding.

Light southerly winds across the Gulf of California this morning
will increase to moderate s winds across the gulf waters n of
19.5N this afternoon, and persist through Sun night with a brief
period of fresh winds this evening. 

Light and variable winds expected through the middle of the week
elsewhere n of the Gulf of Tehuantepec area except moderate to
occasionally fresh e to se winds are forecast beyond 200 nm. 


Gulf of Papagayo: moderate to fresh ne winds are expected across
and just downstream of the Gulf of Papagayo beginning tonight
and continuing through Mon morning, except increasing briefly to
strong e winds late tonight. 

Gentle w to nw winds are expected through Sun elsewhere n of the
monsoon trough which is meandering e to w along about 09N, while
moderate to occasionally fresh sw flow is expected s of the
monsoon trough. The monsoon trough should shift s and extends
from e to w along 08N on Mon, then shift n to back along 09N
during the middle of next week. Combined seas of 4 to 6 ft,
primarily in long-period sw swell is expected across the
offshore waters for the next 3 to 5 days.


A ridge extends from 32N140W to 21N115W. Nw swell resulting in
combined seas of 7 to 9 ft is currently observed w of a line
from 32N124W to 25N140W. These seas are forecast to continue to
propagate e and gradually subside to less than 8 ft through late

The ridge will shift s on Sun allowing a weak cold front to move
into the far nw waters near 30N140W followed by a stronger front
on Sun night which will be accompnaied by a fresh sw to w to nw
wind shift with seas building to 8 ft n of 31N w of front. A
much stronger cold front will reach 30N140W on Tue accompanied
by a strong sw to w to nw wind shift and seas building to 11 ft
n of 29n within 300 nm e of the front.

Moderate ne trades and 6 to 7 ft seas are expected through
tonight s of the ridge and n of the relatively lower pressure
within the monsoon trough. Winds and seas will continue to
gradually diminish across the waters s of the ridge over the
next couple of days except for the tropical low, or tropical
cyclone previously mentioned, moving w-nw across the tropics
between 100W and 120W.