Tropical Weather Discussion

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Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Tue Aug 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 0000 UTC surface analysis and satellite imagery through 0100 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A very tight local pressure gradient is present over the Gulf of Tehuantepec area in the wake of a departing tropical wave with a tight ridge of high pressure nosing down eastern to southeastern Mexico, as well as a surface trough to the northeast over the western Yucatan Peninsula. This pressure is likely supporting minimal gale-force northerly gap winds in the Gulf of Tehuantepec, with seas in the process of building to 8 to 10 ft. Winds are forecast to diminish below gale-force to fresh to strong by early Tue. Please, refer to the latest NWS High Seas Forecast available at website: https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...TROPICAL WAVES... The axis of a tropical wave is near 78W from 03N near the border of Ecuador and Colombia northward to across eastern Panama near the border with Colombia, and continuing into the Caribbean Sea to near western Jamaica, moving westward at around 10 kt. Scattered to numerous moderate and isolated strong convection is noted from 02N to 12N between 77W and 93W. The axis of a tropical wave is near 98W from just western offshore Oaxaca southward to near the Equator, moving slowly westward at around 5 kt. Scattered moderate isolated strong convection is noted from 06N to 13N between 96W and 103W. An area of low pressure is forecast to form several hundred nautical miles south of the coast of southern Mexico around the end of the week. Gradual development of this system is likely thereafter, and a tropical depression is expected to form this weekend while the system moves west- northwestward, remaining well offshore of Mexico. The axis of a tropical wave is near 126W from 01N to 17N, moving westward at around 10 kt. Scattered moderate isolated strong convection is noted from 06N to 14N between 114W and 136W. A broad area of low pressure is expected to form well to the east- southeast of the Hawaiian Islands during the latter part of this week. Environmental conditions appear conducive for gradual development of this system, and a tropical depression could form towards the end of the week or over the weekend while the system moves generally westward across the western portion of the east Pacific and into the central Pacific. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 1009 mb low pressure near the border of NW Venezuela and northern Colombia at 09N72W to along northern Panama to across Costa Rica and into the Pacific near 09N84W to 06.5N108W. The ITCZ extends from 06.5N108W to 08.5N122W, then resumes west of a tropical wave from 09N129W to beyond 08N140W. Other than the convection described above with three tropical waves, scattered moderate isolated strong is noted from 00N to 02.5N between 129W and 138W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features section above for details on a Gale Warning in effect in the Gulf of Tehuantepec for the overnight hours. An area of 7 to 9 ft seas is found just southwest of the Gulf of Tehuantepec, a combination of earlier fresh to strong winds to the east near the Gulf of Papagayo, the Gulf of Tehuantepec winds, and background SW swell. See Tropical Waves section above for information on a tropical wave that has a potential for tropical development offshore Mexico at the end of this week. Seas are 4 to 6 ft across the remainder of the offshore waters, except 1 to 3 ft in the Gulf of California. Moderate to fresh NW-N winds are found offshore Baja California from Punta Eugenia northward, locally strong near Punta Eugenia. Winds are moderate or weaker across the remainder of the offshore waters, except developing fresh to strong winds along the coast between Cabo Corrientes and the entrance to the Gulf of California where a strong thunderstorm complex is in the process of moving slightly offshore into the Gulf of California and adjacent areas. Scattered thunderstorms are noted from 19N to 27N between Mexico and 109.5W. For the forecast, the pressure gradient between high pressure over the Gulf of America and relatively lower pressure south of Mexico will continue to induce pulses of strong north winds over the Gulf of Tehuantepec through Wed night, to minimal gale-force overnight tonight into early Tue, with moderate to fresh pulses starting Thu. Seas will occasionally build to rough with the fresh to strong or stronger winds. A surge of strong SE winds will move from north of Cabo Corrientes into the southern and central Gulf of California tonight into early Tue, associated with a complex of convection. Winds and seas may build across the outer offshore waters of southwestern Mexico by the end of the week into the upcoming weekend in association with a possibly developing area of low pressure beyond the offshore waters. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... See Tropical Waves section above for information on a tropical wave producing heavy rainfall over portions of Colombia, Panama and areas northwestward, with heavy thunderstorms also over the adjacent offshore waters as described above. Developing offshore easterly fresh to strong winds are in the immediate Gulf of Papagayo. Winds are moderate or weaker elsewhere north of the monsoon trough, and moderate to fresh south of the monsoon trough. Seas are 4 to 7 ft in long-period SW swell, except 7 to 9 ft southwest of the Galapagos Islands. For the forecast, the pressure gradient between high pressure over the western Caribbean and relatively lower pressure over Central America will lead to pulsing strong to near gale-froce northeast to east gap winds over the Papagayo region, with resultant rough seas. Moderate to fresh associated winds will extend well downwind across the outer offshore waters of El Salvador and Guatemala at times. Moderate to fresh southerly winds will pulse south of the monsoon trough through tonight. Large southerly swell will impact waters mainly from Ecuador to the Galapagos Islands through Wed night, largest expected through Tue night. ...REMAINDER OF THE AREA... See Tropical Waves section above for information on two tropical waves that have potential for tropical development later this week. Moderate to fresh E winds are noted from 09N to 20N between 121W and 136W associated with the tropical wave at 126W, with similar winds from 20N to 28N between 129W and 138W. Moderate to fresh winds and rough seas are also found south of the monsoon trough between 90W and 126W. Winds are moderate or weaker across the remainder of the open waters, except locally fresh near the eastern tropical wave at 98W with locally rough seas. Seas are 4 to 7 ft across the remainder of the open waters. For the forecast, regardless of tropical development, the tropical waves described in the above section will bring some increasing winds and seas to area waters. Away from these waves, little change is expected in marine weather through the week.