000
AXPZ20 KNHC 181559
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Mon May 18 2026

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
1500 UTC.

...SPECIAL FEATURES...
Significant Swell Event West of Baja California Norte: 
Very large, long-period NW swell is maintaining very rough seas
of 12 to 15 ft, north of 26N between 117W and 127W, including
waters near Guadalupe Island. This swell will gradually decay and
retreat northward through late Tue, which should allow seas to
subside below 12 ft by late this evening.

Please refer to the latest High Seas and Offshore Waters 
Forecasts issued by the National Hurricane Center at websites: 
https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and
https://www.nhc.noaa.gov/marine/offshores_eastpac.php for more 
details.

...TROPICAL WAVES...

A tropical wave is near 81W from the western Caribbean Sea
southward across Panama into the eastern Pacific, and moving 
west at 5 to 10 kt. It is enhancing convection near the monsoon
trough described in the section below.

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

A monsoon trough extends west-southwestward from central Costa
Rica to 07N96W. An ITCZ continues westward from 07N96W to 07N120W
to beyond 08N140W. Scattered moderate to strong convection is 
active near and south of the monsoon trough from 02N to 08N east 
of 87W, including offshore waters of Costa Rica, Panama and 
Colombia. Scattered moderate convection is seen near the ITCZ and
rest of the monsoon trough from 03N to 11N between 90W and 99W. 
Numerous moderate to scattered strong convection is present near 
the western part of the ITCZ from 01N to 11N west of 120W.

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

Please read the Special Features section above regarding  
Significant NW swell.

Low pressure is moving eastward over the Colorado River Valley 
in between higher pressure over the eastern Pacific and northwest
Mexico. This pattern is supporting strong to near-gale force SW
gap winds across the northern Gulf of California. These winds
have diminished slightly from gale-force winds earlier this
evening. Moderate to rough seas are associated with these gap
winds across the northern Gulf. The pattern is also supporting
fresh NW winds off Baja California Norte, as noted in recent
scatterometer satellite data. Concurrent altimeter satellite and
Sofar buoy data confirmed the large swell off Baja California
mentioned in the Special Features section, with 10-13 ft 
combined seas north of Cabo San Lazaro. Gentle breezes are noted 
elsewhere. Seas are 6-9 ft off Baja California off Baja 
California Sur south of Cabo San Lazaro, 4-6 ft elsewhere off 
southern Mexico, and 1-3 ft over the central and southern Gulf of
California.

For the forecast, a trough moving across the Colorado River 
Valley and higher pressure over northwestern Mexico and the 
eastern Pacific are altogether supporting fresh SW to NW gap 
winds in the northern Gulf of California this morning. This is 
also supporting moderate to fresh NW winds off Baja California 
Norte. Winds in both areas will subside to between gentle and 
moderate later this afternoon. In addition, very large and long- 
period NW swell will maintain very rough seas off Baja California
Norte through this afternoon, then subside to rough this evening
through Tue. Rough seas will also linger near Baja California 
Sur through Tue. Gentle to moderate winds and moderate seas will 
persist elsewhere through Fri.
 
....OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA,
AND WITHIN 750 NM OF ECUADOR...

A recent scatterometer satellite pass indicated fresh gap winds
downwind of the Gulf of Papagayo, and north of a broad
circulation along the monsoon trough centered near 09N88W. Gentle
breezes and 3-5 ft seas are noted elsewhere primarily with SW
swell. Scattered showers and thunderstorms are active south of
Panama near the tropical wave.

For the forecast, fresh easterly gap winds in the Papagayo 
region will pulse to strong during the night-time hours through 
Wed night. Elsewhere, gentle to moderate winds along with 
moderate seas in southerly swell are expected through most of 
this week. Scattered heavy showers and isolated thunderstorms
near the monsoon trough will linger in the offshore waters of 
Costa Rica, Panama and Colombia today.

...REMAINDER OF THE AREA...

A broad ridge covers the waters north of 20N, anchored by 1033 mb
high pressure centered near 40N138W. Fresh to strong NW to N 
winds and large NW swell cover the waters north of 20N and east 
of 130W. Fresh to strong NE to E winds and 8-9 ft seas are noted 
north of 10N west of 125W. Gentle to moderate breezes are noted 
elsewhere. Seas are 6-8 ft in S swell south of 10N and west of 
120W, with 5-7 ft seas in a mix of NW and SW swell elsewhere over
the tropical Pacific. Trade wind convergence is supporting scattered
showers and thunderstorms are active from 08N to 10N west of 
125W.

For the forecast, the aforementioned ridge should gradually
weaken while retreating northward today. This will allow winds 
and seas north of the ITCZ to steadily subside from east to west 
through midweek, becoming gentle to moderate winds with 6-8 ft 
seas by Thu. Winds south of the ITCZ will also becoming gentle by
Thu with higher seas at 5-7 ft in mixed swells.

$$

Chan