000
AXPZ20 KNHC 060922
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
922 UTC Wed Dec 6 2017

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 California: Strong high pressure from the U.S. Great 
Basin and northern Rockies is supporting fresh to occasionally
strong NW winds over the northern Gulf through tonight. The
gradient will tighten further Thu as reinforcing high pressure
follows a cold front moving southward along the front range of 
the Rockies. This will allow winds to gale force over portions of
the northern and central Gulf of California Thu persisting into
Thu night as strong winds spread into the southern Gulf. Seas will
build to 10 ft over portions of the northern and central Gulf by
Thu night. Winds and seas will diminish into Sun as the high 
pressure north of the area weakens.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 
The monsoon trough axis extends from 10N85W to 08N105W, where it
transitions to the intertropical convergence zone and continues 
westward to 10N125W to 08N140W. Scattered moderate convection is 
from 06N to 10N between 113W and 117W, and from 10N to 12N 
between 123W and 125W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Gulf of Tehuantepec: Overnight drainage effects is allowing winds
to pulse to 20 to 25 kt into the morning hours. Winds will then 
persist from fresh to strong through Fri morning ahead of a cold
front moving across the western Gulf of Mexico, arriving in 
southern Mexico Thu. Winds will further increase to gale force on
Fri afternoon as the cold and dry air pushes into the Gulf of 
Tehuantepec. Seas will build to 15 ft by early Sat, with seas 8 
ft or greater reaching as far as 500 nm downstream to the W-SW of
the Gulf of Tehuantepec. Looking ahead, strong high pressure 
building behind the front across central Mexico will support a 
persistent strong gale over Tehuantepec through the weekend.

Elsewhere off the Pacific coast of Mexico, weak high pressure is
maintaining gentle to moderate breezes across the region. High 
pressure building north of area will result in strong gap winds 
pushing across low lying areas of Baja California Norte and into 
adjacent waters Thu. A larger plume of strong NE winds will push 
off the coast of Baja California Sur north of Cabo San Lazaro Thu
night and Fri, with seas 8 to 10 ft reaching from near shore to 
beyond 250 nm offshore. 

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

Gulf of Papagayo: Fresh to strong winds will pulse this morning through
the Gulf of Papagayo. Otherwise, moderate to fresh NE winds 
across the Papagayo region will persist with seas downstream 
maintaining a range of 6 to 8 ft. Winds and seas will diminish 
Thu as strong trade winds across the SW Caribbean Sea diminish 
and veer SE. Looking ahead, strong high pressure will build N of 
the region, allowing strong gap winds and building seas to 
reappear late Sat night into Sun. Winds may even approach minimal
gale force Mon.

Elsewhere, light to gentle N to NE winds are expected N of the 
monsoon trough, and mainly gentle to moderate S to SW winds are 
expected to the S of the monsoon trough. Seas are in the 5 to 7 
ft range in SW swell this evening to the S of the monsoon trough,
and will subside to 4 to 6 ft through mid week. Large NW swell 
of 8 to 10 ft from the upcoming Tehuantepec gap wind event will 
spread across the offshore waters of Guatemala late this week and
over the weekend.

REMAINDER OF THE AREA...

The trailing end of a warm front extends from 30N137W to 27N135W.
The pressure gradient between high pressure north of the front 
will continue to support fresh to strong SE to S winds north of 
the front through this morning, then diminish as the front lifts
northward. An approaching front west of the area will support 
the development of fresh to strong southerly winds north of 25N 
and west of 130W to the south of the departing warm front, with 
NW swell of 8 to 12 ft lingering N of 20N and W of 130W through 
tonight. The front west of the area will then weaken Thu and 
dissipate just NW of the discussion area early Fri as winds 
diminish over the area. Although winds will diminish, additional 
NW swell greater than 8 ft will continue to affect these waters 
through the end of the week. Looking ahead, strong southerly flow
will return late Sat north of 25N and of 135W ahead of yet 
another cold front approaching from the NW, along with a fresh 
set of large NW swell. 

Elsewhere, long period swell to 8 ft persisting across much of 
the area south of 15N will decay below 8 ft through Fri. A new 
round of NW swell to 9 ft will propagate into the discussion 
area, encompassing the region north of 15N and west of 130W by 
Thu night, then most of the area west of 120W by late Fri into 
Sat, mixing with shorter period NE waves north of 20N and east 
of 125W.

$$
Christensen