311
AXPZ20 KNHC 221543
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Sun Sep 22 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...

Offshore of Southern Mexico (EP94):
Showers and thunderstorms associated with an area of low pressure
located less than 200 nm south of the coast of southern Mexico
have become better organized since yesterday. Environmental
conditions appear conducive for additional development of this
system, and a tropical depression could form during the next
couple of days while the system drifts slowly northeastward
toward the coast of southern Mexico. The chance for this system
to develop into a tropical cyclone within the next 48 hours is
medium.

A Central American Gyre is gradually developing this weekend and
will 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 produce
dangerous flash flooding and mudslides across the area.
Furthermore, strong to near gale force winds, rough seas and
tstms are forecast to affect the offshore waters between Costa
Rica and El Salvador from Mon night through the end of the week.
Please follow the forecasts from your local weather offices for
more detailed information.

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

The monsoon trough extends from 12N86W to 1005 mb low near
14N98W to 1007 mb low near 14N113W to 11N140W. Scattered moderate
convection is noted from 12N to 19N between 96W and 115W, from
09N to 12N between 121W and 131W, and from 09N to 19N and W of
135W.

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

Refer to the section above for details on EP94 and the developing
Central American Gyre (CAG).

A broad surface ridge extends SE to just west of the Baja California
offshore waters. Moderate to fresh NW winds have diminished to
gentle to moderate speeds over the Baja California offshore
waters and moderate seas are now N of Punta Eugenia. Moderate to
fresh SW to W winds are across the outer offshore waters of S
and SW Mexico associated with a 1008 mb low near 13N99W, which
has the potential for some slow development within the next seven
days. Light to gentle winds are ongoing along the Gulf of
California with slight seas. Otherwise, light to gentle winds and
slight to moderate seas are elsewhere.

For the forecast, surface ridging will remain in place and
fluctuate through today. Gentle to moderate NW winds will
continue over the Baja California offshore waters through Wed
night. Light to gentle winds will prevail along the Gulf of
California through Thu night. An active monsoon trough will
support moderate to fresh W to SW winds across the outer SW
Mexican offshore waters through Mon. Looking ahead, the low
pressure located less than 200 nm south of the coast of southern
Mexico has the potential of becoming a tropical depression
during the next few of days when the system begins to move
slowly eastward or northeastward toward the coast of southern
Mexico. Regardless of development, strong to near-gale force
winds and rough seas are forecast to affect the S and SW Mexican
offshore waters starting Mon night and continuing through the end
of the week.

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

Moderate to fresh SW to W winds are ongoing south of the monsoon
trough and across the offshore waters from Colombia to Costa
Rica along with moderate seas. Gentle to moderate winds and
slight to moderate seas prevail elsewhere. Scattered showers and
tstms are over the offshore waters between Colombia and Costa
Rica due to an active monsoon trough. Strong winds and rough
seas are likely in the regions of strongest convection.

For the forecast, moderate to fresh southwest to west winds south of
the monsoon trough will change little through Mon, then increase
to fresh to near gale force speeds across the offshore waters
from Costa Rica to Guatemala late Mon through Wed night. Seas
will build during this time in mixed swell. The monsoonal flow
is expected to become very active, and dominate the region
through 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 Central America
offshore waters through at least mid week.

...REMAINDER OF THE AREA...

Surface ridging prevails N of 15N and W of 120W. 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
from 12N to 22N and W of 135W. An area of fresh to strong winds
and seas to 8 ft prevails along the monsoon trough from 10N to
15N between 105W and 115W. Gentle to moderate NE to E winds and
moderate seas are noted elsewhere N of the monsoon trough.

For the forecast, southwest monsoonal winds will continue to
become well established through early next week as the monsoon
trough lifts slowly northward. Looking ahead, the low pressure
located less than 200 nm south of the coast of southern Mexico
has the potential of becoming a tropical depression during the
next few of days when the system begins to move slowly eastward
or northeastward toward the coast of southern Mexico. Regardless
of development, strong to near-gale force winds and rough seas
are forecast to affect the S and SW Mexican offshore waters
starting Mon night and continuing through the end of the week.
Another area of low pressure could form well to the southwest of
the southwestern coast of Mexico during the next couple of days.
Environmental conditions appear conducive for some slow
development of this system, and a tropical depression could form
during the middle part of the week while the system moves slowly
eastward or northeastward.

$$
ERA