Tropical Weather Discussion
Issued by NWS
Issued by NWS
855 AXPZ20 KNHC 171629 CCA TWDEP Tropical Weather Discussion...Corrected NWS National Hurricane Center Miami FL 1605 UTC Thu Sep 17 2026 Corrected Special Features section 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 1545 UTC. ...SPECIAL FEATURES...Corrected 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. Winds earlier this morning were at gale-force, but have recently diminished to just below gale-force. Winds may again reach minimal gale force briefly tonight along with seas of 7 to 9 ft. Winds will continue to pulse in the Gulf at fresh to strong speeds through Sat morning, with seas lowering to a peak of around 6 ft. Please read the latest High Seas Forecast issued by the National Hurricane Center at website: https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...TROPICAL WAVES... A tropical wave has is its axis along 97W from 05N northward to extreme southern Mexico. It is moving westward at around 10 to 15 kt. Numerous moderate to isolated strong convection is from 09N to 13N between 90W and 98W. 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 a tropical depression is likely to form late this weekend or early next week while it gradually moves northwestward turning northward off the coast of southwestern Mexico. The axis of a tropical wave is near 115W from 06N to 18N, moving westward at 10 to 15 kt. Numerous moderate to strong convection is seen from 07N to 11N between 111W-119W, and from 12.5N to 16N between 114W and 17W. Environmental conditions appear conducive for gradual development of this system, and a tropical depression is likely to form this weekend or early next week as it moves westward across the western part of the East Pacific. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from along the coast of northwest Colombia west-southwest to across central Costa Rica, then to 10N85W to 07N102W to 10N110W and to 13N121W. Scattered moderate to isolated strong convection is from 02N to 07N between 79W-95W. Scattered moderate convection is within 120 nm north of the trough between 103W-107W, and from 07N to 12N between 117W-121W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see Special Features section above for details on a gale warning for the Gulf of Tehuantepec. An overnight scatterometer satellite data pass generally indicated mostly gentle to moderate northwest winds across the central and southern sections of the Gulf of California. Seas are 2 to 4 ft in the Gulf, except for slightly higher seas of 3 to 5 ft at the entrance due to long-period southwest swell. 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 92W. Moderate to fresh east 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 1005 mb remnant low of Tropical Depression Fifteen-E is located near 15N132W. An overnight 0641Z scatterometer satellite data pass shows fresh to strong northeast winds over the waters to the northwest of the low pressure near 26N. Seas are 7 to 10 ft with these winds per overnight scatterometer satellite altimeter data. Satellite imagery shows numerous strong convection from 14N to 17N between 129W and 135W. Scattered moderate to isolated strong convection is present from 06N tom 09N between 130W and 135W, and from 13N to 18N between 123W and 128W. Scattered moderate convection is within 30 nm of a line from 06N to 09N between 130W and 135W. 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 to ft combined seas in mixed swell are noted elsewhere. For the forecast, environmental conditions appear conducive for gradual development of the tropical wave along 115W, and a tropical depression is likely to form this weekend or early next week as it moves westward across the western part of the East Pacific. Farther west, a broad area of fresh to strong northeast to east winds and moderate to rough seas in north 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 97W. $$ Aguirre