000
AXPZ20 KNHC 140912
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0900 UTC Thu Feb 14 2019

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 0600 UTC surface analysis and satellite imagery through
0900 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: High pressure over the Gulf of
Mexico has started to shift eastward, with winds over the SW Gulf
veering in response. This has continued to slowly diminish winds
funneling through the Chivela pass into the Gulf of Tehuantepec.
The overnight ASCAT pass indicated winds just reaching gale 
force, with winds expected to diminish below gale force early 
this morning. Winds over the Tehuantepec region will continue to 
diminish to 20 kt or less this afternoon. Resultant seas have 
started to subside, and are currently peaking near 13 ft. Seas 
will continue to subside, lowering to 8 to 11 ft early today, 
and to 8 ft in mixed northeast and northwest swell by late 
tonight. Please see the latest High Seas Forecast issued by the 
National Hurricane Center under AWIPS/WMO headers Fzpn03/Hsfep2, 
or at the website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml 
for more details.

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

A surface trough extends from 07N97W to 05N90W. The ITCZ extends
from 05N90W to 02N95W to 02N116W to beyond 06.5N140W. Scattered 
moderate isolated strong convection is noted within 90 nm north 
of the ITCZ between 92W and 104W. 

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...  

Please refer to the Special Features above for details on the 
ongoing gale force gap wind event in the Gulf of Tehuantepec.

High pressure of 1017 mb is centered to the west of the Baja 
California Peninsula near 24.5N117W. A weak pressure gradient 
over the offshore waters of Baja California is generally 
producing light to gentle winds, in anticyclonic fashion, with 
seas of 4 to 6 ft in northwest swell. A weakening cold front will
move across the far northern waters west of Baja California 
Norte tonight. The front will dissipate across central Baja and 
the Gulf of California on Fri. Moderate to fresh northwest to 
north winds will follow in behind the front, while gentle to 
moderate winds ahead of the front. Seas will build to near 16 ft 
to the west of Baja California Norte this weekend as strong 
northwest swell propagates into the area and northwest winds west
of the Baja California increase to fresh to strong speeds. 

Elsewhere, light to gentle mainly northwest to north winds and 
seas in the 4 to 6 ft range will continue between the Gulf of 
Tehuantepec and Cabo Corrientes through Fri, then increase some 
on Sat mainly north of Manzanillo.

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

Moderate to fresh winds over the Gulf of Papagayo will pulse to 
strong tonight, then diminish Fri through Sun. Elsewhere winds 
fresh breeze or weaker will prevail across the forecast waters 
through Mon. 

REMAINDER OF THE AREA... 

A cold front extends from a 992 mb low centered well north of 
our area near 41N126W through 30N127W to 25N132W to 21N140W. A 
ridge of high pressure is building in the wake of the front, 
extending from a 1034 mb high centered near 41N161W. A tight 
pressure gradient prevails west of the front between the 
building ridge and low pressure. The pressure gradient is 
supporting strong to near gale force winds N of 28N west of the 
front to 138W, as depicted by the overnight ASCAT pass. Also 
depicted by the overnight ASCAT pass is a trough which has 
developed E of the front roughly from 20N131W to 13N140W. The 
scatterometer pass depicted fresh to strong winds prevailing 
within 60 NM N of the trough between 132W and 136W. The overnight
altimeter passes suggest seas slowly subsiding, currently
reaching 15 ft west of the front. 

The front will progress eastward, reaching Baja California late 
today with the winds gradually diminishing. With the wind 
forcing relaxing, the NW swell will continue to progress 
southeastward, but gradually diminish. A more vigorous NW swell 
will reach the NW corner of the discussion area Fri night, with 
a large area of 12 ft seas peaking near 16 ft on Sat. This swell 
will spread over much of our area, bringing at least 12 ft seas 
as far south as 10N through Mon.

Total precipitable water imagery shows ample deep-layer moisture 
streaming northeastward from southeast of the Hawaiian Islands 
to the California coast and extreme Baja California Norte. The 
moisture is being advected by southwesterly flow located ahead 
of a rather extensive upper-level trough axis extending from the 
NW United States southwestward to just N of Hawaii. The upper 
level trough supports the deep low pressure system. Areas of 
elevated showers and thunderstorms with patchy light showers is 
embedded within these clouds, and expected to last through the 
end of the week before it shifts entirely inland across 
California.

$$
AL