827
AXPZ20 KNHC 090720
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 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 0600 UTC surface analysis and satellite imagery through
0700 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: High pressure continues to
build over the eastern slopes of Mexico in the wake of a cold
front exiting the Gulf of America to the SE. 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 as depicted on
recent ASCAT data with peak winds likely around 40 kt for the
next few hours. Gale-force winds will then likely persist
through much of tonight. Very rough seas, peaking around 12 or
13 ft, are expected with this event through early today. 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
09N83.5W to 08.5N95W. The ITCZ extends from 08.5N95W to 12N115W
where another monsoon trough segment continues to 10N123.5W.
Another ITCZ segment extends from there to beyond 07.5N140W.
Scattered moderate and isolated strong convection is noted from
10N to 18N between 109W and 118.5W, and from 09N to 12N between
118.5W and 125.5W.

...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 high pressure located N of the area to 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 per recent ASCAT scatterometer data,
except locally fresh near the Revillagigedo Islands due to a
surface trough located just beyond the offshore waters. 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 early today, with gale-force
winds continuing through much of tonight. Occasionally fresh to
locally strong NW to N winds and moderate seas are expected in
the central Gulf of California through this morning. Fresh N
winds may develop near Cabo Corrientes tonight through Wed
night.

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

Moderate to fresh winds are in the Gulf of Papagayo due to a
locally tight pressure gradient and nocturnal drainage, while
light to gentle winds prevail elsewhere N of 05N. 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, 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 tonight.
Seas generated by a gale-force gap wind event in the Gulf of
Tehuantepec are expected to spread across the outer offshore
waters of El Salvador and Guatemala today and tonight.
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 the ITCZ and monsoon
trough. A surface trough is analyzed from 18N110.5W to
11N114W. The pressure gradient between this area of high
pressure and the trough is supporting moderate to fresh winds N
of the ITCZ and monsoon trough as seen by recent ASCAT swaths.
Seas are in the 5-9 ft range over these waters per altimeter data,
highest S of 20N and W of 120W. Moderate winds, and seas of 4 to
7 ft, prevail elsewhere over the discussion waters.

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