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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 180900
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0900 UTC Sun Nov 18 2018

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. 

.INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

The monsoon trough extends from northern Colombia near 09N76W to
across Panama and to the Pacific coast of Costa Rica near 09N84W
to 06N94W. The intertropical convergence zone axis extends from
06N94W to 06N98W to 09N118W. Three areas of low pressure are W of
the ITCZ. The first low is near 09.5N120W, the second low is near
10N129W, and the third low is near 09N140W. Scattered moderate 
and isolated strong convection is from 05N to 08N between 77W and
82W, from 06N to 12N between 112W and 118W, from 05N to 10N 
between 118W and 130W, and also from 06N to 11N between 130W and 
139W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

Gulf of Tehuantepec: Strong to near gale force northerly winds 
will pulse across the gulf waters and as far S as 14.5N95W 
through late Tue. Model guidance suggests stronger drainage flow
on Tue night, and even hints at minimal gale force conditions 
developing, then back to fresh to strong Wed through Thu night.

Gulf of California: Light and variable winds are expected 
through this evening. Moderate NW winds are forecast across the 
entire gulf waters by tonight into Mon morning, then the 
pressure gradient will relax with light NW flow through Wed 
morning, then back to moderate NW flow thereafter.

A weak NW to SE ridge extends across the Mexican offshore waters 
W of 100W, with gentle to moderate anticyclonic flow forecast 
around the meandering ridge through Wed morning. A decaying cold
front will approach Wed afternoon, with stronger ridging building
in the wake of the front through the end of the week, ushering 
in moderate to fresh NW-N flow and building NW swell.

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

Gulf of Papagayo: Fresh to locally strong NE winds, with seas 
building briefly to 8 ft downstream, are expected through the
next several days.

Light to locally moderate northerly flow is forecast elsewhere N 
of the monsoon trough, while moderate southwesterly monsoonal 
flow, with 4 to 6 ft seas, is forecast S of the monsoon trough 
through the next several days.

REMAINDER OF THE AREA...  

A cold front extends from 30N136W to 25N140W accompanied by a 
fresh SW-W-NW wind shift, and 8 to 10 ft seas W of the front in 
long-period NW swell. The front will weaken as it approaches the
Baja Peninsula on Wed night, with several reinforcing boundaries
rotating through the northern waters around a parent low pres
area N of the discussion waters. The associated initial NW swell
will subside to less than 8 ft on Mon night, with additional NW 
arriving Tue night. This set will be larger with seas up to 12 
to 13 ft along 30N Wed and Wed night.

A 1011 mb surface low is analyzed at 09.5N120W surrounded by an
area of long period northeasterly swell that is mixing with 
cross-equatorial swell across the waters generally S of 17N
between 101W and 131W. This swell will gradually subside to less
than 8 ft by the middle of the week as the surface low 
progresses westward. Model guidance suggests that an elongated
trough will extend N-NE from this low through the next several
days. This trough combined with building high pres across the
northern waters will tighten the pres gradient and increase
trades to fresh to strong NW of the trough axis late Tue night
through the end of the week.

$$
Lewitsky