Tropical Weather Discussion

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Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Tue Dec 16 2025 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. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: The pressure gradient between the high pressure over Mexico and the eastern north Pacific monsoon trough is sustaining gale-force northerly winds across the Gulf of Tehuantepec which are forecast to diminish below gale-force in the next few hours as the high pressure will begin to shift eastward and weaken. Fresh to strong winds will then persist through tonight before diminishing along with subsiding rough seas. Please read the latest High Seas issued by the National Hurricane Center at website: https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more information. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N84W to 03N92W to 08N121W. The ITCZ continues from that point to 08N130W to beyond 04.5N140W. Scattered moderate convection is noted from 06.5N to 08.5N between 85W and 91W, from 09N to 12.5N between 92W and 102.5W, and from 06N to 14N between 103W and 136W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A Gale Warning is in effect for the Gulf of Tehuantepec. Please see the Special Feature section for more details. A 1026 mb high center is analyzed just N of the area near 32N130W. Its associated ridge extends to near the Revillagigedo Islands. The related pressure gradient is allowing for gentle to moderate northwest to north winds and slight to moderate seas over the Mexican offshore waters N of 20N. Light and variable winds and slight seas prevail elsewhere from 13N to 20N outside of the Tehuantepec area. For the forecast, gale-force winds over the Gulf of Tehuantepec will diminish by the afternoon. Elsewhere, gentle to moderate winds and moderate seas will prevail through the middle of the week. Fresh to strong northerly winds and rough seas will develop mainly just beyond the offshore waters of Baja California Norte by the middle part of the week. Moderate to fresh winds will pulse near Cabo Corrientes during the middle of the week. Fresh to at least strong gap winds and rough seas may return in the Gulf of Tehuantepec by the end of the week into next weekend. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to strong northeast winds prevail in the Gulf of Papagayo region as high pressure builds in N of the Caribbean with lower pressures along the monsoon trough over southern Costa Rica and Panama. Light to gentle winds and moderate seas are elsewhere N of 07N. S of 07N, gentle to moderate southerly winds and moderate seas prevail, except slight seas nearshore Colombia and eastern Panama. For the forecast, building high pressure N of the Caribbean and lower pressures near the monsoon trough will continue to support pulsing fresh to strong easterly trade winds and moderate seas across the Gulf of Papagayo through midweek, possibly returning Fri night into next weekend. Rough seas in the far offshore waters of Guatemala will persist through today due to a diminishing Gulf of Tehuantepec gale-force gap event. Moderate to fresh northerly winds will pulse in the Gulf of Panama this week. Gentle to moderate winds and slight to moderate seas will prevail elsewhere. ...REMAINDER OF THE AREA... A 1026 mb high center is analyzed just N of the area near 32N130W. Its associated ridge extends to near the Revillagigedo Islands. The pressure gradient between the high and relatively lower pressures near the ITCZ/Monsoon Trough is bringing moderate to fresh trade winds from 08N to 21N and W of 120W or so, locally strong between 127W and 140W from 10N to 20N. Rough seas prevail over these waters in mixed long period swell along with shorter period wind generated seas. Moderate southerly winds and moderate seas are occurring S of the monsoon trough and ITCZ. Mainly gentle to moderate winds and moderate seas prevail across the remainder of the open waters, except locally rough seas near 30N140W. For the forecast, high pressure will build further over the northern waters into the middle portion of the week leading to a tightening of the pressure gradient that will cause fresh to strong easterly winds and rough seas over much of the tradewind belt west of 120W. Over the eastern part of the area, fresh to strong easterly winds and rough seas associated with the diminishing gale-force gap wind event in the Gulf of Tehuantepec will spread westward to near 106W from 08N to 12N through today. Seas to rough near 30N140W in W-NW swell will persist through tonight. Meanwhile, a tight pressure gradient will develop offshore southern California leading to fresh to strong winds and rough seas in the N-central waters mid-week. Marine conditions should improve overall during the upcoming weekend as the pressure gradient slackens.