000
AXPZ20 KNHC 190319
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Mon Dec 19 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 0000 UTC surface analysis and satellite imagery through
0300 UTC.

...SPECIAL FEATURES...

Gulf of California...Fresh to strong breeze northwest winds
continue to move down the length of the Gulf of California and
have likely reached 26N this evening.  Strong high pressure will
move equatorward over the U.S. Great Basin and increase the
north-south pressure gradient over the Gulf of California.
The winds will thus increase substantially over the northern
Gulf and will be at or near gale force early Monday morning,
with seas building to 11 ft north of Tiburon Island. The 18Z
GFS, the 12Z ECWMF, and the 12Z UKMET models all concur on peak
winds for the event of 30-35 kt.  Winds and seas will then
diminish through early Tuesday as the high weakens and shifts
east, leaving areas of 20 to 25 kt winds across the Gulf.  Winds
should diminish below 25 kt by late Wednesday.

Gulf of Tehuantepec...A strong cold front reached the Bay of
Campeche by 00 UTC.  Cooler, drier air behind the front are
moving across the isthmus of Tehuantepec into the Gulf of
Tehuantepec currently, with winds reaching gale force around
0600 UTC on Monday. A large plume of gale force winds, possibly
reaching near storm force by Tuesday, will persist into early
Wednesday across the Gulf of Tehuantepec. While the GFS and
UKMET deterministic models are extremely aggressive for the peak
of this event - nearly 50 kt, the ECMWF barely shows gale force.
Will go with 45 kt peak at this point, the event may peak at
minimal storm force.  Seas likely to reach as high as 18 ft by
Tuesday morning given the strength and extent of the gales.
Winds very gradually diminish below gale force with subsiding
seas by Thursday as the air mass to the north modifies and
shifts east.  After a brief hiatus on Thursday, the next cold
front moving across the Gulf of Mexico is likely to reinforce
the Tehuantepec event on Friday and Saturday.  Another gale
force event is a distinct possibility, though the model guidance
is mixed for this as well.
  
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...  

The monsoon trough extends from 08N78W to 07N96W. The ITCZ
continues from 07N97W to 09N118W.  The ITCZ resumes from 09N123W
to beyond 08N140W. Scattered moderate and isolated strong
convection is located within 60 nm of the ITCZ between 123W and
130W.

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Gale warnings are in effect for the Gulf of Tehuantepec and
northern Gulf of California. See Special Features section above
for details.

Moderate to fresh northerly flow persists over the waters off
Baja California today, with 5 to 7 ft seas. The winds will
diminish Monday across the region. A small plume of fresh to
strong gap winds will emerge off Baja California Sur near Todos
Santos Tuesday with seas building to 7 ft offshore. These winds
will diminish by late Wednesday.

Elsewhere offshore of Mexico, and outside of the Gulf of
Tehuantepec and Gulf of California, gentle to moderate breezes and
3 to 5 ft seas will persist.
     
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...

Fresh to strong northeast winds are expected to pulse across the
Gulf of Papagayo and coast of Nicaragua during the overnight and
early morning hours through Wednesday morning, with the
assistance of the nocturnal drainage flow. Seas should build to
building to 10 ft west of 90W. NE swell will merge with the Gulf
of Tehuantepec gap wind event to provide a large fetch of 8-12
ft seas between 10-13N to 110W on late Tuesday and to 117W on
late Wednesday.  The Gulf of Papagayo winds should diminish by
late Wednesday and remain weak the rest of the week.  Winds will
generally be northerly fresh breeze or weaker across the Gulf of
Panama through the end of the week.

REMAINDER OF THE AREA...

A 1033 mb high pressure is centered north of the area at 37N134W
west of California.  This is supporting a broad area of fresh to
strong northeast to east winds over much of the region north of
07N and west of 120W late today. Farther east, an upper level
trough to the west of Baja California will become cut off near
24N124W by early on Tuesday. The upper level trough has been
inducing a surface trough that currently reaches from 08N121W to
13N119W. The trough will become more amplified and low pressure
could consolidate within it as it drifts northwest into the
ridge through the next couple of days. The tighter pressure
gradient on the N side of this system will enhance the area of
northeast winds Monday through mid week. Seas will build to
about 12 ft from 13N to 25N west of 125W by this afternoon as
longer period NW swell mix with shorter period NE swell.
  
$$
CWL