Tropical Weather Discussion

Full Alert Message

Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 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 0600 UTC surface analysis and satellite imagery through 0730 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 of 7 to 11 ft. Winds are forecast to diminish below gale-force to later this morning. 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 80W from 03N offshore of the border of Ecuador and Colombia northward to across the Gulf of Panama and Panama and into the western Caribbean Sea, moving westward at around 20 kt. Scattered to numerous moderate and isolated strong convection is noted from 01N to 11N between 77W and 91W. The axis of a tropical wave is near 100W from just south and offshore Guerrero, Mexico southward to near the Equator, moving slowly westward at around 20 kt. Scattered moderate isolated strong convection is noted from 05N to 10N between 95W and 100W. 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 127W from 17N southward to near the Equator, moving westward at around 10 kt. Scattered moderate isolated strong convection is noted from 06N to 14N between 112W and 140W. 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 the SW Caribbean Sea to across Costa Rica, entering the Pacific at the coast near 09.5N84W to 07N110W. The ITCZ extends from 07N110W to 08.5N125W, then resumes west of a tropical wave from 09N131W to beyond 09N140W. Other than the convection described above with three tropical waves, scattered moderate isolated strong is noted from 00N to 06N between 131W and 140W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section above for details on a Gale Warning in effect in the Gulf of Tehuantepec until around sunrise this morning. Please refer to the Tropical Waves section above for information on a tropical wave that has a potential for tropical development offshore Mexico this upcoming weekend. Moderate to fresh NW-N winds are found offshore Baja California from Punta Eugenia northward, locally strong near San Fernando to Punta San Carlos per recent ASCAT data. Fresh to strong E to SE winds are surging up the along the southern to central Gulf of California where a strong thunderstorm complex is present. Scattered to numerous thunderstorms are noted from 21N to 28N between mainland Mexico and Baja California Sur. Seas are 4 to 6 ft across the remainder of the offshore waters, except 1 to 3 ft in the Gulf of California. 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 through this early morning, with moderate to fresh pulses then 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 the southern to central Gulf of California into early today, associated with a complex of convection. Fresh to strong SE winds may pulse in the northern Gulf of California tonight. 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. Fresh to strong winds are in the Gulf of Papagayo per recent ASCAT scatterometer data. Winds are moderate or weaker elsewhere, except moderate to fresh south of the monsoon trough near the Galapagos Islands. Seas are 4 to 7 ft in long-period S to 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 through Thu, with resultant rough seas, then moderate to fresh winds thereafter. 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 south of the monsoon trough will diminish later this morning. Large southerly swell will impact waters mainly from Ecuador to the Galapagos Islands through Thu, largest expected through tonight. ...REMAINDER OF THE AREA... See Tropical Waves section above for information on two tropical waves that have potential for tropical development later this week and into the upcoming weekend. Moderate to fresh E winds are noted from near 10N to 19N between 124W and 138W as seen by recent ASCAT scatterometer data, and is associated with the tropical wave at 127W. Fresh to locally strong winds and seas of around 8 ft are from 09N to 11N between 98W and 103W as seen by ASCAT, and are associated with the tropical wave at 100W. Moderate to fresh winds and rough seas are also found south of 04N between 90W and 140W. Rough seas are south of 04N between 88W and 128W in SE to S swell, except in the lee of the Galapagos Islands. Winds are moderate or weaker across the remainder of the open waters, with seas of 4 to 7 ft. 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, with conditions a bit more tranquil across the open waters by the upcoming weekend.