000
AXPZ20 KNHC 290916
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Mon Dec 29 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
0900 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: The next gap wind event across
the Tehuantepec region will begin this afternoon as a ridge builds
across the eastern slopes of the Sierra Madre Mountains in Mexico,
behind a cold front moving across the Gulf of America. Winds are
expected to suddenly increase to 35 to 40 kt, with seas building
to 9 to 12 ft by tonight. On Tue, winds are forecast to increase
to near storm force, with seas building up to 17 or 18 ft. Fresh
to strong winds and large seas generated by this event will 
spread well away from the Tehuantepec area, with seas 8 ft or 
greater reaching as far west as 105W by Tue evening. Marine 
interests transiting across or in the Gulf of Tehuantepec later 
today through Tue night should be aware of this upcoming gap wind
event, and take the necessary action to avoid this hazardous 
marine conditions over the affected waters. Gale conditions are 
forecast to continue through Wed night. Conditions in the 
Tehuantepec region are forecast to begin to improve on Thu.

Developing Low Pressure/Swell event: A surface trough is analyzed
from 23N120W to 12N127W. This trough is paired with a vigorous 
and broad upper-level trough that is digging southward producing 
abundant cloudiness with scattered to numerous showers and 
thunderstorms, particularly from 14N to 20N between 118W and 
130W. This area is also merging with a large NW to N swell that 
has been spreading across the basin, with rough seas noted from 
05N to 27N W of 115W. Recent scatterometer satellite data
indicate that fresh to strong winds are occurring between the
trough and high pressure to the north. These winds are affecting
mainly the waters N of 20N W of 120W. Seas of 8 to 12 ft are 
within these winds. A broad low pressure area is expected to 
develop in association with this trough near 20N125W by this 
evening. The low is forecast to move northward and N of the area 
by Wed evening or Wed night. The interaction between this feature
and high pressure to the north will continue to result in a broad
zone of fresh to strong winds from 15N to 27N and west of 120W 
through tonight. Seas may reach up to 14 ft with the strongest 
winds today. Conditions are forecast to improve by the middle of 
the week.

Please read the latest High Seas Forecast issued by the National
Hurricane Center at website:
https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more information.

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

The monsoon trough extends from 10N85W to 08N95W to 09N103W. The
ITCZ continues from 09N103W to 11N123W to 07N140W. Scattered 
moderate convection is noted from 08N to 11N between 114W and 
119W. 

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

A Gale Warning is in effect for the Gulf of Tehuantepec. Please 
refer to the Special Features section for more details. 

High pressure of 1032 mb is located well north of the area near 
38N133W. A ridge axis extends from the high across the offshore 
forecast waters of Baja California supporting moderate to fresh 
north to northeast winds with moderate seas. Fresh to strong NW
winds and slight to moderate seas are found in the Gulf of 
California, while light winds and slight seas are in the Gulf of 
Tehuantepec. Elsewhere, moderate or weaker winds and slight to 
moderate seas prevail.

For the forecast, the next gap wind event in the Tehuantepec region
will begin today. See the Special Features section for more details.
Fresh to strong northwest winds and building seas will prevail 
across most of the Gulf of California through Tue night as high 
pressure persists over the SW of the United States. Elsewhere, 
moderate or weaker winds and slight to moderate seas are expected.

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

High pressure N of the area supports fresh to strong northeast to
east winds in the Gulf of Papagayo and downwind to near 87W as 
noted in a recent scatterometer pass. Seas of 4 to 5 ft are 
within these winds based on altimeter data. Weak low pressure of 
1010 mb located off Colombia is producing scattered showers and 
thunderstorms in the eastern Gulf of Panama. Elsewhere, moderate 
or weaker winds and slight to moderate seas prevail.

For the forecast, the aforementioned high pressure will continue
to support pulsing fresh to strong NE to E winds in the Gulf of 
Papagayo with moderate to rough seas through the forecast period.
Gentle to locally moderate northerly winds are expected in the 
Gulf of Panama through Fri. Seas generated by strong winds in the
Tehuantepec region will propagate across the offshore forecast 
waters of Guatemala and El Salvador Tue through Wed night. Light 
to gentle winds and slight to moderate seas are expected elsewhere
through this work-week.

...REMAINDER OF THE AREA...

Please read the Special Features section for details on a developing
low pres and a significant swell event over the central waters of
the forecast region. 

Broad surface ridge associated to a 1032 mb high pressure located
N of area near 38N133W dominates mainly the area N of 20N and W 
of 120W. The pressure gradient between the high and the above 
mentioned surface trough is allowing for a large area of fresh to
strong NE winds from 16N to 27N W of 120W. Seas of 8 to 12 ft 
are noted within these winds based on altimeter data. Elsewhere, 
moderate or weaker winds and moderate seas are prevalent.

For the forecast, outside of the developing low pressure and the
swell event, a cold front is forecast to reach the NW waters Wed
night into Thu. A reinforcing front will also reach the same area
later on Thu, merging with the main front by Thu evening. Fresh
to strong winds are expected on either side of the front. A new
swell event will follow the front bringing rough to very roughly 
seas.

$$
GR