337
AXPZ20 KNHC 160341
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Sun Jun 16 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 0000 UTC surface analysis and satellite imagery through
0330 UTC.

...SPECIAL FEATURES...

Central America and southern Mexico Heavy Rainfall Event: A
broad area of low pressure has developed over northern Central
America and southern Mexico. This weather pattern, known as a
Central American Gyre (CAG), enhances moist SW flow off the
Pacific and into the coastal terrain of Central America and
southern Mexico. This moist flow can persist for several days,
resulting in life- threatening conditions that include flooding
and mudslides. Numerous heavy showers and thunderstorms have been
ongoing for hours today along the coast of Guatemala and the
Mexican state of Chiapas. The pattern is expected to persist
through at least the middle of next week across northern Central
America and southern Mexico, with the threat to life and property
increasing as the event persists. The main areas impacted by the
heavy rainfall will be northwest Nicaragua, southwest Honduras
northwest Nicaragua, and coastal sections of Honduras, El
Salvador, Guatemala, and the Mexican state of Chiapas. Farther
south, the moist southwest flow was also causing persistent heavy
rainfall across Costa Rica and Panama, although this will be
diminishing Sun as the focus shifts northward to northern Central
America.

The persistence of the moist pattern and strong onshore flow
will create very hazardous conditions to the region and could be
life-threatening. Please refer to your local meteorological
office bulletins for more detailed information.

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

The monsoon trough is displaced farther north than usual due to
the ongoing Central American Gyre. It extends off the coast of
Mexico near 16N99W to 12N117W to 08N125W. The ITCZ extends from
08N125W to beyond 07N140W. Numerous moderate to isolated strong
convection is noted from 13N to 17N between 92W and 97W.
Scattered moderate convection is noted from 04N to 16N between
79W and 110W.

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

Refer to the section above for details on the Central American
Gyre.

A large cluster of showers and thunderstorms is active off
Chiapas in southern Mexico, associated with a broad area of low
pressure over the region known as the Central American Gyre.
These thunderstorms are probably causing widespread lightning,
gusty winds and locally rough seas off Chiapas. Meanwhile,
moderate to fresh NE to E winds are noted in this region with
seas 6 to 7 ft.

Farther north, fresh to strong NW winds continue to approach
the waters just west of Guadalupe Island off Baja California
Norte. Combined seas are 8 to 11 ft north fo Punta Eugenia,
primarily due to NW swell. These winds and seas are influenced by
their portion between 1029 mb high pressure near 35N140W and
lower pressure over the lower Colorado River valley. Mostly
gentle to moderate breezes and slight to moderate seas persist
elsewhere with 5 to 7 ft seas.

For the forecast, fresh to strong winds and rough seas will
persist off Baja California Norte through Mon, primarily beyond
120 nm offshore. Large swell of 8 to 12 ft will move into the
waters off Baja California today, and persist mainly north of
Cabo San Lazaro into mid week before subsiding by Wed.
Meanwhile, off southern Mexico, expect fresh SW winds and
building seas starting tonight off Chiapas as a broad area of low
pressure, continues to develop over southern Mexico and northern
Central America. Winds and seas will increase further off
Chiapas and Oaxaca through the early part of the week as the
Central American Gyre intensifies and persists.

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

With the monsoon trough displaced farther north than usual, this
is bringing fresh winds across the Guatemala, El Salvador and
Nicaragua offshore waters. Seas are 7 to 8 ft in this area within
S to SW swell. Across the rest of the Central American offshore
waters, winds are moderate with 5 to 7 ft seas. Strong
thunderstorms continue to impact mainly northern Central America
off Guatemala, bringing heavy rain and frequent lightning. These
storms could cause hazardous marine conditions. In the Ecuador
and Galapagos Island offshore waters, winds are moderate to
locally fresh. Seas are 5 to 7 ft within S swell.

For the forecast, the broad area of low pressure known as a Central
American Gyre will cause an increase in winds, rough seas and
widespread showers and thunderstorms across much of offshore
waters through mid week. Conditions will continue to improve over
the Gulf of Panama tonight. Farther south, seas to 8 ft in S
swell will continue around the Galapagos Islands through Tue.

...REMAINDER OF THE AREA...

Broad ridging dominates the waters north of the ITCZ and monsoon
trough, anchored by a 1030 mb high pressure near 35N140W.
Moderate to fresh winds prevail across waters north of the
monsoon trough and west of 115W with seas 6 to 9 ft. East of
115W, gentle to moderate winds are noted south of the monsoon
trough to 05N. Seas are 5 to 7 ft across the rest of the Pacific
waters. Fresh to strong winds are beginning to filter through the
far northeastern waters, N of 26N between 119W and 129W with
seas 8 to 11 ft within NW swell.

For the forecast, strengthening high pressure centered NW of the
area will dominate waters west of 120W into the weekend. Fresh to
strong winds from the California Channel Islands southward are
likely to dip south of 30N at times through early next week.
Seas will build to 8 to 12 ft by Sun night into Mon, mainly north
of 20N between 120W and 130W. SW flow south of the monsoon
trough is forecast to continue tonight between 90W and 115W,
supporting seas of 6 to 8 ft. Similar winds and seas are likely
to return there by the end of the weekend into early next week.
Thunderstorms will persist near the monsoon trough and east of
110W or so through the next couple of days. Seas to 8 ft will
hover around 03S near the Galapagos Islands through the weekend.

$$
AReinhart