Eastern North Pacific Tropical Weather Discussion

867 
AXPZ20 KNHC 170303
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Thu Sep 17 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 0000 UTC surface analysis and satellite imagery through
0300 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: The pressure gradient between 
high pressure over southern Mexico and the eastern north Pacific
monsoon trough will support strong to near-gale force N to NE 
gap winds across the Gulf of Tehuantepec through Thu, and will 
reach minimal gale force overnight tonight and briefly Thu night.
Rough seas will accompany these gap winds.

...TROPICAL WAVES...

A tropical wave has been added to the surface map with axis near
99W/100W, from 06N northward to southern Mexico. The wave is 
moving westward at around 10 to 15 kt. Nearby convection is 
discussed in the ITCZ/monsoon trough section below. An area of 
low pressure could form in association to this wave well offshore
of southwestern Mexico within the next few days. Environmental 
conditions appear conducive for some gradual development, and 
this system could become a tropical depression early next week 
while it moves slowly northwestward or northward. There is a low 
chance for development in the next 48 hours, and a medium chance 
for tropical cyclone development within the next 7 days. 

The axis of a tropical wave is near 115W from 07N to 16N, moving
west at 10 to 15 kt. Nearby convection is discussed in the 
ITCZ/monsoon trough section below.

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

The monsoon trough extends from 09N79W to 08N90W to 1007 mb low
pressure near 15N129W to 10N140W. Scattered moderate to isolated
strong convection is noted from 08N to 13N between 90W and 105W.
Scattered moderate convection is active from 12N to 16N between 
110W and 120W.

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

Please see Special Features section above for more on a gale 
warning in the Gulf of Tehuantepec. 

An afternoon scatterometer satellite pass indicated fresh S 
winds over the northern Gulf of California, related to lower
pressure in the region. These winds are likely diminishing this
evening. Gentle to moderate winds and 4-7 ft are noted 
elsewhere, except 1-3 ft in the central and southern Gulf.

For the forecast, please see the Special Features section for 
information about the gale warning in the Gulf of Tehuantepec. 
Elsewhere, gentle to moderate breezes and moderate seas will 
persist. 

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

Fresh to strong easterly winds, and moderate to rough seas, 
prevail across the Gulf of Papagayo region, extending downstream 
to near 90W. Moderate to fresh winds extend downstream from the 
Gulf of Papagayo to the outer offshore waters of El Salvador and 
Guatemala. Elsewhere, moderate or weaker winds and moderate seas 
are noted.

For the forecast, the pressure gradient between a ridge north of
the area and the eastern north Pacific monsoon trough will 
support pulsing fresh to occasionally strong easterly winds and 
moderate to rough seas across the Papagayo region into Thu, then 
pulsing to moderate to fresh thereafter. Moderate winds and seas 
will prevail elsewhere. 

...REMAINDER OF THE AREA...

The 1007 mb remnant low of TD Fifteen-E is centered near 
15N129W. Scattered showers and thunderstorms remain active in the
vicinity of the low. Fresh to strong winds, and rough seas, 
supported by the pressure gradient between the area of low 
pressure and the subtropical ridge north of the area, cover the 
waters from 15N to 25N west of 125W. Gentle to moderate winds 
and 4-6 ft combined seas in mixed swell are noted elsewhere. 

For the forecast, a broad area of fresh to strong NE to E winds
and moderate to rough seas in N swell will persist through the 
remainder of the week from 15N to 25N west of 125W. The 
southerly swell south of 03N will subside below 8 ft by this 
evening. Looking, as described in the tropical wave section
above, there is some potential for tropical cyclone development
associated with a tropical wave near 100W.

$$
Christensen