337 
AXPZ20 KNHC 170920
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Sun Dec 17 2023

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
0915 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: Gale-force north to northeast 
winds of 30-40 kt are presently occurring in the Gulf of 
Tehuantepec, with seas in the range of 9-13 ft. These conditions
will change little through Mon as high pressure ridges southward
over eastern Mexico. Seas are forecast to reach a peak of 14 ft 
on Tue.

NW Eastern Pacific Gale Warning and Significant Swell event: A 
deep extratropical low pressure system is located north of the 
area near 33N137W with pressure of 986 mb. A stationary front 
out ahead of this low pressure system stretches southward to 
30N126W to 22N129W and to 15N137W. Meanwhile, a cold front is 
just northwest of the discussion area. Gale-force southwest
winds are north of 28N and between 133W-137W. These winds will 
lift north of 30N this morning as the low tracks to the 
northeast. An extensive set of northwest swell will propagate 
through the northwest and central sections of the area through 
Tue, at which time it will have reached the southern half of the 
area west of about 110W, but will have decayed quite a bit by 
that time. Seas are currently peaking to 24 ft within the area of
gale winds. Seas of 17-23 ft in NW swell are elsewhere north of 
26N west of 134W, and 8-12 ft over remainder waters north of 10N 
and west of 122W. Seas of 8 ft or greater will extend as far 
south as 04N and west of 118W by late on Mon.

Please read the latest NWS High Seas Forecast issued by the 
National Hurricane Center at 
https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details.

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

The monsoon trough axis extends from northwest Colombia westward 
to central Costa Rica, then to 10N85W to 07N91W and to 06N99W, 
where latest scatterometer data indicates that it transitions to 
the ITCZ to low pressure near 07N103W 1009 mb and continues to 
06N113W to 06N125W to 07N131W and to 08N140W. Numerous moderate 
to isolated strong convection is within 60 nm of the ITCZ between
105W-112W. Scattered moderate convection is seen from 05N to 08N
between 83W-89W, and within 60 nm of the ITCZ between 101W-105W.

...OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Please refer to the Special Features section for details on an 
ongoing Gulf of Tehuantepec Gale Warning.

Fresh northwest winds are over central and southern sections of 
the Gulf of California. A weak pressure gradient dominates the 
Mexican offshore waters, outside of the Gulf of Tehuantepec. 
Moderate or weaker winds and slight to moderate seas continue 
across the rest of the offshore waters. Seas across the Baja 
California offshore waters and over the southern Mexico offshore 
waters are in the 4-6 ft range due to long-period west to 
northwest swell.

For the forecast, the fresh northwest winds over the central and
southern sections of the Gulf of California will diminish to 
moderate speeds this afternoon, to gentle speeds on Mon, then 
become light and variable Tue through Thu night. Seas to around 
8 ft from a large swell event will reach the outer offshore 
forecast waters of Baja California between Cabo San Lazaro and 
Punta Eugenia tonight. These seas will subside on Tue.

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

Gentle to moderate northeast to east winds are in the Gulf of 
Papagayo region, including the coast of southern Nicaragua. Seas 
with these winds are in the range of 3-5 ft. To the northwest of 
the Gulf of Papagayo region, seas of 6-9 ft in a northwest swell 
generated by the Gulf of Tehuantepec gap wind event are over the 
outer offshore waters of Guatemala and El Salvador. Gentle north 
winds and seas of 3-4 ft are in the Gulf of Panama.

Increasing scattered showers and isolated thunderstorms are over
the offshore waters of Costa Rica and Panama.

For the forecast, the gentle to moderate northeast to east winds
in the Gulf of Papagayo will increase to fresh to strong 
beginning Mon, and continue through next week while expanding to 
the southwest. These winds are expected to reach near-gale force 
Mon night through Wed. Rough seas are expected over the 
Guatemala and El Salvador offshore waters today due to the Gulf 
of Tehuantepec gap wind event. Fresh north winds are expected
over the Gulf of Panama starting tonight and continuing well  
into the upcoming week. These winds will be at fresh to strong 
speeds Tue night through Wed night. Elsewhere, winds are 
expected to be moderate or weaker for the next several days.

...REMAINDER OF THE AREA...

Refer to the section above for details on the Gale Warning and
significant swell event for the western portion of the basin.

A deep extratropical low pressure system is located N of the 
area near 33N137W with a pressure of 986 mb. A stationary front 
out ahead of this low pressure system stretches southward to 
30N126W to 22N129W and to 15N137W. Meanwhile, a cold front is 
just northwest of the discussion area. A tight pressure gradient 
associated to his system will remain in place over the northwest
corner of the forecast area today. Outside of the warning area 
described above under Special Features, a N to S high pressure 
ridge offshore southern California and northern Baja California 
controls the gradient across the remainder of the forecast waters
north of the ITCZ and west of 110W. Gentle to moderate winds are
on either side of the ITCZ/Monsoon Trough with seas of 5-7 ft in
mixed swell.

For the forecast, gale force winds over a portion of the
northwest forecast waters will lift northeast of the area 
this morning as the deep low tracks to the northeast. The trade 
winds north of the ITCZ to near 14N will increase slightly to 
fresh speeds today. Winds south of the ITCZ will be in the 
moderate to fresh range through Mon. Fresh to strong winds from 
the gap wind event of Tehuantepec will merge into the trade winds
between 100W-104W by early this evening. Swell from the 
Tehuantepec gap wind event will spread southwest and west 
reaching to near 104W tonight, with generated seas of 8-9 ft.

$$
Aguirre