000
AXPZ20 KNHC 171522
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Fri Dec 17 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.

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

The monsoon trough extends from 09N84W to 08N95W to 09N116W to
08N126W. The ITCZ continues from 08N126W to 09N134W to beyond 
06N140W. Scattered moderate isolated strong convection is noted 
from 07N to 09 between 135W and 140W. Scattered moderate 
convection is from 09N to 13N between 128W and 133W.

OFFSHORE WATERS WITHIN 250 NM OF MEXICO

A surface trough stretches across northwestern mainland Mexico 
while a ridge dominates the waters north of 15N. The pressure 
gradient between these two features is supporting fresh to strong
NW winds west of Baja California Norte. Moderate NW winds are 
noted west of Baja California Sur and the Gulf of California,
mainly S of 28N. Fresh to strong gap winds prevail over the Gulf
of Tehuantepec. Light to gentle winds are elsewhere over the 
open waters off Mexico. Seas are in the 8-9 ft range west of 110W
and 4-7 ft elsewhere over the open waters off Mexico. Seas of 
4-5 ft are over the southern Gulf of California and 1-3 ft over 
the northern Gulf of California. 

For the forecast, NW swell west of around 110W will decay by the 
weekend. Fresh to strong winds west of Baja California will 
diminish late today. Fresh to strong winds will develop in the 
northern Gulf of California tonight through Sat. Fresh to strong 
N winds in the Gulf of Tehuantepec will diminish today, then 
return Sun afternoon, possibly increasing to gale-force 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 5 ft in 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, particularly
during the overnight and early morning hours. Gentle to moderate
winds will prevail elsewhere. No significant swell events are 
forecast through early next week.

REMAINDER OF THE AREA...

A ridge dominates the waters north of the ITCZ. Two surface 
troughs are embedded within the Monsoon trough/ITCZ, the eastern
one from 12N116W to 07N119W, and the western one from 14N134W to
06N137W. The pressure gradient between the ridge and lower pressure
in the vicinity of the ITCZ and within the troughs is supporting
moderate to fresh trades north of the ITCZ to near 23N and west 
of 120W. Gentle to moderate winds prevail elsewhere. NW to N 
swell is dominating the waters west of 110W, producing seas of 
8-11 ft. Seas of 5-7 ft are noted elsewhere. A cold front has 
moved into the northern waters extending from 30N120W to 28N125W
to 30N132W. This front has ushered in a set of reinforcing NW 
swell.

For the forecast, winds across the open waters will gradually 
diminish during the first part of the weekend while another 
approaching front helps weaken the pressure gradient. The large 
NW to N swell will gradually decay through the weekend. The next
front is forecast to move southeast of 30N140W early Sun with 
fresh to locally strong winds on either side of the front. The 
front will slowly progress east-southeast through early next 
week. The front will usher in another set of NW swell, building 
seas to 8-12 ft.

$$
GR