000
AXPZ20 KNHC 150948
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Fri Dec 15 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
0930 UTC.

...SPECIAL FEATURES...

Tehuantepec Gale Warning: Gap winds in the Gulf of Tehuantepec 
region have diminished to just below gale-force per an overnight 
ASCAT pass from 0354Z that shows northerly winds of 20-30 kt. 
Seas with these winds are 8-12 ft. These winds extend downstream 
from the Gulf to near 12N97W. These seas will subside below 12 ft
this morning. Strong to near gale-force winds will continue into
the weekend, with gale force winds returning on Sat afternoon. 
This next round of gale force winds is expected to last through 
the weekend, and continue into early next week. Rough to very 
rough seas are expected. 

NW Eastern Pacific Gale Warning: Deepening low pressure of 999 
mb is northwest of the area near 33N138W. A cold front extends 
from the low to 30N138W and to 25N140W. A tight gradient between 
the front and high pressure west of northern Baja California has 
brought near gale to gale-force south to southwest winds over a 
rather broad area ahead of the front, roughly east of the front 
to 130W and from 27N to 30N. Seas with these winds are 10-13 ft. 
Another cold front will enter the forecast waters from the same 
extratropical low on Sat, bringing another round of gale-force 
winds. Expect these winds to occur north of 28N and west of 136W.
These gale force winds will diminish to just below gale- force 
on Sat night, with strong winds continuing across the northwest 
waters through Sun. Very large northwest swell propagating 
through the northwest forecast waters will produce 12 ft and 
greater seas over those waters through the weekend and into 
early on Mon. Seas of 17-24 ft are forecast for that part of the 
area from Sat through early on Sun. The leading edge of the 12 ft
and greater seas will reach as far south as 15N and west of 
about 129W by late on Sun. Seas will begin to slowly subside 
starting Sun afternoon and into early next week.

Please read the latest High Seas Forecast and the Offshore 
Waters Forecast issued by the National Hurricane Center at 
https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and 
www.nhc.noaa.gov/marine/offshores.php for details on both of
these special features.

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

The monsoon trough axis extends from northwest Colombia 
southwestward to low pressure near 05N77W 1004 mb and to 
06N87W to 06N96W to 05N103W to 04N110W, where latest 
scatterometer data indicates that it transitions to the ITCZ
to 04N110W to 07N120W to 09N127W to 10N135W and to 10N140W. 
Scattered moderate to isolated strong convection is 120 nm south
of the trough between 77W-79W, between 87W-92W, also within 60 
nm of the trough between 92W-97W and within 30 nm of the trough 
between 105W-108W.

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

Please refer to the Special Features section for details on a 
Gale Warning for the Tehuantepec region.

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 mostly fresh northwest to 
north winds over the Gulf of California with seas to 6 ft. 
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, strong to near-gale force northerly gap winds 
will continue through Sat morning, before increasing back to gale
force in the afternoon. These winds are forecast to remain at 
gale force speeds into early next week. Rough to possibly very 
rough seas can be expected with these winds. Meanwhile, high 
pressure will build over the Great Basin in the western United 
States through Sat. The associated gradient will sustain fresh to
strong NW winds over the Gulf of California through late Fri. 
These winds diminish Sat through Sun night. 

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

The combination off strong high pressure that stretches from the
eastern United States southwestward to southeastern Mexico and 
relatively lower pressure found south of Mexico is maintaining
fresh to strong trade winds in the Gulf of Papagayo region, 
including the coast of southern Nicaragua. These winds extend
westward to near 09N89W. Seas with these winds are in the range 
of 5-8 ft. In addition, seas to 9 ft in a northwest swell 
generated by the Gulf of Tehuantepec gap wind event will 
continue today over the offshore waters of Guatemala and El 
Salvador, then subside to 5-7 ft tonight.

The aforementioned strong pressure gradient is also supporting 
moderate to fresh northerly winds in the Gulf of Panama. These 
winds reach south to near 06N. Seas over these waters are 4-6 
ft. S of 06N, mostly gentle south to southwest winds are 
occurring, with seas of 4-5 ft due to mixed swell. 

For the forecast, the fresh to strong northeast to east winds
in the Gulf of Papagayo will diminish to moderate to fresh speeds
by early this evening. These winds will increase back to fresh 
to strong beginning late Sun and continue through mid week while 
expanding to the southwest. The large northwest swell over the 
Guatemala and El Salvador offshore waters will subside today. 
Expect rough seas in this area once again for 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...

Please see the Special Features section for more information on
the gale warning for the far northwest waters of the area. 

Outside the near gale to gale-force winds described above under 
Special Features, fresh to strong south to southwest winds that 
are over the northwest part of the area in advance of a strong 
frontal system are to the northwest of a line from 30N130W to 
25N135W to 23N140W. Seas with these winds are 10-12 ft. Overnight
altimeter data pass indicated seas to 11 ft near 29N134W.

A 1022 mb high center is analyzed just west of southern 
California. The associated gradient controls the wind regime over
most of the tropical eastern Pacific. Moderate to fresh trade 
winds are noted from the ITCZ north to 20N. Seas over these 
waters are 5-7 ft. Moderate to fresh southeast winds are south
of 03N and west of 125W. Seas over these waters are also 5-7 ft.
Light to gentle winds and moderate seas are present elsewhere.

For the forecast, trade winds will slowly diminish to be 
moderate or weaker today and through the weekend as the gradient 
from high pressure that is over the eastern and central sections 
of the area slackens in response to frontal systems moving into 
the northwest part of the discussion area.

$$
Aguirre