971
AXPZ20 KNHC 202107
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 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 1800 UTC surface analysis and satellite imagery through
2100 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
89W and N of 07N, moving westward at about 10 kt. Scattered
moderate convection is noted within 240 nm on either side of the
wave mainly S of 10N.

A tropical wave has its axis along 106W 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 123W from 04N to 16N moving
westward at about 10 kt. Scattered showers prevail along the wave
axis near 11N.

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

The monsoon trough extends from 11N86W to a 1008 mb low near
13N98W to 11N121W. ITCZ continues from 11N125W to 10N140W. Aside
from the convection associated with the tropical waves described
above, scattered moderate to isolated strong convection is from
07N to 15N between 90W and 126W, and from 06N to 14N and W of
134W.

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

A broad surface ridge extends southeastward into the region.
Gentle to moderate northwest winds are over the Baja California
offshore waters with slight 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 30N. Light to gentle winds
and slight seas are elsewhere.

For the forecast, the surface ridge will remain in place and
fluctuate into the weekend. Gentle to moderate northwest 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 during the next few days 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 through the 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, with moderate seas. Gentle to moderate winds and
slight seas prevail elsewhere. 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 the
weekend, 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 mixed swell. The
monsoonal flow is expected to become very active, and dominate
the region through 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 1028 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 trough, fresh SW winds
prevail with moderate seas in long-period southeast swell. Slight
seas 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 slowly northward. 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 during the next few
days while it slowly moves generally northward.

$$
ERA