000
AXPZ20 KNHC 040336
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Mon Dec 4 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 0000 UTC surface analysis and satellite imagery through 
0215 UTC.

...SPECIAL FEATURES...

Afternoon scatterometer data indicated that gale force E winds 
had developed N of a statinoary front across the NW corner of 
the discussion area, that currently through 28N140W TO 27N137W 
TO 23N140W. The gale force winds are occurring W of 137W and 
extend into the adjacent waters W of the area that wrap into a 
1011 mb low pressure center near 26N142.5W. The low will shift 
slowly SSW and tonight, with the front sinking slightly S with 
it and weakening. This will act to weaken the pressure gradient 
and reduce the winds within the next 6 hours or so. Meanwhile, a 
low to mid level trough is analyzed to the SE of this area, from 
14N140W to 23N135W. Widespread convection described below is 
occurring E of this trough to 129W, and being enhanced by 
jetstream energy moving across it. This trough will drift NW 
through early week, resulting in a tight pressure gradient, 
fresh to strong E to SE to the NE of it, and persistent 
convection. 

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

A trough axis extends from northern Colombia near 09N75W to low 
pressure near 06N79W. The monsoon trough extends from the low to 
07N88.5W TO 06N105W. The ITCZ then continues on to low pressure 
near 09N116W to 07N124W to 13N140W. Scattered moderate to strong 
convection is from 09N TO 15N between 110W AND 120W, and 
from 15N TO 24N between 129W and 137W. 

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Gulf of California: Strong high pressure will build well N of 
the area, over the U.S. Great Basin and northern Rockies through
the early part of the week. This will support strong northerly
winds over the northern Gulf of California by early Mon, 
spreading into the central Gulf Mon night and early Tue, and the 
southern Gulf Tue night into Wed. Seas are expected to build up 
to 10 ft across the north part of the basin by late Tue and to 6-
9 ft across the rest of the basin Wed through Thu. Winds may 
reach to near gale force over the northern Gulf Mon night and 
Tue, at least in gusts, with strong northeasterly gap winds 
penetrating across areas in Baja California Norte into the Bay 
of San Sebastian. The winds will diminish slightly Wed, but will 
increase again late in the week as reinforcing high pressure 
builds N of the region, and produce another period of strong to 
near gale force winds.

Gulf of Tehuantepec: Higher pressure N of the area continues to 
support fresh to strong gap winds through the Gulf of 
Tehuantepec. Associated seas are 7-9 ft this evening in shorter 
period swell generated from the strong gap winds reaching 200 to 
300 nm downstream of the Gulf of Tehuantepec, mixed with longer 
period NW swell. The high pressure will weaken through tonight, 
allowing for the plume of stronger winds to shrink. Even so, 
winds will continue to pulse, mainly at night, to fresh to 
strong through Thu morning, possibly increasing to gale force by 
Thu night as a cold front pushes across the western Gulf of 
Mexico and through southern Mexico. Looking ahead, strong high 
pressure building N of the area behind a Gulf of Mexico cold 
front will supporting a persistent strong gale event across the 
Gulf of Tehuantepec through late in the week.

Elsewhere off the Pacific coast of Mexico, weak high pressure is
maintaining gentle to moderate breezes across the region. Long 
period NW swell is producing seas of 7 to 10 ft swell 
propagating across all open waters, except within 100 to 200 nm 
off the coast south of Los Cabos and SW of the central Mexican 
coast. The swell will gradually decay to less than 8 ft across 
all offshore waters by Tue.

OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND 
WITHIN 750 NM OF ECUADOR...
  
Gulf of Papagayo: Moderate to fresh winds across the Papagayo 
region this evening will increase again to strong tonight. Seas 
downstream from the Gulf will build to 6 to 8 ft during the time 
of peak winds. This up and down pulsing of winds from night to 
day is expected to continue for the next few days.

Elsewhere, light to gentle N to NE winds are expected N of the 
monsoon trough, and mainly moderate S to SW winds are expected to
the S of the monsoon trough. Seas are in the 4 to 6 ft range, 
but are expected to build to 5 to 7 ft in SW swell to the S of 
the monsoon trough tonight into Mon.

REMAINDER OF THE AREA...

A surface trough along 116W-118W is racing WNW at 15-20 kt along 
the ITCZ. Active convection in a broad zone both E and W of the 
trough is being initiated by fresh E winds accompanying it. The 
trough will continue to move WNW during the next 24 hours, with 
associated winds diminishing to 20 kt or less by early Tue. 

Otherwise, NW swell greater than 8 ft covers almost the entire 
discussion waters beyond 250 nm offshore of Central and South
America. These seas will gradually decay through the early part
of the week.

$$
Stripling