417
AXPZ20 KNHC 201601
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Fri Sep 20 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 1200 UTC surface analysis and satellite imagery through
1530 UTC.

...SPECIAL FEATURE...

A Central American Gyre is gradually developing this weekend and
continue through the middle of next week. This scenario, combined
with daytime heating and orographic lifting, is expected to
generate periods of excessive rainfall over southern Mexico and
Central America, as well as the adjacent W Caribbean and E
Pacific waters between 80W and 95W. This activity could produced
dangerous flooding and mudslides across the area. Please follow
the forecasts from your local weather offices for more detailed
information.

...TROPICAL WAVES...

A tropical wave over the far western Caribbean has its axis near
88W and N of 07N, moving westward at about 10 kt. Scattered
moderate convection is noted S of 10N and E of 92W.

A tropical wave has its axis along 105W from 05N to 17N. It is
moving westward at 10 to 15 kt. No significant convection is
noted at this time.

A tropical wave has its axis along 121W from 06N to 18N moving
westward at about 10 kt. No significant convection is
noted at this time.

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

The monsoon trough extends from 11N86W to 10N125W. ITCZ
continues from 10N125W to 10N140W. Aside from the convection
associated with the tropical wave described above, scattered
moderate to isolated strong convection is from 10N to 17N between
92W and 121W, and from 05N to 13N and W of 126W.

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

A broad surface ridge extends southeastward into the region.
Gentle to moderate northwest to north winds are over the Baja
California offshore waters with slight to moderate seas. Along
the Gulf of California, light to gentle winds are ongoing, except
for moderate to fresh SW winds in the northern Gulf N of 29N.
Light to gentle winds and moderate seas are elsewhere.

For the forecast, the surface ridge will remain in place and fluctuate
into the weekend. Gentle to moderate northwest to north winds
over the Baja California offshore waters will increase to fresh
speeds this evening and continue through late Sat night, then
diminish to gentle to moderate speeds afterward into Mon night.
Ongoing moderate to fresh SW winds in the northern Gulf of
California will diminish to gentle speeds Sat and then prevail
through Tue night. An active monsoon trough will support
moderate to fresh W to SW winds across the outer SW Mexican
offshore waters tonight through Tue night. Looking ahead, an
area of low pressure could form well to the southwest of the
southwestern coast of Mexico this weekend. Environmental
conditions appear conducive for some slow development of this
system, and a tropical depression could form by the middle part
of next week while it slowly moves generally northward.
Regardless of development, strong to near gale force winds and
rough seas are forecast to affect the outer offshore waters SW of
Cabo San Lucas starting Mon night and continuing beyond mid
week.

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

Moderate to fresh southwest to west winds are ongoing south of
the monsoon trough and across the Central America offshore waters
S of 10N. Seas are 4 to 6 ft in south to southwest swell. In the
Papagayo region, moderate to fresh NE to E winds are ongoing
along with moderate seas. Gentle to moderate SE to S winds are
observed between the coast of Ecuador and the Galapagos Islands.
Otherwise, scattered moderate convection is over the majority of
the Central America offshore waters. Seas are up to 7 ft in the
areas of strongest convection offshore Costa Rica.

For the forecast, moderate to fresh southwest to west winds
south of the monsoon trough will change little through Sun night,
then increase to fresh to strong speeds across the offshore
waters from Costa Rica to Guatemala Mon through Tue night. Seas
will build during this time in a mix of southwest swell and
westerly wind swell. The monsoonal flow is expected to become
very active, and dominate the region today into early next week.
This pattern will generate increasing westerly wind waves moving
into the area waters. Periods of very active weather are also
expected across the waters north of 06N through the weekend and
possibly into next week.

...REMAINDER OF THE AREA...

Surface ridging extending from a 1027 mb high that is centered
well northwest of the area extends east-southeastward to the Baja
California Peninsula offshore waters. The pressure gradient
between the ridge and the monsoon trough to the south is
resulting in moderate to fresh NE trade winds and moderate seas
S of 22N and W of 130W. South of the monsoon and a 1006 mb low
near 13N98W winds are fresh from the SW and seas to 9 ft in long-
period southeast swell. Seas are 5 to 6 ft in long-period
southerly swell elsewhere S of the monsoon.

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. SW monsoonal winds
will continue to become well established through the weekend as
the monsoon trough lifts very slowly northward. Moderate to fresh
SW winds will generally develop from 05N to 12N and E of 120W
through the weekend. Seas within this wind regime will build to
around 7 to 10 ft E of 120W during that time.

$$
ERA