000
AXPZ20 KNHC 161949
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Thu Dec 16 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
1930 UTC.

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

The monsoon trough extends from 1008 mb low pressure near the
coast of Colombia at 09N76W to 10N85W to 07N101W. The ITCZ 
extends from 07N101W to 08N113W, then resumes west of a surface
trough from 08N118W to 10N127W, then resumes west of another
surface trough from 07N133W to 06N140W. Scattered moderate and 
isolated strong convection is noted from 06N to 13N between 113W
and 127W. Scattered moderate convection is noted from 05N to 08N
between 108W and 113W, from 06N to 10N between 128W and 133W, and
from 05N to 08N between 137W and 140W.

OFFSHORE WATERS WITHIN 250 NM OF MEXICO

Low pressure troughing stretches across northwestern mainland
Mexico while relatively well defined high pressure ridging
dominates the waters north of 15N. The pressure gradient between
the troughing and ridging is supporting moderate to fresh winds
from about Cabo Corrientes northward including offshore of Baja
California and throughout the Gulf of California. Seas are 8 to 
11 ft across these same waters, except in the Gulf of California
where they are 4 to 7 ft in the central and southern Gulf, and 2
to 4 ft in the northern Gulf. Fresh to strong N to NE winds are 
flowing through the Gulf of Tehuantepec where seas are 5 to 7 
ft. Gentle to moderate winds and 3 to 6 ft seas prevail 
elsewhere. 

For the forecast, large NW swell swell west of around 105W will 
decay by the weekend. Fresh NW to N winds west of Baja California
will increase to fresh to strong west of Baja California Norte 
tonight, with conditions improving west of Baja California by the
end of the week. Moderate to fresh winds in the Gulf of 
California will diminish tonight, then fresh to strong in the 
northern Gulf Fri afternoon through Sat. Fresh to strong N winds 
in the Gulf of Tehuantepec will pulse through Fri morning, then 
return Sun afternoon, possibly increasing to near gale or gale 
force Sun night through Tue night. 

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

Fresh to strong NE winds prevail across the Papagayo region.
Light to gentle winds are noted elsewhere north of the monsoon
trough. Gentle to moderate S to SW winds prevail south of the
monsoon trough. Seas of 3 to 6 ft in background mixed swell
dominate the offshore waters.

For the forecast, NE to E winds will pulse to fresh to strong in the
Papagayo region through the next several days. Gentle to moderate
winds will prevail elsewhere. No significant swell events are
forecast through early next week.

REMAINDER OF THE AREA...

High pressure ridging dominates the waters north of the ITCZ. Two
surface troughs are embedded in the ITCZ, the eastern one from
11N114W to 06N117W, and the western one from 12N129W to 06N132W. 
The pressure gradient between the ridging and lower pressures 
across the ITCZ region support fresh trades north of the ITCZ to 
around 25N, with gentle to moderate winds north of 24N under the 
axis of the ridge. Gentle to moderate SE to S winds prevail south
of the ITCZ and monsoon trough. Large NW to N swell of 8 to 12 
ft prevails north of about 04N and west of about 105W, with 5 to 
7 ft seas elsewhere.

For the forecast, a weak frontal boundary will drop south of 30N
late tonight into Fri with mainly moderate winds behind it, along
with some reinforcing northerly swell. Winds across the open
waters will gradually diminish during the first part of the
weekend while another approaching front weakens the high and
pressure gradient. The large NW to N swell will also gradually
decay through the weekend. That next front is forecast to slip 
southeast of 30N140W early Sun with moderate to fresh winds both 
ahead of and behind it. The front will slowly progress east- 
southeast through early next week. Another set of 8 to 12 ft NW
swell will follow the next front.

$$
Lewitsky