000
AXPZ20 KNHC 310937
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Sat Dec 31 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 0600 UTC surface analysis and satellite imagery through
0830 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning...The pressure gradient between
a weakening high pressure ridge over eastern Mexico and lower
pressure along the ITCZ across the eastern north Pacific is
yielding strong northerly winds to 30 kt over the Gulf of
Tehuantepec tonight, as depicted by a recent 0300 UTC ASCAT
pass. Winds have fallen below gale force and are expected to
gradually diminish through the morning hours, and then become
variable at 10 kt or less by this evening. This brings an end to
this 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... 

There is no evidence of a monsoon trough across the area waters
at this time. The ITCZ extends from 07N87W to 04N101W to 08N118W
to 06N132W to beyond 07N140W. Scattered moderate to strong
convection is noted from 01N to 07N east of 79.5W to the
Colombian coast. Isolated moderate to strong convection is noted
within 90 NM north and 60 NM south of axis between 110W and 128W.

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Please see the special features section for details on the Gulf
of Tehuantepec gap wind event. The pressure gradient between
aweak high pressure ridge west of the Baja California peninsula
and a surface trough over western Mexico has weakened in the
past 12 hours, and winds across this entire area west of
Tehuantepec have decreased to below 20 kt. Residual NW swell in
this area continue to slowly subside and area seas will fall
below 8 ft by this evening. A cold front will cross the northern
half of the Baja peninsula and far northern Gulf of California
late tonight through Sunday. High pressure behind the front will
drive fresh to strong NW winds behind the front across the
Pacific waters, while SW winds increase to 20-230 kt ahead of
the front across the far northern Gulf of California. The front
will then continue eastward into the southwestern United States
and northern Mexico Sunday night, with winds across this area
decreasing to 20 kt or less by late Sunday. The cold front will
also usher in a round of NW swell beginning on this evening. The
swell will cause seas off the coast of Baja California Norte N
of 25N to build to between 8 and 11 ft tonight, then begin to
subside on Sunday, dropping to below 8 ft by midday on Monday.
  
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...

Fresh to strong winds will linger over and downwind of the Gulf
of Papagayo through this afternoon, then decrease to 20 kt or
less this evening. Winds across the Papagayo region are expected
to increase again to around 20-25 kt each of the next few
nights, but will mainly affect the area within 120 nm of the
coast. Elsewhere, winds will remain 20 kt or less, with seas
below 8 ft through the end of the week.

REMAINDER OF THE AREA...

Northwesterly swell continue to subside over the forecast
waterswest of 120W, with seas expected to fall below 8 ft
tonight through Sunday. A weak surface ridge between 120W and
140W is producing moderate trades the north of the ITCZ to about
20N, and are expected to remain below 20 kt during the next few
days, where mixed trade-wind waves and NW swell will maintain
sea heights 6-9 ft from 09N to 20N west of 113W through Sunday
before subs