Tropical Weather Discussion

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Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Thu Aug 20 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...TROPICAL WAVES... The axis of a tropical wave is entering eastern portions of the Tropical Pacific basin along 80W, north of 04N, moving westward at 15 to 20 kt. Scattered to numerous moderate to strong convection is noted from 04.5N to 11N between 77W and 86W. The axis of a tropical wave is near 98W from 05N to 18N, moving westward at 15 to 20 kt. Scattered to locally numerous moderate to strong convection stretches from 06N to 14.5N between 90W and 105W. Environmental conditions appear favorable for gradual development, and a tropical depression is likely to form this weekend while the system moves generally west-northwestward, remaining well offshore of Mexico. This system has a low chance of tropical cyclone formation in the next 48 hours, and a high chance in the next 7 days. Regardless of development, expect increasing winds and seas will impact the outer offshore waters of southwestern Mexico. The axis of a tropical wave is near 112W from 05N to 16N, moving westward at around 15 to 20 kt. A broad area of low pressure associated with this tropical wave near 09.5N111.5W is producing scattered to numerous moderate to strong convection from 04N to 12N between 107W and 117W. Fresh to locally strong winds are found within 120 nm of the N semicircle to the low, with locally rough seas there. Environmental conditions are forecast to be marginally favorable for gradual development of this system over the weekend as it moves westward or west-northwestward at 10 to 15 kt. Please refer to the latest NHC Tropical Weather Outlook at website: https://www.nhc.noaa.gov/text/MIATWOEP.shtml for more details on these systems. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10.5N75W to 07N81W to 1007 mb low pressure near 09.5N111.5W to 06N130W to beyond 10N140W. Other than the convection described above with three tropical waves, scattered moderate isolated strong convection is noted from 05N to 14.5N between 87W and 107W, and from 03N to 10N between 117W and 136W. Scattered moderate convection is noted from 08N to 17N between 136W and 140W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 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, and for related convection. A modest pressure gradient continues across the Gulf of Tehuantepec area, where the northern portion of a tropical wave has just passed by, and is producing strong N to NE gap winds in the Gulf and downstream to near 14N96W. Seas are 5 to 8 ft across the area. Across the remainder of the offshore waters of Mexico, typical ridging has been disrupted by a surface trough from Baja California Norte to the southwest resulting in a rather weak pressure gradient across the region, and mainly light to gentle N to NE winds, except moderate from near Cabo Corrientes up the coast toward the entrance of the Gulf of California. Seas are 4 to 6 ft across the waters away from the Gulf of Tehuantepec, and 1 to 3 ft inside the Gulf of California. An upper level trough extending offshore of SW Mexico continues to support clusters of strong thunderstorms along the coasts and nearshore waters of western Guerrero and Michoacan, and continue to shift gradually westward. For the forecast, northerly gap winds will continue to pulse to strong north winds over the Gulf of Tehuantepec during the overnight into the early morning hours through the next several days, with seas occasionally building to rough. Low pressure across Baja California has shifted eastward to along the coast of mainland Mexico, and will sustain NW to W gap winds across much of the Gulf of California waters through Fri night before southerly wind flow returns. High pressure will begin to build back modestly across the Baja offshore waters Fri afternoon through Sat night to produce a more typical moderate to fresh NW wind flow there. Looking ahead, winds and seas are expected to build across the outer offshore waters of southwestern Mexico by tonight into early next week in association with a developing area of low pressure moving by just outside of the offshore waters. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Refer to the Tropical Waves section above for details on any convection. Recent satellite scatterometer data shows fresh to strong NE to E gap extending across the papagayo region to near 90W, where seas are 6 to 8 ft. Fresh easterly winds then continue downstream, and S of 12.5N, across the outer offshore waters of El Salvador and Guatemala, where seas are 6 to 7 ft. Mainly moderate or weaker winds are found elsewhere, locally fresh near the border of Peru and Ecuador close to the entrance to the Gulf of Guayaquil. Seas are 4 to 7 ft across the remainder of the waters north of 03N, and 6 to 8 ft south of 03N. Clusters of strong thunderstorms are over the waters along and south of Panama to offshore Costa Rica, due to the passing tropical wave there, described above. For the forecast, high pressure will persist over the eastern Gulf of America and northwestern Caribbean into early next week, leading to fresh NE to E gap winds pulsing to strong winds over the Papagayo region each evening and night. Moderate to fresh winds extending well downwind of Papagayo will impact the outer waters offshore of El Salvador and Guatemala through at least early next week. South of the monsoon trough, winds will gradually diminish and remain light to gentle through the weekend. Mainly moderate seas will prevail away from the Gulf of Papagayo area through the next several days. Southeasterly swell producing rough seas across the southern waters will subside today through Fri. ...REMAINDER OF THE AREA... Please see the Special Features section and the Tropical Waves section above for information on systems that have the potential for tropical cyclone formation, and any associated convection currently present leading to locally higher winds and seas. High pressure across the NE Pacific extends a ridge south- southeastward into the regional waters to offshore of Baja Surf. Fresh to strong easterly winds and 8 to 10 ft seas associated with newly named Tropical Depression Two-C in the Central Pacific basin are impacting the waters from 12N to 19N between 137W and 140W. Moderate to locally fresh trades are found elsewhere from 14N to 23N between 128W and 140W. Moderate to locally fresh winds are found south of 06N to the east of 120W and south of 02N to the west of 120W. Rough seas over the southern waters are gradually subsiding, now over the waters south of 03N, up to 9 ft south of the Equator and east of 110W. For the forecast, regardless of tropical development, the features described above will bring some increasing winds and seas to area waters south of 25N, as they move south of the current ridge in place. Away from these features, little change is expected in marine weather through the next several days, except for the rough seas over the southern waters which are forecast to fully subside by the start of the weekend.