000
AXPZ20 KNHC 231500
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Wed Dec 23 2020

Tropical Weather Discussion for the eastern Pacific Ocean from
the Equator to 32N, east of 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 Tehunatepec Storm Warning: High pressure ridging N of 
the area over the Gulf of Mexico is maintaining fresh to strong 
northerly flow across the Tehuantepec region. The ridging will 
weaken by this afternoon allowing for winds to diminish to 20 kt 
or less. A strong cold front and Arctic area of high pressure 
will swiftly move by N of the area later this week. Northerly 
winds in the Tehuantepec region will return Thu afternoon rapidly
reaching gale force, and then reaching storm force Thu night 
into early Fri. Gale conditions are then forecast to persist for 
the rest of Fri into early Sat before diminishing. Large seas of
20-24 ft are possible by early Fri while a large plume of seas 
of 8 ft or greater will extend well SW-W of the Tehuantepec 
region from this event. Marine interests transiting across or in 
the vicinity of the Gulf of Tehuantepec should be aware of this 
upcoming gap wind event, and take necessary action to avoid 
hazardous marine conditions over the affected waters. Please read
the latest NWS High Seas Forecast 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 08N78W to 06N94W. The ITCZ 
extends from 06N94W to 08N103W to 08N121W to 09N138W. Scattered 
moderate and isolated strong convection is noted from 04N to 07N
E of 80W, from 08N to 10N between 111W and 120W, and from 06N to
13N between 122W and 134W.

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

See Special Features for details about an upcoming Gulf of 
Tehuantepec storm force wind event.

Gulf of California: Winds will strengthen tonight through Thu 
night as a high pressure area builds over the Great Basin area 
of United States. These winds are forecast to spread southward 
beyond the entrance of the Gulf and through Baja California Sur 
passages by Thu evening, when seas are forecast to briefly reach 
8 ft. Winds will diminish by the end of the week into the 
weekend.

Mainly gentle to moderate NW-N winds will prevail across the 
offshore waters of Baja California through Fri. Winds will
increase to moderate to fresh mainly N of Cabo San Lazaro toward
the upcoming weekend as the pressure gradient tightens between a
ridge to the W and a trough over the Gulf of California. Large 
NW swell will propagate into the waters W of Baja California Sat
night through Sun night with seas building to 8-12 ft.

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

Fresh to strong NE-E winds will pulse across the Papagayo region
the next several days as high pressure remains in place over the
W Caribbean. Swell generated during a strong upcoming Gulf of
Tehuantepec gap wind event is expected to affect the offshore 
waters of Guatemala and El Salvador late Thu night through Sat. 
Seas will build up to 14-18 ft, especially Thu night and Fri. 
Otherwise, gentle to moderate winds will prevail on either side 
of the monsoon trough, except occasionally fresh near the Gulf of
Panama.

REMAINDER OF THE AREA...

High pressure located N of the area dominates the forecast 
waters N of the ITCZ. The pressure gradient between this area of
high pressure and lower pressure in the vicinity of the ITCZ is 
supporting fresh to locally strong winds N of the ITCZ between
125W and 135W, with moderate to fresh trades elsewhere N of the 
ITCZ to 20N. Seas are 7-10 ft across the trade wind belt, highest
near the strongest winds. The trough will move westward over the
next 48 hours eventually shifting W of 140W. 

A cold front is forecast to enter the NW corner of the forecast 
region by Thu night. Fresh to strong SW winds are expected ahead 
of the front Thu night. Fresh to strong northerly winds and very
rough seas will follow the front. By Fri night, the front is
forecast to extend from 30N126W to 24N140W, then will gradually
weaken and dissipate through the weekend. A reinforcing front may
clip the northern waters by the end of the weekend. Seas are
forecast to peak around 15-16 ft behind the first front along 30N
by Fri night into early Sat.

$$
AL