000
AXPZ20 KNHC 211546
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 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 1200 UTC surface analysis and satellite imagery through
1500 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: High pressure building behind a
cold front moving across the Gulf of Mexico. This high pressure
is centered on eastern slopes of the Sierra Madre Mountains in 
Mexico, and this is supporting gap winds to minimal gale force 
over the Gulf of Tehuantepec 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 10N85W to 07N95W to 09N110W to
09N115W. The ITCZ continues from 09N115W to 09N125W. Scattered
moderate convection is evident from 07N to 09N between 88W and
91W. 

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.

1019 mb high pressure is centered west of Punta Eugenia near
27N117W. Moderate to fresh NW to N winds persist through most of
the Gulf of California, primarily over the central Gulf, with 
light to gentle breezes off the Pacific coast of Baja California.
Farther south, 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 by late Fri. NW
swell up to 7 ft will follow the front, impacting mainly the
waters off Baja California Fri and Sat.

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 gap winds will continue to pulse in the 
Papagayo region into mid week, then increase to 20-25 kt as high 
pressure builds north of region through Fri. Gentle to moderate 
breezes will persist elsewhere. No significant swell events are 
forecast during the next several days. 

REMAINDER OF THE AREA...

Scattered showers and a few thunderstorms are noted within 60 nm
east of a 1011 mb low pressure centered near 19N129W. Earlier
scatterometer satellite data showed fresh to strong winds within
90 nm of the center of this low, and seas are estimated to be
reaching 8 ft in this area. The low pressure is centered ahead 
of a cold front extending from 30N130W to 23N140W. Long period NW
swell follows the front with wave heights reaching 8 to 10 ft.
Elsewhere, gentle to moderate winds persist, with 5 to 7 ft seas
west of 120W primarily in NW swell, and 4 to 6 ft seas east of
120W.

For the forecast, the low pressure will dissipate today ahead of
the approaching cold front. The cold front will move eastward 
across the waters north of 20N 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 this 
afternoon, and N of 15N W of 125W by Wed afternoon. 

$$
Christensen