973
AXPZ20 KNHC 090255
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Tue Dec 9 2025

Tropical Weather Discussion for the eastern Pacific Ocean from
03.4S to 30N, east of 120W including the Gulf of California, and
from the Equator to 30N, between 120W and 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.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: High pressure is building over
the eastern slopes of Mexico in the wake of a cold front moving
across the Gulf of America. The pressure gradient between this
area of high pressure and lower pressure within the eastern north
Pacific monsoon trough is ushering in gale force gap winds in
the Gulf of Tehuantepec. High pressure will further build over
eastern Mexico tonight, further tightening the pressure gradient
and increasing winds to around 40 kt. Gale-force winds will then
likely persist through Tue evening. Very rough seas, peaking
around 12 or 13 ft, are expected with this event tonight into
early Tue morning. Of note: The monthly distribution of
Tehuantepec events shows that the largest number of gale force
events occurs in December. Storm-force events occur most often in
January. Please read the latest High Seas issued by the
National Hurricane Center at website:
https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

The monsoon trough extends from along Panama and Costa Rica to
the Gulf of Papagayo near 11N86W to 07N99W to 1011 mb low
pressure near 11N119.5W to 11.5N121.5W. The ITCZ continues from
11.5N121.5W to beyond 07.5N140W. Scattered moderate and isolated
strong convection is noted from 09N to 17N between 107W and 126W,
and from 06.5N to 09N between 132W and 136W.

...OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A Gale Warning is in effect for the Gulf of Tehunatepec. Please
see the Special Features section for more information.

Aside from conditions in the Gulf of Tehuantepec, a ridge
extends from a 1032 mb high centered near 35N131W across the
offshore forecast waters of Baja California. The pressure
gradient between this ridge and a trough over western Mexico is
supporting fresh to locally strong winds over the Gulf of
California, and gentle to moderate winds over the waters west of
the Baja California peninsula, except locally fresh near the
Revillagigedo Islands. Light to gentle winds and moderate seas
in long period NW swell are noted across the remainder of the
Mexican offshore waters.

For the forecast, gale-force northerly gap winds in the Gulf of
Tehuantepec will peak around 40 kt tonight, with gale-force winds
continuing through Tue evening. Occasionally fresh to locally
strong NW to N winds and moderate seas are expected in the
central Gulf of California through Tue morning. Fresh N winds may
develop near Cabo Corrientes Tue night through Wed night.

...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA,
AND WITHIN 750 NM OF ECUADOR...

Light to gentle winds prevail N of 05N, with gentle to locally
moderate southerly winds S of 05N. Seas are mainly moderate in
mixed SW and NW swell, with exception of slight seas nearshore
from Colombia northward.

For the forecast, mainly gentle winds will prevail N of the
monsoon trough over the next several days, except pulsing to
moderate to fresh in the Gulf of Papagayo beginning early Tue,
locally strong at times. Gentle to moderate winds will prevail S
of monsoon trough. Moderate N winds will pulse in the Gulf of
Panama starting Tue night. Seas generated by a gap wind event in
the Gulf of Tehuantepec are expected to spread across the outer
offshore waters of El Salvador and Guatemala Tue and Tue night.
Otherwise, moderate seas in mixed SW and NW swell are expected
over the regional waters through the week and into next weekend.

...REMAINDER OF THE AREA...

High pressure dominates the waters N of 20N, anchored by a 1032
mb high centered near 35N131W. A surface trough is analyzed from
19N108W to 11.5N113W. Meanwhile a 1011 mb low pressure area is
embedded in the monsoon trough near 11N119.5W. The pressure
gradient between this area of high pressure and the trough and
low pressure is supporting moderate to fresh winds N of the ITCZ.
Seas are in the 5-9 ft range over these waters, highest S of 21N
and W of 130W. Moderate winds, and seas of 4 to 7 ft, prevail
elsewhere over the discussion waters, locally fresh S of the
monsoon trough.

For the forecast, little change to the synoptic pattern and
marine conditions are expected through the middle of the week,
with winds weakening somewhat later in the week as the pressure
gradient weakens. Meanwhile, a new set of long period NW swell
is forecast to reach the NW part of the forecast region by Wed
evening, building seas to 8 to 9 ft over these waters before
subsiding by the end of the week.

$$
Lewitsky