871
AXPZ20 KNHC 232203
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 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 1800 UTC surface analysis and satellite imagery through
2130 UTC.

...SPECIAL FEATURES...

Recently upgraded Hurricane John is centered near 15.5N 98.5W at
23/2100 UTC, moving north at 5 kt. Estimated minimum central
pressure is 973 mb. Maximum sustained wind speed is 85 kt with
gusts to 105 kt. Hurricane-force winds extend outward up to 10
NM from the center and tropical-storm-force winds extend outward
up to 40 NM. Seas 12 ft or greater are occurring within 75 NM in
the southern semicircle, within 60 NM in the northeast quadrant
and within 45 NM in the northwest quadrant, with peak seas near
16 ft. Strong convection is occurring within 90 NM of the center,
except within 150 NM to the east of the center. Rapid
strengthening is forecast, and John is expected to become a major
hurricane before the center reaches the coast of southern Mexico
on Tuesday. John will move to 16.0N 98.3W Tue morning, inland to
16.5N 98.3W Tue afternoon, move inland and weaken to a tropical
depression near 16.7N 98.4W Wed morning, and dissipate Wed
afternoon. Through Thursday, 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. 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 will generate periods of excessive
rainfall over southern Mexico and Central America this week, as
well as the adjacent western Caribbean and eastern Pacific waters
between 80W and 95W. This scenario, combined with daytime
heating and orographic lifting, 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
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 a 1007 mb low centered near
16N107W to 13N115W to 12N140W. Away from convection related to
Hurricane John and the Central American Gyre, scattered moderate
convection is noted from 08N to 12N between 124W and 137W.

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

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

A 1027 mb high is centered near 38N138W, and surface ridging
extends through the Baja California offshore waters. This pattern
is allowing for gentle to moderate NW breezes and slight to
moderate seas. Recent scatterometer satellite data showed locally
fresh NW winds north of Punta Eugenia. Light to gentle winds
continue in the Gulf of California with seas of 1-3 ft, locally
up to 4 ft in the entrance to the Gulf. Fresh to near strong
winds are likely occurring in the periphery of Hurricane John
with seas of 8-10 ft.

For the forecast away from Hurricane John, high pressure will
become anchored near 20N140W through Tue, leading to gentle to
moderate N winds in the offshore waters. By Wed, the pressure
gradient between the persistent high pressure and falling
pressure in the southwestern United States will support fresh NW
winds and seas of 5-7 ft in the Mexican offshore waters, likely
occurring into the upcoming weekend.

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

Please refer to the Special Features section above for
information on the Central American Gyre (CAG).

Recent scatterometer data depict moderate to fresh SW winds
offshore of Panama and Costa Rica as well as in the periphery of
Hurricane John in the offshore waters of Guatemala, with gentle
to moderate winds occurring elsewhere. Recent altimeter data
show seas of 5-8 ft offshore of Guatemala near Hurricane John,
and seas of 4-7 ft in the rest of the waters. Moderate to strong
convection is occurring from 05N to 10N between 81W and 90W,
including in the waters off the coasts of Panama and Costa Rica.
Strong winds and rough seas will occur near convection.

For the forecast, moderate to fresh SW winds will continue in the
wake of Hurricane John off the coast of Central America through
tomorrow, with fresh to strong winds occurring off the coast of
Guatemala through Nicaragua into Thu. Increasing W swell will
expand eastward in the wake of the hurricane, moving through the
waters of Guatemala tonight, expanding farther east toward El
Salvador on Tue, and toward Nicaragua Wed. Periods of strong
convection will also occur over most of the Central America
offshore waters through at least mid-week.

...REMAINDER OF THE AREA...

High pressure is anchored near 38N138W, with gentle to moderate
N to NE winds occurring along the periphery of the ridge. Locally
fresh NE winds are noted north of 28N between 130W and 135W with
associated seas of 6-8 ft. Elsewhere, fresh to locally strong SW
winds prevail south of the monsoon trough east of 125W and north
of 09N.

For the forecast, SW winds become well established south of the
monsoon trough as the trough slowly lifts northward over the next
few days. Fresh to strong SW winds will occur generally north of
09N and east of 110W through Wed, with strong SW winds
continuing east of 105W through at least Fri. Rough seas will
accompany these gusty winds. Looking ahead, a trough of low
pressure located several hundred miles southwest of southwestern
Mexico is producing limited shower and thunderstorm activity.
Environmental conditions only appear marginally favorable for
gradual development of this system while it moves slowly eastward
to the south of the coast of Mexico through the middle of this
week.

$$
ADAMS