000
AXPZ20 KNHC 182121
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Sat Dec 18 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 1800 UTC surface analysis and satellite imagery through
2100 UTC.

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

The monsoon trough extends from southern Costa Rica near 09N83W 
to 08N95W to 1010 low pressure located near 10N109W to 09N115W. 
The ITCZ continues from 09N115W to 09N127W to 11N140W. Scattered
moderate to isolated strong convection is noted from 10N-15N
between 100W-112W, from 07N-13N between 116W-126W, and from
07N-10N between 130W-136W.

OFFSHORE WATERS WITHIN 250 NM OF MEXICO

High pressure of 1027 mb located near 33N130W extends a ridge
across the offshore waters on Baja California producing mainly 
gentle to moderate NW to N winds N of Punta Eugenia, and moderate
to locally fresh northerly winds S of Punta Eugenia. Gentle to 
moderate N winds are also noted between Las Maria Islands and 
Los Cabos, including the entrance to the Gulf of California while
light to gentle winds are observed elsewhere over the open waters
off Mexico, including the Tehuantepec region. High pressure over
the State of Nevada supports fresh to strong NW to N winds across
the north and central parts of the Gulf of California. A recent 
scatterometer pass provides observations of 25-30 kt winds over 
the northern Gulf of California but mainly N of 30N and W of 
114W. Seas are in the 6-8 ft range N of Cabo San Lazaro, and 4-6 
ft elsewhere over the open waters off Mexico. Seas of 3-5 ft 
prevail in the Gulf of California, except 5-7 ft in the northern
part of the Gulf where the strongest winds can be found.

For the forecast, seas of 6-8 ft in NW swell will continue to 
dominate the offshore forecast waters of Baja California through
this evening. Fresh to strong winds in the north and central 
parts of the Gulf of California will persist through late tonight.
A new gap wind event is forecast in the Tehuantepec area beginning
on Sun night, with gale conditions possible on Tue and Tue night,
then fresh to strong northerly winds are expected to persist in 
the Gulf of Tehuantepec through Thu night. Seas are forecast to 
build to 10-12 ft with the strongest winds. 

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

Fresh NE winds are currently 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, NE to E winds will pulse to fresh to strong in
the Papagayo region through the next several days and into next 
week, particularly during the overnight and early morning hours
each day. Gentle to moderate winds will prevail elsewhere. No 
significant swell events are forecast during the next several
days.

REMAINDER OF THE AREA...

Surface high pressure of 1027 mb centered near 33N130W dominates
the waters north of the ITCZ. The pressure gradient between the 
high pressure and lower pressure in the vicinity of the ITCZ is 
supporting an area of fresh to locally strong trade winds from 
12N to 18N W of 125W. Satellite derived wind data confirmed the 
presence of these winds. Gentle to moderate winds prevail 
elsewhere N of the ITCZ and W of 110W. Winds increase to 20-25 kt
near a surface trough that extends from 14N106W to a 1010 mb low
pres located within the monsoon trough near 10N109W. NW to N 
swell continues to propagate mainly across the waters west of 
110W, producing seas of 8-11 ft. Seas of 6-8 ft are noted 
elsewhere roughly S of 17N between 100W-110W. 

For the forecast, the swell event affecting mainly the waters W 
of 110W will gradually decay on Sun. The next cold front will
enter the NW corner of the forecast area on Sun, with fresh to 
strong winds on either side of the front. The front will reach
from 31N133W to 25N140W by early Mon morning. Another set of long
period NW swell will follow the front, building seas to 8-12 ft.

$$
GR