986 
AXPZ20 KNHC 200938
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Tue Dec 20 2022

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 0600 UTC surface analysis and satellite imagery through
0930 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: High pressure will build
southward along the eastern slopes of the Sierra Madre Mountains 
today as a western Gulf of Mexico low pressure system shifts 
eastward. As this happens, the gradient in southeastern Mexico 
will tighten as cold dense air surges southward toward the Gulf 
of Tehuantepec gap region. The resultant surge of northerly 
winds out over Tehuantepec will reach gale-force in the range of 
30-35 kt on Tuesday evening, and is expected to last through 
early Wed evening. Seas are forecast to build to 8-12 ft. 
Northerly winds will then gradually diminish Wed afternoon and 
night. Seas will subside to about 8 ft by sunrise Thu. Please 
read the latest High Seas Forecast issued by the the National 
Hurricane Center at website 
https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details.

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

The monsoon trough axis extends from low pressure of 1008 mb over
northwest Colombia near 10N75W southwestward to 07N79W and 
northwestward to 10N85W, then southwestward to 06N94W, where 
latest scatterometer data indicates that it transitions to the 
ITCZ and continues to 07N116W to 08N130W and to beyond 09N140W. 
Scattered moderate convection is seen within 30 nm north of the 
ITCZ between 126W-129W.

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Please see the Special Features section for information about an
upcoming gale event in the Gulf of Tehuantepec and possible
storm force winds. Currently north winds of fresh speeds are 
in the Gulf of Tehuantepec to near 15N, where seas are peaking 
to around 6 or 7 ft.

Relatively weak high pressure is present over the area, with the 
associated gradient allowing for light to gentle N to NE winds 
across the Baja California offshore waters, gentle to moderate NW
winds across the Gulf of California extending to the waters 
offshore of CAbo Corrientes. Seas across these waters range 3-4 
ft, except for lower seas of 2-3 ft in the Gulf of California. 

For the forecast, fresh northerly winds will continue to diminish
across the Gulf of Tehuantepec through tonight, as the pressure 
gradient in eastern Mexico relaxes. Strong northerly winds will 
return to the Gulf of Tehuantepec by late Tue morning as strong 
high pressure surges southward over eastern Mexico. Gale-force 
winds are then expected as described above. Looking ahead, the 
next Tehuantepec gap wind event is expected for Fri, with gale 
force starting by around the early evening hours Fri and 
continuing through the weekend. These winds may briefly reach
storm for late Fri night.

Meanwhile, fresh to strong NW winds are developing in the
central and southern Gulf of California as strong high pressure 
builds over the western U.S. These fresh to strong winds will 
continue across all but far northern portions of the Gulf 
through Wed morning before diminishing in the afternoon. Seas 
are expected to reach to near 8 ft by late Tue morning. The high 
pressure will weaken on Wed allowing for these winds to diminish 
to fresh speeds, then gradually diminish further through the end 
of the week.

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

Fresh to strong northeast to east winds are in the Gulf of 
Papagayo region, while fresh east winds extend offshore of 
Papagayo, Nicaragua, and the Gulf of Fonseca, extending 
southwestward to 90W. Seas are 6-8 ft over these waters. Light to
gentle winds prevail elsewhere north of the monsoon trough along
about 08N, with seas of 4 ft. Light to gentle S-SW winds and 
seas of 4-5 ft due to long-period S to SW swell are present south
of the monsoon trough. 

For the forecast, fresh to strong northeast to east winds will 
continue in the Papagayo region through the rest of the week due 
to the pressure gradient related to high pressure ridging NE of 
the region. The strongest winds are mainly expected at night and
into the mornings, when seas are expected to build near 8 ft. 
Moderate northerly winds are expected tonight through Tue in the
Gulf of Panama before diminishing slightly through the end of
the week. Gentle winds will continue across the Central American
offshore waters through most of the week along with moderate 
seas.

REMAINDER OF THE AREA... 

The area W of 120W is under the influence of high pressure that
is centered on a 1026 mb high north of the area near 34N124W. 
The southern tail of a cold front has moved into the NW waters, 
and it is weakening from 30N135W to 26N136W. Latest scatterometer
data shows mostly fresh southeast to south winds N of 27N and 
east of the front to near 133W. Seas are 6-8 ft in W-NW swell 
across this area. Elsewhere, light to moderate NE-E winds are 
present N of 20N and W of 120W. Seas over this area are 5-6 ft. 
Moderate to locally fresh winds are noted from the ITCZ to 20N 
and W of 115W, with gentle to moderate southeasterly winds south 
of the ITCZ. Seas are in the range 5-7 ft, except for slightly 
higher seas of 6-9 ft in the far western part of the area from 
05N to 15N W of 131W due to long-period NW swell. Elsewhere, 
moderate or weaker winds with slight to moderate seas are 
prevalent. 

For the forecast, moderate to locally fresh trade winds S of 20N
and W of 120W are expected to change little through Thu. NW 
swell in the far western part of the area will migrate SE to 
near 120W by Wed night. A cold front associated to a large low 
pressure system will approach the NW waters on Wed night into 
Thu. A strong pressure gradient to the E of the front will 
produce strong to near gale-force southerly winds across the far 
NW waters beginning Tue night, and shift eastward to N of 22N and
W of 137W on Wed afternoon before lifting northward out of the 
area through Thu morning. Gale-force winds are expected just to 
the W and NW of 30N140W during this time, with a low probability 
of these gales moving into the local NW waters, however, there 
may be brief instances of occasional gusts to gale- force. Large
swell producing seas 14-17 ft are expected to propagate through 
this area Tue night through Wed night, then begin to slowly 
subside on Thu.

$$
Aguirre