Eastern Pacific Tropical Weather Discussion
287 AXPZ20 KNHC 192050 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Aug 19 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 1800 UTC surface analysis and satellite imagery through 2000 UTC. ...SPECIAL FEATURE... The axis of a tropical wave is along 138W-139W, from 17N southward, moving westward at around 15 kt. 1007 mb low pressure is analyzed near the wave at 10N139W, and has been designated Invest EP90. Numerous moderate to strong convection is noted from 08N to 15.5N between 132W and 143W. Scattered moderate convection is elsewhere south of the system from 00N to 05.5N between 137W and 148W. Recent satellite scatterometer data shows N to NE winds of 25 to 30 kt occurring in thunderstorms to the west of the low pressure center. This area of active convection is showing some signs of improved organization. Environmental conditions appear favorable for further development of this system, and a tropical depression is likely to form during the next day or so as the system moves westward to west- northwestward at 10 to 15 mph and crosses into the Central Pacific. This system has a high chance of tropical formation in the next 48 hours. Interests in the Hawaiian Islands should closely monitor the progress of this system. ...TROPICAL WAVES... The axis of a tropical wave is near 93W-94W from 03N northward to coastal sections of SE Mexico, moving westward at around 15 kt. Scattered to locally numerous moderate isolated strong convection is noted from 05N to 15.5N between 89W and 100W. An area of low pressure is forecast to form several hundred nautical miles south-southwest 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 generally west-northwestward, remaining well offshore of Mexico. This system has a low chance of tropical development in the next 48 hours. The axis of a tropical wave is near 109W south of 17N, moving westward at 10 kt. Scattered moderate isolated strong convection is noted from 07N to 15N between 101W and 113W. The axis of a tropical wave is near 138W-139W, and is described above in the special features section. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N75W to 08N91W to 09.5N108W to 07N128W to low pressure 1007 mb, Invest EP90, near 10N138W to beyond 09.5N140W. Other than the convection described above with three tropical waves, scattered moderate convection is noted from 03N to 08.5N E of 89W. Scattered moderate isolated strong convection is noted from 03N to 13N between 113W and 131W. ...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. High pressure across the NE Pacific extends a ridge south- southeastward into the regional waters to just northwest of the Revillagigedo Islands. The pressure gradient between this ridge and low pressure troughing across Baja California has relaxed today, and is yielding gentle to moderate NW to N winds across the near and offshore of Baja California north of Punta Eugenia, with fresh S to SE winds in the northern Gulf of California. Meanwhile, a tight pressure gradient continues over the Gulf of Tehuantepec ahead of an approaching tropical wave, and is producing strong N to NE gap winds in the Gulf and extending downstream to near 13.5N.596W. Resultant seas of 6 to 8 ft are present there. Winds are moderate or weaker across the remainder of the waters between Tehuantepec and Baja Sur. Seas are 4 to 6 ft across the remainder of these offshore waters, 1 to 3 ft inside the Gulf of California, except 4 to 6 ft in northern Gulf where the fresh winds are occurring. Scattered showers and isolated thunderstorms aloft are occurring over the central Gulf of California and across portions of Baja Sur, associated with another upper level low center shifting southwestward into the area. Scattered strong thunderstorms are drifting northwestward to near the coast of Tehuantepec and Oaxaca, as this convection interacts with an upper level trough across that area. For the forecast, northerly gap winds will continue to pulse to strong north winds over the Gulf of Tehuantepec each evening and night through the weekend, except likely only reaching fresh speeds Thu night. Seas will occasionally build to rough during periods of strong winds. Low pressure across Baja California will sustain a southerly wind flow across the Gulf of California waters, with fresh winds expected across northern portions there gradually diminishing this evening through Fri. Winds and seas will diminish modestly across the Baja offshore waters through the end of the week as high pressure weakens. Looking ahead, winds and seas are expected to build across the outer offshore waters of southwestern Mexico by Fri into the upcoming weekend in association with a developing area of low pressure, expected to develop 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. Fresh to locally strong easterly gap winds continue across the Papagayo region as shown by recent satellite scatterometer data, and extend downwind to near 95W. Seas there are 6 to 8 ft with these winds. Winds are moderate or weaker elsewhere north of the monsoon trough, and moderate south of the monsoon trough, except moderate to fresh south of 05N, highest near the entrance of the Gulf of Guayaquil. Seas across most of the remainder of the waters north of the Equator are 4 to 6 ft in mixed cross equatorial S and SW swell, and 7 to 9 ft in S to SW swell south of 03.5N, highest south through southwest of the Galapagos Islands. For the forecast, the pressure gradient between high pressure over the northwestern Caribbean and relatively lower pressure over Central America will lead to fresh NE to E gap winds pulsing to strong winds over the Papagayo region each evening and night through the rest of the week and into the weekend, resulting in rough seas at times. Moderate to fresh winds extending well downwind of Papagayo will impact the outer waters offshore of El Salvador and Guatemala through the upcoming weekend. Moderate to locally fresh southerly winds south of the monsoon trough and across the Galapagos waters will gradually diminish tonight through Thu than remain gentle to moderate through the weekend. Cross- equatorial SW swell moving into the regional waters will continue to merge with larger S to SE swell dominating the southern Pacific waters well south of the Galapagos to produce rough seas 8 ft and greater south of 02N, and moderate seas elsewhere through Thu before the rough seas area subsides. ...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. High pressure across the NE Pacific extends a ridge south- southeastward into the regional waters to just northwest of the Revillagigedo Islands. Moderate to locally fresh NE to E winds are noted from around 09N to 21N between 120W and 140W. Seas are 5 to 8 ft across these waters with a tropical wave helping to enhance conditions there. Moderate to fresh SE to S winds are found south of 05N, with winds mainly moderate or weaker across the remainder of the waters. Seas are 7 to 10 ft south of 04N in mixed cross equatorial swell, and mainly 5 to 7 ft across the remainder of the waters, slightly lower in the north- central waters right under the ridging. Numerous moderate to strong convection from 08N to 15.5N between 132W and 143W accompanies the tropical wave along 138W-139W. For the forecast, regardless of tropical development, the tropical waves described above will bring some increasing winds and seas to area waters S of 20N, as they move south of the current ridge in place. Expect active thunderstorms and potential for winds to 30 kt with gusts in excess of 35 kt near the tropicalwave along 138W-139W this evening and tonight. Away from these tropical waves, little change is expected in marine weather through the week and into the upcoming weekend.