594
AXPZ20 KNHC 231015
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Mon Sep 23 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
1000 UTC.

...SPECIAL FEATURE...

Recently upgraded Tropical Storm John is near 14.4N 98.5W at
23/0900 UTC, moving north-northeast at 3 kt. Estimated minimum
central pressure is 1000 mb. Maximum sustained wind speed is 40
kt with gusts to 50 kt. Satellite imagery shows increased very
cold cloud tops over the center of the depression and increased
banding features coiling around the center of the system. The
very deep convection consists of the numerous strong type
intensity within 60 nm of the center, and within a wide band
from 14N to 17N between 100W and 102W. Numerous moderate to
isolated strong convection is seen elsewhere from 11N to 17N
between 96W and 102W. The coldest cloud top temperatures are in
the range of -75 to -83 degree Celsius. Tropical Storm John is
forecast to continue north-northeast or northeastward for the
next couple of days. On the forecast track, the center of the
this system is forecast to approach the southern coast of Mexico
during the next day or two and move inland on Tue or Wed. John
is forecast to strengthen over the next day or two, and could
become a hurricane before landfall. Through Thu, John is expected
to produce 6 to 12 inches of rain with isolated totals around 15
inches across the coastal areas of Chiapas. In areas along and
near the Oaxaca coast to southeast Guerrero, between 10 and 20
inches of rain with isolated totals near 30 inches can be
expected through Thursday. This heavy rainfall will likely cause
significant and possibly catastrophic, life-threatening flash
flooding and mudslides to the Mexican States of Chiapas, Oaxaca,
and southeast Guerrero, particularly in areas near the coast. A
dangerous storm surge is expected to produce significant coastal
flooding near and to the east of where the center makes landfall.
Near the coast, the surge will be accompanied by large and
destructive waves. wells associated with John are forecast to
begin to affect the coast of southern Mexico later today, with
the potential for dangerous surf and rip currents much of the
week. Please see local statements for more information.

Please read the latest HIGH SEAS FORECAST issued by the National
Hurricane Center at website -
https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and the latest
John NHC Forecast/Advisory and Public Advisory at
www.hurricanes.gov for more details.

A Central American Gyre is forecast to continue to gradually
develop through the middle of the upcoming 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 western Caribbean
and eastern 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 thunderstorms  are forecast to affect the offshore waters
between Costa Rica and El Salvador from tonight 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 axis extends from northwest Colombia westward
to northern Costa Rica, and to 11N86W to 14N96W. It resumes at
16N102W and continues to low pressure of 1007 mb near 16N110W to
11N124W and to beyond 12N140W. Aside convection related to
recently upgraded Tropical Storm John, scattered moderate to
isolated strong convection is within 60 nm north of the
trough between 86W and 90W.

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

Please refer to the Special Features section above for
information on both Tropical Storm John and on the developing
Central American Gyre (CAG).

A broad surface ridge extends southeastward to just west of the
Baja California offshore waters. The related gradient is allowing
for generally gentle to moderate northwest winds to exist over
the Baja California offshore waters. Moderate seas are north
of Punta Eugenia. Light to gentle winds are ongoing along the
Gulf of California with slight seas. Moderate to fresh winds are
noted in the vicinity of Tropical Storm John, with seas to 10
ft. Otherwise, light to gentle winds and slight to moderate seas
are elsewhere.

For the forecast, recently upgraded Tropical Storm John is near
14.4N 98.5W, or about 110 nm south of Punta Maldonado, Mexico at
2 AM PDT moving north-northeast at 3 kt. Maximum sustained winds
are 40 kt with gusts to 50 kt, and the minimum central pressure
is 1000 mb. Tropical Storm John will strengthen some as it moves
to near 14.8N 98.2W this afternoon, to near 15.4N 97.6W late
tonight with maximum sustained winds 60 kt gusts 75 kt, to near
15.8N 97.2W Tue afternoon, and inland to near 16.0N 97.0W late
Tue night and dissipate Wed afternoon. Otherwise, high pressure
will remain in place through mid-week. Gentle to moderate
northwest winds will continue over the Baja California offshore
waters through Wed night. Light to gentle winds will continue
over the Gulf of California through the period, with occasional
instances of gentle to moderate winds in the central section.

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

Moderate to fresh southwest to west winds are 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
thunderstorms are over the offshore waters between northern
Costa Rica and El Salvador 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 be at mostly fresh speeds from
tonight through Thu, then at moderate speeds afterward. The
monsoonal flow is expected to become very active, and dominate
the region through the week. This pattern will generate
increasing westerly wind waves moving into the area waters.
Periods of very active weather are also expected over most of the
Central America offshore waters through at least mid week.

...REMAINDER OF THE AREA...

High pressure is generally present north of about 15N and west of
115W. The gradient between the high pressure and a 1008 mb low
just west of the area near 12N142W is supporting fresh winds and
seas to 8 ft in decaying south swell from about 11N to 14N and
west of 139W. Moderate to fresh trade winds and moderate seas are
north of 15N per an overnight ASCAT satellite data passes over
that part of the area. An area of fresh to strong winds and seas
of 8 to 9 ft prevails near the monsoon trough from 08N to 15N
between 98W and 105W. Gentle to moderate trade winds along with
moderate seas are noted elsewhere north of the monsoon trough.

For the forecast, southwest monsoonal winds will continue to
become well established through the next couple of days as the
monsoon trough lifts slowly northward. Looking ahead, environmental
conditions only appear marginally favorable for slow development
of a trough of low pressure that is located several hundred miles
west-southwest of southwestern Mexico as t moves slowly eastward
to the south of the coast of Mexico through the middle of this
week.

$$
Aguirre