Eastern North Pacific Tropical Weather Discussion

734 
AXPZ20 KNHC 170832
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 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 0600 UTC surface analysis and satellite imagery through
0830 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
into Fri. A recent scatterometer satellite pass confirmed gale force
winds across the Gulf of Tehuantepec, and this may persist into the
early morning. Winds may again reach minimal gale force briefly tonight.
Rough seas will accompany these gap winds. Winds and seas will diminish
Fri.

...TROPICAL WAVES...

A tropical wave is along 101W, from 06N northward to southern 
Mexico, 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 high chance for tropical cyclone development within the next 7 
days. 

The axis of a tropical wave is near 116W 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 convection
is active from 02N to 06N east of 83W, and from 10N to 16N
between 112W and 116W. Scattered moderate to isolated strong
convection from 08N to 13N between 90W and 100W.

...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. 
Gentle to moderate breezes and moderate seas will persist 
elsewhere through the end of the week. Meanwhile, a tropical 
wave is producing disorganized showers and thunderstorms south of
Acapulco. Looking ahead, environmental conditions appear 
conducive for gradual development, and there is a high chance a 
tropical depression may form late this weekend or early next 
week while it moves north- northwestward or northward at 5 to 10 
kt off southwest Mexico.

...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. 

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 today, 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 
15N130W. 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. Moderate to fresh winds,
seas to 7 ft, a scattered showers and thunderstorms are also
active near a 1008 mb low pressure area along the monsoon trough
near 12N112W. Gentle to moderate winds and 4-6 ft combined seas 
in mixed swell are noted elsewhere. 

For the forecast, environmental conditions appear conducive for 
gradual development of the 1008 mb low pressure near 12N112W, 
and a tropical depression could form this weekend as the system 
moves westward at around 10 kt. 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. Farther
west, 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. Also, as described in the 
tropical wave section above, there is some potential for tropical
cyclone development associated with a tropical wave near 101W.

$$
Christensen