000
AXPZ20 KNHC 291523
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1438 UTC Thu Dec 29 2016

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
1500 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning...The pressure gradient between
high pressure over eastern Mexico and lower pressures within the
monsoon trough over the eastern north Pacific is supporting gale
force winds in the Gulf of Tehuantepec. A slight increase in the
gale force winds will occur tonight into Friday as high pressure
builds behind a cold front moving across the Gulf of Mexico. The
area of high pressure will then shift rapidly into the
southwestern Atlantic waters Saturday morning, which will cause
the winds over the Gulf of Mexico to veer. This will decrease winds
funneling into the Gulf of Tehuantepec which will bring an end to
the latest gale force gap wind event. Please see the latest
National Hurricane Center High Seas Forecast product under
AWIPS/WMO headers MIAHSFEP2/FZPN03 KNHC for further details.

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

The monsoon trough extends from 08N83W to 05N90W to 05N93W. The
ITCZ extends from 05N93W to 06N110W to 10N121W to 10N140W.
Scattered moderate convection was noted within 60 nm north of the
ITCZ between 96W and 100W. 

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Please see the special features for details on the Gulf of
Tehuantepec gale-force gap wind event. The pressure gradient
between a high pressure ridge west of the Baja California
peninsula and a surface trough over western Mexico is supporting
fresh to strong winds over the southern Gulf of California. The
trough will weaken Friday night into Saturday. This will help
loosen the pressure gradient, with resulting winds decreasing to
20 kt or less late Friday night. A surface trough will shift into
the coastal waters off the coast of Baja California Norte this
weekend. This will strengthen winds over this area Saturday into
Sunday. the trough will shift east of the area Sunday and winds
will decrease to 20 kt or less late Sunday. This trough will usher
in a set of northwesterly swell Saturday with seas building to
near 10 ft off the coast of Baja California Saturday. The swell
will subside through the weekend, falling below 8 ft by Monday. 
  
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...

Fresh to strong winds will pulse at night over the Gulf of
Papagayo through Saturday. Peak winds will occur during the
overnight hours as the gap winds are enhanced by nocturnally
induced drainage flow. Winds will decrease to 20 kt during the
late afternoon and early evening hours. Elsewhere, winds will
remain 20 kt or less, with seas below 8 ft through the end of
the week.

REMAINDER OF THE AREA...

A weakening surface trough extends from 29N128W TO 22N128W, while
weakening high pressure is noted north of the area near 40N127W. The
pressure gradient between these features has loosened enough where
winds have diminished to 20 kt or less. Lingering northwesterly
swell is propagating through the northern waters. Seas associated
to this swell will subside below 8 ft Friday. Trades north of the
ITCZ have also diminished to 20 kt or less. Lingering mixed
northwest and northeast swell prevails over these waters with
seas in the 8-9 ft range. Seas over this area will also subside
below 8 ft Friday. Another set of northwesterly swell will move
into the northwest waters late tonight. Seas associated to this
swell will peak near 10 ft late tonight, and will subside below 8
ft this weekend.

$$ 
AL