000
AXPZ20 KNHC 161006
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Sat Dec 16 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
0945 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: Strong to near gale force 
north to northeast winds are presently in the Gulf of Tehuantepec
region and well to the southwest of the Gulf to near 11N98W. 
Seas are 8-10 ft within these winds. The gradient associated to 
developing low pressure area over the Gulf of Mexico will bring 
fresh to strong northerly winds over the western part of the 
Gulf. These winds will support the return of gale-force winds in
the Gulf of Tehuantepec by this afternoon. Northerly winds are 
forecast to increase to 30-35 kt with seas building to the range 
of 9-13 ft tonight into Sun morning. This gap wind event will 
continue well into next week, with winds briefly diminishing 
below gale-force by Sun night into Mon, then increasing again to
gale-force Mon night through Wed night. Rough to very rough seas
are expected.

NW Eastern Pacific Gale Warning: A nearly stationary deep 
extratropical low pressure system is located north of the area 
near 34N138W. It is forecast to meander through Sun night. A 
tight pressure gradient associated with this low pressure 
system will remain in place over the northwest corner of the 
forecast area through early Sun. A cold front presently extends 
from near 30N129W to 20N133W and to 14N140W. Near gale southwest 
winds are ahead of the front to near 125W and north of 25N along 
with seas of 8-12 ft in a west to northwest swell. Strong west to
northwest winds are west of the front north of 24N with seas of 
13-19 ft in a west to northwest swell. Last night the ship with 
call letter ID "RCLKYXB" reported west winds of 30 kt near 
26N138W.

The extratropical low will drive a second cold front into the 
far northwest forecast waters by early this afternoon while a 
third cold front is expected to reach the same waters tonight. 
Gale-force southwest to west winds are expected north of about 
29N and west of about 136W this afternoon into tonight, 
diminishing to just below gale-force by late tonight. This next 
front will usher in an extensive set of northwest swell to the 
northwest forecast waters this afternoon and tonight. The 13-19 
ft seas will even grow larger, to the range of 16-24 ft, from 
this afternoon through tonight before they begin to slowly 
subside into early next week. Before they subside, they are 
likely to lead to hazardous marine conditions. Thee leading edge 
of the 12 ft and greater seas will reach as far south as 18N and 
west of about 127W by Sun afternoon. 

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 northern Colombia near
10N75W southwestward to 09N85W to 06N96W to 05N105W, where 
latest scatterometer data indicates that it transitions to the 
ITCZ and continues to 06N114W to 05N122W to 08N130W to 10N135W 
and to 10N140W. Scattered moderate to isolated strong convection
is within 120 nm either side the of the trough between 81W-86W. 
Scattered moderate convection is within 120 nm north of the 
trough between 99W-104W, within 60 nm south of the trough between
102W-108W, and within 30 nm south of the ITCZ between 116W-119W.

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

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

The combination of high pressure over the U.S. Great Basin and 
relatively lower pressure over northwest Mexico and the Gulf of 
California area is allowing for fresh to strong northwest to 
north winds over the entire Gulf of California with seas to 6 
ft. These winds are spilling out of the Gulf reaching as far 
south as the waters between Cabo Corriente and 109W. Meanwhile, 
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. No significant convection
is presently noted over these waters.

For the forecast, the ongoing gap wind event in the Gulf of 
Tehuantepec region. It is forecast to persist well into next 
week. Strong to near gale force northerly gap winds will continue
this morning, then increase to gale force in the afternoon. 
These winds are forecast to remain at gale force into the middle 
of next week. Rough to very rough seas can be expected with these
winds. Meanwhile, high pressure will build over the Great Basin 
in the western United States today. The associated gradient will
maintain fresh to strong northwest winds over the Gulf of 
California through early this afternoon, then diminish to 
moderate to fresh speeds through Sun and to gentle speeds Mon. 
Seas to around 8 ft associated with a large swell event will 
reach the outer offshore forecast waters of Baja California 
between Cabo San Lazaro and Punta Eugenia by Sun night. 

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

Moderate northeast to east winds are in the Gulf of Papagayo 
region, including the coast of southern Nicaragua per an
overnight ASCAT data pass. Seas with these winds are in the 
range of 3-5 ft. To the northwest of the Gulf of Papagayo 
region, seas of 5-8 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.

Scattered showers and a few thunderstorms are along and just 
inland the coast of Colombia from 01N to 05N.

For the forecast, the moderate northeast to east winds in the 
Gulf of Papagayo will increase back to fresh to strong beginning 
Sun night, and continue through the middle of next week while 
expanding to the southwest. These winds are expected to reach 
near gale force Tue night and Wed. Rough seas are expected over 
the Guatemala and El Salvador offshore waters Sun and Sun night 
due to another Gulf of Tehuantepec gap wind event that begins on 
Sat. Elsewhere, winds are moderate or weaker for the next several
days. 

...REMAINDER OF THE AREA...

A strong extratropical cyclone is affecting the NW corner of the
forecast region currently bringing strong to near gale force
winds and very large seas to that part of the discussion area. 

Elsewhere, 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, trade winds north of the ITCZ to near 13N will
increase slightly to fresh speeds through Sun. 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 late 
Sun. Swell from the Tehuantepec gap wind event will spread
southwest and west reaching to near 104W by late Sun, with 
generated seas of 8-9 ft.

$$
Aguirre