Tropical Weather Discussion

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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.