809
AXPZ20 KNHC 182110
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Wed Sep 18 2024

Tropical Weather Discussion for the eastern Pacific Ocean from
03.4S to 30N, east of 120W including the Gulf of California, and
from the Equator to 30N, between 120W and 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
2045 UTC.

...TROPICAL WAVES...

A western Caribbean tropical wave is along 83W. It extends
southward across the Costa Rica/Panamanian border to the eastern
Pacific waters north of 05N. It is moving westward at 10 kt.
Scattered moderate to isolated strong convection is within 120 nm
either side of the southern part of the wave from 05 to 08N.

A tropical wave is along 96W extending from southeastern Mexico
southward over the eastern Pacific waters to near 04N, moving
westward at about 10 kt. Scattered moderate to isolated strong
convection is within 180 nm west of the wave from 07N to 10N and
from 12N to 15N. Similar activity is within 180 nm east of the
wave from 10N to 13N.

A tropical wave is along 114W from from 05N to 20N, moving
westward at 10 to 15 kt. Scattered moderate to isolated strong
convection is within 120 nm either side of the wave from 12N to
16N and within 60 nm west of the wave from 14N to 16N.

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

The monsoon trough axis extends from 08N75W, west-northwestward
to across northern Panama, to the central portion of Costa Rica
and to 10N85W to 11N98W to 10N110W to 11N117W to 09N129W, where
it transitions to the ITCZ and continues to beyond 10N140W.
Scattered moderate to isolated strong convection is within 180 nm
of the trough between 91W and 93W, and within 60 nm north of
the trough between 98W and 102W. Scattered moderate convection
is within 180 nm south of the trough between 112W and 119W,
between 101W and 105W, also within 120 nm south of the trough
between 124W and 129W and within 60 nm north of the trough
between 123W and 126W.

...OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A broad surface ridge extends southeastward into the region
through 30N129W to offshore of Cabo Corrientes near 17N107W.
Over the offshore waters of the Baja California peninsula,
moderate NW winds prevail. Seas are generally 4 to 6 ft in
moderate period swell except 6 to 7 ft in the areas of strong
winds. Moderate NW to N winds prevail elsewhere to the south
across the Revillagigedo Islands, while moderate NW winds are
across the near shore waters from Cabo Corrientes to Manzanillo.
Light to gentle NW to W winds cover the remaining waters eastward
to Tehuantepec. Seas south of 20N are to 5 ft in long period SW
swell E of 105W and in NW swell W of 105W. Scattered showers and
thunderstorms moving westward are over the waters SW of the Gulf
of Tehuantepec and Chiapas. This activity is present from 11N to
14N between 93W and 103W. Light to gentle S to SW winds are over
the northern part of the Gulf of California while gentle SW to W
winds are over the southern part of the Gulf, and light and
variable winds are over the central portion. Seas are 2 to 4 ft
over the Gulf of California, except to 5 ft in SW swell over the
entrance to the Gulf.

For the forecast, the current Pacific ridge will remain in place
and fluctuate throughout the rest of the week. This pattern will
maintain moderate to fresh NW to N winds over the offshore
waters of the Baja California peninsula, gradually weakening
through Thu. Expect fresh winds near the coast each evening
through Sat. High pressure will strengthen modestly Fri and Sat
to bring a return to moderate to fresh winds. Variable winds less
than 15 kt are expected across the Gulf of California, except
for pulses of moderate W gap winds across southern portions and
fresh SW gap winds N of 30N each evening and night through Thu.

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

Gentle to moderate SW to W winds are occurring south of the
monsoon trough. North of the monsoon trough, moderate or weaker
winds are observed, with moderate easterly gap winds flowing
across the Papagayo region. Seas are 4 to 5 ft in SW swell except
to 6 ft south through west of the Galapagos Islands. Increasing
scattered to numerous showers and thunderstorms are within 90 to
120 nm of the coasts of Panama, Colombia and southern Costa
Rica.

For the forecast, gentle to moderate SW to W winds will continue
south of the monsoon trough near 10N through tomorrow afternoon,
then begin to freshen offshore Thu through Sat. Seas will build
to 5 to 7 ft during this time in a mix of SW swell and westerly
wind swell. Active weather is expected south of 10N Fri into the
weekend. North of 10N, moderate or weaker winds are expected
through Thu evening before the monsoon trough begins to lift
northward, and winds shift to westerly and gradually increase to
gentle to moderate by Sat. Seas will build slightly over the
area waters Thu through Sat as a long fetch of westerly winds
sets up from offshore to 110W, and generates increasing wind
waves moving into the area waters.

...REMAINDER OF THE AREA...

Surface ridging extending from a 1030 mb high centered near
38N157W extends east-southeastward to 30N129W to offshore of
Cabo Corrientes near 17N107W. The pressure gradient between the
ridge and the ITCZ/monsoon trough to the south is forcing
moderate to locally fresh NE trades south of about 25N and west
of 125W. Seas are 5 to 7 ft in mixed NE and SE swell south of
17N west of 133W, and 4 to 6 ft elsewhere.

For the forecast, little overall change is expected over the
open Pacific waters for the next several days as the
aforementioned ridge dominates the region. A weak cold front that
is presently crossing 35N130W will sink southward across 30N
east of 130W tonight into early Thu, then push southeastward
before dissipating by Fri morning. This will induce a slight
decrease in winds during that time period, with winds then
increasing slightly Fri through Sat. SW to W monsoonal winds are
expected to become well established south of 10N and east of 120W
starting tonight through Sat, becoming moderate to fresh. Seas
will build to 6 to 8 ft from 03N to 11N east of 120W during that
time.

$$
Aguirre