000
AXPZ20 KNHC 292158
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1950 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 1800 UTC surface analysis and satellite imagery through
2100 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning...The pressure gradient between
high pressure over eastern Mexico and lower pressure within the
monsoon trough over the eastern north Pacific is supporting strong
to near gale force winds over the Gulf of Tehuantepec. Gale force
winds will begin tonight and continue 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 over 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 and 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 09N79W to 10N84W to 05N91W to
05N95W. The ITCZ continues from 05N95W to 07N109W to 09N130W.
Scattered moderate and isolated strong convection is present from
03N to 06N between 77W and 81W.

...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 between the southern tip of Baja California
and Cabo Corrientes. The trough will weaken Friday night and
Saturday. This will relax the pressure gradient and allow wind
speeds to decrease to 20 kt or less on Friday morning. A surface
trough will arrive from the SW over the waters adjacent to the
coast of Baja California Norte this weekend. This will strengthen
winds slightly and cause seas to build to between 8 and 9 ft
within this area on Friday. The trough will shift east of the area
Saturday and allow seas to subside below 8 ft. The next cold front
will usher in a set of northwesterly swell Saturday night and
Sunday. Seas will build to near 10 ft in zone PMZ011 off the coast
of Baja California Sunday. The swell will begin to subside on
Sunday afternoon and allow seas to fall below 8 ft by Monday
afternoon.
  
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, then subside. 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 22N129W TO 29N129W, while
weakening high pressure is noted north of the area near 41N128W.
The pressure gradient between these features has loosened enough
to allow winds to decrease below 20 kt. Lingering NW swell are
propagating through the northern waters. Seas associated with
these swell will subside below 8 ft Friday. Trades north of the
ITCZ have also diminished to 20 kt or less. Lingering mixed NW and
NE swell prevail from 07N to 18N W of 130W with seas in the 8-9
ft range. Seas over this area will also subside below 8 ft Friday.
Trades north of the ITCZ are expected to remain below 20