000
AXPZ20 KNHC 210844
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Tue Dec 21 2021

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
0950 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: A building ridge across the 
eastern slopes of the Sierra Madre Mountains in Mexico supports a
gap wind event across the Tehuantepec region. Winds will further
increase to minimal gale force through tonight. Seas will build 
to 8 to 11 ft with the strongest winds. Fresh to strong northerly
winds will continue to blow across the Gulf of Tehuantepec through
early Fri morning. Seas 8 ft or greater generated by this gap 
wind event will reach as far west as 12N97W. Please read the 
latest NWS High seas Forecast issued by the National Hurricane 
Center at website:
https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details.

Of note, the 20-year Climatology of the Tehuantepec gap wind 
events indicates that on average 16 gale-force events and 5 
storm-force events occur in the Gulf of Tehuantepec per cold 
season. Most gale-force events occurred during November and 
December, while most storm-force winds occurred in January.

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

The monsoon trough extends from near central Costa Rica near 
09N83W to 08N104W. The ITCZ continues from 08N104W to 08N117W to
09N127W. Scattered moderate convection is seen 205 nm south of
the monsoon trough E of 84W. Scattered showers are noted
elsewhere along the boundaries. 

OFFSHORE WATERS WITHIN 250 NM OF MEXICO

A Gale Warning remains in effect for the Gulf of Tehuantepec. 
Please, see the Special Features section for details.

High pressure located over the Great Basin of US extends a ridge
across Baja California and the offshore forecast waters. Under 
the influence of this system, mainly light to gentle winds are 
noted W of the Baja California Peninsula per scatterometer data.
Outside of the Tehuantepec area, light to gentle winds are 
observed elsewhere over the open waters off Mexico with seas of 
3-5 ft. Seas of 1-3 ft prevail in the Gulf of California.

For the forecast, a ridge will continue to dominate the offshore
forecast waters of Baja California through Thu. A cold front 
will approach to the northern Baja California toward the end of 
the work-week. No significant swell event is expected to propagate
across the offshore waters of Baja California over the next 
several days.

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

Moderate to locally fresh NE winds are observed in the Gulf of 
Papagayo. Light to gentle winds are noted elsewhere north of the 
monsoon trough while gentle to moderate S to SW winds are seen
south of the monsoon trough per scatterometer data. Seas are 
generally 3 to 5 ft across the offshore forecast waters. 

For the forecast, fresh to locally strong NE to E winds will 
continue to pulse in the Papagayo region through the early 
morning hours on Tue, then mainly moderate to fresh NE to E winds
will prevail. By Wed night, winds are forecast to increase again
to 20-25 kt in the Papagayo area as high pressure builds N of 
region. This will likely persist through Fri. No significant 
swell events are forecast during the next several days.

REMAINDER OF THE AREA...

A cold front is moving across the NW corner of the forecast area
and extends from 29N131W to 23N139W. E of the front, a ridge 
dominates mainly the waters N of 15N and E of 128W. Fresh to 
strong winds are on either side of the front while light to 
gentle anticlyclonic flow is noted under the influence of the 
ridge. A new set of long period NW follows the front, with seas 
in the 8-12 ft range. A surface trough extends from 19N132.5W 
to a 1011 mb low near 17N133W to 13N140W. Moderate to locally 
fresh winds are noted per scatterometer data near the northern 
end of the trough, with seas of 7-8 ft.

For the forecast, the cold front will move eastward across the 
northern forecast waters over the next couple of days before 
dissipating. The swell event that follows the front will continue
to propagate across the forecast area, with seas of 8-10 ft covering
most of the region the N of 20N W of 125W by Tue afternoon, and 
N of 15N W of 125W by Wed afternoon. The surface trough will remain
nearly stationary through at least Tue before it merges and
dissipates. 

$$
Torres