000
AXPZ20 KNHC 141554
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1333 UTC Fri Dec 14 2018

Tropical Weather Discussion for the eastern Pacific Ocean from
the Equator to 32N, east of 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
1445 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: Gale force winds will follow 
in the wake of a cold front crossing the Bay of Campeche this 
morning. The front will move quickly over the Isthmus of 
Tehuantepec and initiate strong gap winds over the Gulf of 
Tehuantepec by early afternoon, followed by gale to strong gale 
force winds by late afternoon. Computer model guidance suggests 
that these gales will continue through the weekend and will last 
until Mon afternoon. Peak winds are forecast to be around 40 kt 
on Sat as corresponding seas quickly build to near 18 ft. 

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

The monsoon trough extends from 07N75W to 07N90W to 06N103W. The
intertropical convergence zone continues from 06N103W to 09N128W
to 08N133W, then resumes from 08N138W to beyond 08N140W. 
Scattered moderate and scattered strong convection is flaring 
from 03N to 07N east of 81W. Scattered moderate convection is 
evident from 07N to 10N between 125W and 132W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

Weak high pressure ridging E from 25N140W to near 28N116W is 
maintaining light to gentle breezes across the Pacific waters off
Baja California. Fresh to strong NW flow continues over the Gulf
of California along the E shore of the Baja Peninsula between 
24N and 27N. The winds by the pressure gradient between troughing
just inland from the eastern shore of the Gulf of California and
a wedge of high pressure reaching from the Great Basin to north 
central Mexico. Meanwhile a shot of long period NW swell is 
entering the area from the west, currently just reaching Punta
Falsa along the central Baja coast. NW swell will dominate the 
offshore waters off the entire Baja California coast through the 
Revillagigedo Islands with seas up to 9 ft by tonight, followed 
by reinforcing NW swell through Sun. 

Looking ahead, a cold front will reach the northern coast of 
Baja California by Mon night, accompanied by more substantive 
reinforcing NW swell, bringing seas of 12 to 18 ft to all of the 
offshore zones of Baja California and into the Revillagigedo 
Islands as well by late Tue. Swell of this size and period will 
present hazardous seas for mariners, as well as cause very 
powerful and dangerous surf along the Pacific reefs and beaches.

A mid to upper-level disturbance is approaching the area from 
the west. This disturbance is currently interacting with a
surface trough extending from 07N137W to 13N136W to 18N129W. The
disturbance may bring a few showers to the central and southern 
portions of the Baja California Peninsula and Gulf of California
tonight through Sun.

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

Gulf of Papagayo...Fresh gap winds will pulse to around 20 kt 
tonight before ramping back up to between fresh and strong 
during the overnight and early morning hours Sat night. These 
conditions will then persist through Mon night as high pressure 
builds north of the region. Seas are expected to max out near 10 
ft Sun morning.

Gulf of Panama...Fresh northerly winds across and downstream of 
the Gulf will slowly diminish through Sat, then become fresh 
from the north Sat night through Tue.

Elsewhere, gentle to moderate winds will persist on either side 
of the monsoon trough through early next week, as seas remain in 
the 4 to 6 ft range.

REMAINDER OF THE AREA... 

Recent altimeter passes indicated seas near Clipperton Island
have subsided below 8 ft.

Farther west, a persistent surface trough extends from 07N137W 
to 13N136W to 18N129W. A scatterometer pass from 0644 UTC showed 
fresh to strong winds on the W side of the trough between 16N and
19N. Satellite-derived sea height data from 0740Z indicate 
corresponding seas in this area as high as 12 ft. The high 
pressure ridge to the NW will weaken today and tonight ahead of 
an approaching cold front, allowing the winds to diminish to 
between moderate and fresh by tomorrow morning.

The cold front crossing the NW corner of the discussion area 
from 30N135W to 28N140W is introducing a new round of NW swell 
with seas of 9 to 16 ft following the front. The front will slow 
then dissipate trough Sat, with the swell propagating ahead of 
the front and subsiding as well. Elsewhere NW swell in excess of 
8 ft will more or less dominate the waters west of 110W through 
Sun. A stronger cold front will usher in very large NW swell, in 
excess of 20 ft, which will enter NW portions of the forecast 
area early Sun. Seas of 12 ft or higher could encompass almost 
all of the forecast waters N of 07N and W of 115W by Tue morning.

$$
CAM