023
AXPZ20 KNHC 190932
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Thu Sep 19 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
0830 UTC.

...TROPICAL WAVES...

A western Caribbean tropical wave is along 82W-83W, extending
southward across the Costa Rica/Panamanian border to the eastern
Pacific waters north of 05N. It is moving west at 5 kt.
Scattered moderate to strong convection described below covers
the Pacific waters N of 07.5N and inland across Central America E
of 91W.

A tropical wave is along 98W-99W, extending from southeastern
Mexico southward over the eastern Pacific waters to near 04N,
moving west at about 10 kt. Scattered to locally numerous moderate
to strong convection described below is N of 07.5N to coastal
Mexico between 93W and 102W.

A tropical wave is along 116W-117W from from 05N to 19N, moving
west at 10 kt. Scattered moderate isolated strong convection
described below is from 07.5N to 13.5N between 110W and 120W.

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

The monsoon trough axis extends from 10.5N73W to 10.5N96W to
11.5N104W to 08.5N126W to 10N140W. Scattered to locally numerous
moderate to strong convection is noted from 03.5N to 07.5N E of
79W, from 07N to 16.5N between 82W and 111W, and from 07.5N to
13.5N between 111W and 129W. Scattered moderate isolated strong
convection is noted from 07.5N to 14N between 134W and 140W.

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

A broad surface ridge extends southeastward into the region
through 27N130W to offshore of SW Mexico near 17N108W. Over the
near and offshore waters of Baja California, gentle to moderate
NW winds prevail, and extend southward to 20N, except for fresh
winds near the coast between Punta Eugenia and Cabo San Lazaro.
South of 20N through the Revillagigedo Islands and to Michoacan,
Mexico, gentle winds gradually become nw to N. Seas are
generally 4 to 5 ft in moderate period swell except to 6 ft in
the areas of fresh winds. Light to gentle W to SW winds cover
the remaining waters eastward to Tehuantepec. Seas south of 20N
are to 4 to 5 ft in long period SW swell E of 105W and in NW
swell W of 105W. Scattered showers and thunderstorms continue to
shift SW off the coast and over the coastal waters within 150 nm
of the Mexican coast between Tehuantepec and Colima. Light to
gentle S to SW winds are over the north and central portions of
the Gulf of California, with moderate W to SW gap winds occurring
across typical locations over northern and southern sections of
the Gulf. Seas are 1 to 3 ft over the Gulf of California, except
3 to 4 ft in SW swell over the entrance to the Gulf.

For the forecast, the current Pacific ridge will remain in place
and fluctuate into the upcoming weekend This pattern will
maintain moderate NW to N winds over the offshore waters of Baja
California tonight, gradually weakening through Thu afternoon.
Expect fresh winds near the coast each evening. 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 Fri.

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

Gentle to moderate SW to W winds prevail south of the monsoon
trough, along about 10N-11N. North of the monsoon trough,
moderate or weaker winds are observed. Seas are 4 to 5 ft in SW
swell except to 6 ft south through west of the Galapagos Islands.
A nearly solid line of strong thunderstorms has moved westward
off the coasts from southern Costa Rica to El Salvador and
Guatemala during the past few hours, producing frequent
lightning and gusty easterly winds. This activity continues at
this time.

For the forecast, gentle to moderate SW to W winds will continue
south of the monsoon trough near 11N, through this afternoon,
then begin to freshen offshore through Sat. Seas will build to 5
to 7 ft during this time in a mix of SW swell and westerly wind
swell. North of 11N, 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. The monsoonal flow is expected to
become very active, and dominate the region into early next
week, as a long fetch of westerly winds sets up from the offshore
waters to 110W. This pattern will generate increasing westerly
wind waves moving into the area waters. Active weather is also
expected across area waters N of 06N Fri through the weekend.

...REMAINDER OF THE AREA...

Surface ridging extending from a 1028 mb high centered near
38N158W extends east-southeastward through 27N130W to offshore
of SW Mexico near 17N108W. The pressure gradient between the
ridge and the monsoon trough to the south is forcing moderate NE
trades south of about 25N and west of 130W. Seas are 5 to 6 ft
in mixed NE and SE swell south of 25N west of 125W, 5 to 8 ft
south of the monsoon trough from 03N to 10N between 90W and 120W,
and 4 to 5 ft elsewhere.

For the forecast, little overall change is expected over the
open Pacific waters W of 120W for the next several days as the
aforementioned ridge dominates the region. A weak cold front that
is presently crossing 32N126W will sink southward across 30N
east of 130W today, 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 Sun. SW to W monsoonal winds are expected to become well
established this afternoon through the weekend, as the monsoon
trough lifts very slowly northward. Moderate to fresh SW to W
winds, with small areas of locally strong winds near active
thunderstorms, will develop from 05N to 12N and E of 120W Thu
night through the weekend. Seas within this wind regime will
build to 6 to 9 ft east of 120W during that time.

$$
Stripling