Tropical Weather Discussion

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Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Mon May 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 0300 UTC. ...SPECIAL FEATURES... Northern Gulf of California Gale Warning: A trough moving across the lower Colorado River Valley associated with deep 988 mb low pressure near Las Vegas is supporting strong to gale force gap winds into the northern Gulf of California tonight. Winds will diminish through Mon as 1033 mb high pressure off southern California builds over the region in the wake of the trough. Significant Swell Event West of Baja California Norte: Very large, long-period NW swell is causing very rough seas of 12 to 16 ft, north of 27N and east of 125W, including waters near Guadalupe Island. This swell will continue to propagate southward through this evening, causing very rough seas to reach near 26N late tonight. As the NW swell gradually decays and retreats northward Mon through Mon night, seas should subside below 12 ft by late Mon night. For both events above, please refer to the latest High Seas and Offshore Waters Forecasts issued by the National Hurricane Center at websites: https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and https://www.nhc.noaa.gov/marine/offshores_eastpac.php for more details. ...TROPICAL WAVES... A tropical wave extends from the southwest Caribbean across Panama to 03N80W, moving west at 5-10 kt. A few showers and thunderstorms are active over Panama, mostly related to sea breeze influences. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A monsoon trough extends from 10N85W to 06N95W. The monsoon trough extends from 06N95W to 05N140W. Scattered moderate convection is active from 08N to 12N between 90W and 95W, and from 07N to 10N between 128W to 140W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please read the Special Features section above regarding a Gale Warning and Significant NW swell. In addition the gale force winds mentioned in the Special Features section, the pattern is supporting fresh NW winds off Baja California Norte, coincident with the large NW swell. Gentle to moderate breezes are noted elsewhere. Combined seas are 5-7 ft off Baja California Sur, with 4-6 ft off southern Mexico and 1-3 ft over the central and southern Gulf of California. For the forecast, the high pressure will build over the area in the wake of the trough moving through the lower Colorado River valley. Aside from the winds and seas described in the Special Features section, gentle to moderate breezes and mostly moderate seas will prevail elsewhere. ....OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A recent scatterometer satellite pass indicated fresh gap winds downwind of the Gulf of Papagayo, and north of a broad circulation along the monsoon trough centered near 09N88W. Gentle breezes and 3-5 ft seas are noted elsewhere primarily with SW swell. A few thunderstorms are active southwest of Cocos Island. For the forecast, fresh to strong winds will pulse across the Gulf of Papagayo mainly in overnight and early morning hours through Thu morning. Elsewhere, gentle to moderate winds along with moderate seas in southerly swell are expected through midweek. ...REMAINDER OF THE AREA... A broad ridge covers the waters north of 20N, anchored by 1033 mb high pressure centered near 39N138W. Fresh to strong NW to N winds and large NW swell cover the waters north of 20N and east of 130W. Fresh to strong NE to E winds and 8-9 ft seas are noted north of 10N west of 125W. Gentle to moderate breezes are noted elsewhere. Seas are 6-8 ft in S swell south of 10N and west of 120W, with 5-7 ft seas in a mix of NW and SW swell elsewhere over the tropical Pacific. For the forecast, the aforementioned ridge should gradually weaken while retreating northward starting Mon afternoon. This will allow winds and seas north of the ITCZ to steadily subside from east to west through midweek, becoming gentle to moderate winds with 6-8 ft seas by Thu. Winds south of the ITCZ will also becoming gentle by Thu with higher seas at 5-7 ft in mixed swells.