AXPZ20 KNHC 201556

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1247 UTC Thu Oct 20 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
1500 UTC.

Showers and thunderstorms have increased near a small area of low
pressure located near 13N114W. The most recent scatterometer pass
showed winds of 20-25 kt in association with this system and a
well defined cyclonic circulation at the surface. A cluster of
moderate to isolated strong convection is within about 75 nm E
semicircle of low center. Although upper-level winds are only
marginally conducive, this system has the potential to become a
tropical depression over the next couple of days before upper-
level winds become unfavorable for development. The low is
expected to drift northward over the next several days. Latest
tropical weather outlook gives this system a medium change of
tropical cyclone formation.

A gale warning remains in effect for the Gulf of Tehuantepec.
This gap wind event will be associated with a cold front moving S
through the western Gulf of Mexico tonight through Friday night.
N winds of 25-30 kt will begin to surge into the Tehuantepec area
this morning. Winds are forecast to continue increasing to
minimal gale force by Friday morning with seas building to 8-12 ft
by Friday afternoon. Model guidance suggests this event will be
long lived with winds to gale force lasting until early Sun, and
strong to near gale force winds persisting through the end of
next week. Expect the strongest winds during the overnight and
early morning hours, particularly between 0600-1200 UTC, with the
assistance of the nocturnal drainage flow.


The monsoon trough extends from 13N106W to 1006 mb low pressure near
13N114W to 11N123W to 13N135W to 13N140W. Scattered moderate isolated
strong convection is noted from 10N to 13N between 107W and 112W.
Similar convection is from 10N to 13N between 114W and 121W.



A ridge dominates the waters W of the Baja California peninsula.
Under the influence of this system...gentle to moderate NW to N
winds are noted per scatterometer data. The combination of these
winds and long period NW swell support seas of 7 to 9 ft W of
Baja California Norte, and 6 to 8 ft seas W of Baja California
Sur. The ridge will weaken through Friday as a cold front
approaches the forecast region. The front is expected to stall
and weaken near 30N140W by late Friday. Then, the ridge now in
place will be reinforcing by high pres in the wake of the front. A
new batch of swell of 8 to 9 ft generated N of the front is
forecast to arrive offshore Baja California Norte late Saturday
into Sunday.

Winds across the northern part of the Gulf of California north of
30N are 20-25 kt with seas of 4-6 ft. NW winds of 15-20 kt with
seas of 4-5 ft are across the central waters, mainly N of 26N.
Winds are forecast to briefly increase to 20-25 kt across the
central waters this evening. By early Friday morning, expect
mainly gentle to moderate winds and seas generally under 5 ft
across the entire Gulf of California or Sea of Cortez.

Farther south, a gap wind event with minimal gale force winds, is
expected to begin across the Gulf of Tehuantepec late tonight into
Friday morning. See Special Features section for details.


Light to gentle winds are noted per an earlier Ascat pass across
the waters between Ecuador and the Galapagos Islands with seas of
5-7 ft in SW swell, except in the lee of the Galapagos Islands.
Farther N, mainly gentle to moderate southwesterly flow prevail
with an area of moderate to fresh SW winds roughly from 06N-10N
between 90W and 103W. Seas in this area are in the 8-9 ft range
in SW swell. These marine conditions are forecast to prevail
over the next few days. Disorganized cloudiness and showers near
the coast of Central America are associated with a surface
trough. Environmental conditions are forecast to become more
favorable for some development of this disturbance over the
weekend while the system moves toward the west-northwest at
about 10 kt.


The pres gradient between the ridge to the N and lower pres near
the monsoon through is generating an area of fresh to locally strong
trade winds from 14N to 21N W of 125W with seas of 8-11 ft in
mixed NE and NW swell. Winds and seas will continue to diminish
across the west-central waters during the next couple of days.

Currently, seas of 8-9 ft, primarily in NW swell, dominate the
forecast waters N of 25N between 118W and 130W. Seas will
gradually subside to less than 8 ft in about 24 hours, but
another set of long period NW swell will reach the NW waters by
late Friday. This swell event will propagate SE covering the
waters NW of a line from 30N125W to 23N140W by early Saturday