661
AXPZ20 KNHC 180927
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 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 0600 UTC surface analysis and satellite imagery through
0820 UTC.

...TROPICAL WAVES...

A western Caribbean tropical wave is along 80W-81W and extends
southward across Panama and into the eastern Pacific waters north
of 05N, moving west at 10 kt. Widely scattered clusters of
moderate to strong convection are along the coasts of Colombia,
Panama, and Costa Rica north of 03W and east of 86W.

A tropical wave is along 94W-95W extending from the Isthmus of
Tehuantepec southward over the eastern Pacific waters to near
04N, moving westward at 10 kt. Scattered moderate to strong
convection is described below, and extends between 90W and 96.5W.

A tropical wave is along 111W from 17N to near 06N, moving
westward at about 10 kt. Scattered moderate to strong convection
is noted within 90 nm of the monsoon trough between 108W and
117W.

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

The monsoon trough extends from 10.5N74W to 11.5N83W to 09N95W
to 10.5N117W to 10n132w, where it transitions to the ITCZ, and
continues to 10.5N131W to beyond 10N140W. Scattered moderate
isolated strong convection is noted from 03.5N to 10N E of 86W.
Scattered moderate to strong convection is noted from 06.5N to
18N between 91W and 105W, and from 08N to 12.5N between 108W and
139W.

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

A broad surface ridge extends southeastward into the region
through 30N124W to offshore of Cabo Corrientes near 17N107W.
Over the near and offshore waters of the Baja California
peninsula, moderate NW winds prevail, except for strong winds
along the coast between Punta Eugenia and Cabo San Lazaro. Seas
are 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 sough of 20N are 4 ft in
long period SW swell. Strong thunderstorms cover much of the
nearshore waters of Tehuantepec and Chiapas south to 13N. Recent
satellite scatterometer showed light to gentle W to SW winds
covering most of the Gulf of California tonight, with an area of
moderate westerly gap winds entering the Gulf waters between 24N
and 25N. Seas are 1 to 3 ft, except to 4 ft in SW swell across
the entrance.

For the forecast, the current Pacific ridge will remain in place
and fluctuate throughout the week. This pattern will produce
moderate to fresh NW to N winds over the near and offshore waters
of the Baja California peninsula tonight, gradually weakening
this morning through Thu. Expect fresh winds near the coast each
evening through night. 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 gaps winds N of 30N each evening
and night.

...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 tonight, along about 10N. North of the monsoon
trough, moderate or weaker winds are observed, with moderate
easterly gap winds flowing across the Papagayo region. Seas are
4-5 ft in SW swell except to 6 ft south through west of the
Galapagos Islands. Widely scattered clusters of moderate to
strong thunderstorms are within 75 nm of the coasts from Colombia
to Costa Ric. Earlier scattered strong convection occurring
across the waters of Guatemala and Chiapas has shifted mostly
into the Tehuantepec area.

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 across 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 from a 1031 mb high centered near 38N157W
extends east-southeastward to 30N124W 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 28N and west of 125W, with
strongest from 10N to 18N west of 135W. Seas are 6-8 ft in mixed
swell south of 17N west of 133W, and 4-6 ft elsewhere.

For the forecast, little overall change is expected over the
open Pacific waters for the next several days, as the ridge
dominates the region. A weak cold front will sink across 30N east
of 130W Wed night and 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 late Wed through Sat,
becoming moderate to fresh. Seas will build 6 to 8 ft from 03N to
11N east of 120W during that time.

$$
Stripling