000
AXPZ20 KNHC 122205
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Mon Mar 12 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 1800 UTC surface analysis and satellite imagery through
2145 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: Strong high pressure is 
ridging southward along the Sierra Madre Oriental mountains of 
eastern Mexico and over the western Gulf of Mexico. This will
continue through tonight, then remain in place through Wed 
night. A tight pressure gradient, typical of such synoptic 
pattern set-ups, is in place over southeastern Mexico and just 
inland the Gulf of Tehuantepec. This has lead to northerly
winds becoming strong to near gale through the Isthmus of 
Tehuantepec, and out across the Gulf within 30 nm either side of 
a line from 16N95W to 15N95W. As a cold air mass continues to 
plunge southward from eastern Mexico towards Isthmus of 
Tehuantepec, the gradient will further intensify allowing for the
strong northerly winds to soon increase to gale force and peak 
to around 40 kt with slightly higher gusts late tonight into 
early on Tue. Gale force winds will likely diminish by midday 
Thu, with brief lulls below gale force also possible during the 
afternoon hours Tue and Wed. Seas will reach a range of 10 to 16
ft late tonight into Tue morning. This latest gap wind event 
will finally wind down by Thu evening. Please see the latest 
Pacific Ocean High Seas Forecast product under AWIPS/WMO headers 
HSFEP2/FZPN03 KNHC, for more details.

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

A surface trough axis extends from 08N83W to 05N92W to 03N104W. 
The ITCZ axis continues from 03N104W to 04N110W to 02N122W to 
04N135W to 05N140W. A second ITCZ axis is S of the Equator and 
extends from just SW of the Galapagos Islands near 02S97W to 
02S113W to 04S123W to 05N140W. Scattered moderate convection is 
within 60 NM of the trough between 89W and 91W, and within 30 nm 
of the trough between 91W and 93W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Please see the Special Features section for information on the
Gulf of Tehuantepec developing gale event.

High pressure 1021 mb is centered near 29N120W with associated 
ridging extending southeastward to the open waters W of the Baja 
California peninsula. The high pres will maintain 15 to 20 kt NW 
to N winds through Tue. It is forecast to weaken and dissipate by
Wed as a decaying cold front approaches. Long period NW swell 
generated by winds behind the front will allow for seas to build 
to the range between 6 and 8 ft W of 110W Wed through Thu, 
subsiding thereafter.

Gulf of California: The pres gradient related to the high pres 
just NW of the offshore zones will continue to induce moderate 
to fresh NW winds over the central and southern Gulf, except 
fresh to locally strong NW winds are expected over the waters S 
of 26N through the afternoon, especially near Cabo San Lucas.
The pres gradient across the region will weaken Tue night 
through Fri, which will allow winds to diminish to between gentle
and moderate. A cold front or remnant trough will approach Baja 
California Norte Fri night. Winds will become southerly in the 
northern Gulf of California and increase to fresh to near gale 
force.

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

High pressure ridging over the Caribbean from the SW Atlantic is
weakening but is still causing moderate to fresh winds to pulse 
over the Gulf of Papagayo through Tue. Winds will increase back 
to fresh to strong early Tue night and through Fri night as the 
pressure gradient re-strengthens in response to high pressure 
building southeastward over the Caribbean from the Gulf of 
Mexico.

Over the Gulf of Panama, gentle to moderate winds will prevail 
through Wed, increasing to moderate to fresh thereafter. Seas are
expected to run between 4 and 6 ft as moderate cross-equatorial 
SW swell propagates through these waters, building the seas
5 to 7 ft Thu and Fri as the winds also increase.

Elsewhere, expect gentle to moderate winds and 4 to 6 ft seas to
prevail, except seas of 8 to 11 ft in northerly swells generated
from a gale force gap wind event in the Gulf of Tehuantepec, 
which will propagate into the Guatemala offshore waters tonight 
through Tue night.

REMAINDER OF THE AREA... 

A remnant surface trough extends from 32N126W to 23N134W. Scattered
moderate convection is noted within 240 to the east and 
southeast of the trough.

A cold front extends from near 32N133W to 25N140W. Fresh to 
strong SW winds are within 120 nm to the east of the front, with
seas of 8 to 11 ft. Scattered moderate is occurring within 30 nm
of a line from 32N130W to 28N133.5W to 26N135W.

Strong west winds are behind the front, with rather large seas 
of 10 to 15 ft due to a NW swell. The cold front will gradually 
weaken as it moves across the northern waters through Tue night, 
while the NW swell builds and peaks around 16 ft along 30N 
tonight into early Tue. A weaker cold front will introduce a 
round of reinforcing NW swell Wed night and Thu, with yet another
decaying front dropping S for the end of the week with another 
set of NW to N swell.

Mixed swell are producing an area of seas measuring close to 8 
ft from about 05N to 11N between 120W and 140W. This area of 
seas will gradually propagate westward and eventually merge with 
the larger area of NW swell generated by the cold front mentioned
in the previous paragraph on Tue.

$$
Aguirre