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Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Mon Dec 29 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 next gap wind event across the Tehuantepec region will begin this afternoon as a ridge builds across the eastern slopes of the Sierra Madre Mountains in Mexico, behind a strong cold front moving across the Gulf of America. Winds are expected to suddenly increase to 35 to 40 kt, with seas building to 9 to 12 ft by tonight. On Tue, winds are forecast to increase to near storm force, with seas building up to 17 or 18 ft. Fresh to strong winds and large seas generated by this event will spread well away from the Tehuantepec area, with seas 8 ft or greater reaching as far west as 105W by Tue evening. Marine interests transiting across or in the Gulf of Tehuantepec later today through Tue night should be aware of this upcoming gap wind event, and take the necessary action to avoid this hazardous marine conditions over the affected waters. Gale conditions are forecast to continue through Wed night. Conditions in the Tehuantepec region are forecast to begin to improve on Thu. Developing Low Pressure/Swell event: A surface trough is analyzed from 22N125W to13N127W. This trough is paired with a vigorous and broad upper-level trough that is digging southward producing abundant cloudiness with scattered to numerous showers and thunderstorms, particularly from 15N to 20N between 115W and 120W. This area is also merging with a large NW to N swell that has been spreading across the basin, with rough seas noted from 05N to 27N west of 115W. Earlier scatterometer satellite data confirmed that fresh to strong winds are occurring between the trough and high pressure to the north. The strongest winds to 25 kt are noted from 18N to 23N between 118W and 133W. Seas of 8 to 12 ft are within these winds. A broad low pressure area is expected to develop in association with this trough near 20N127W by this evening. The low is forecast to move northward and north of the area by Wed evening or Wed night. The interaction between this feature and high pressure to the north will continue to result in a broad zone of fresh to strong winds from 15N to 27N and west of 120W through tonight. Seas may reach up to 14 ft with the strongest winds today. Conditions are forecast to improve by the middle of the week. Please read the latest High Seas Forecast 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 10N85W to 08N95W to 10N100W. The ITCZ continues from 10N100W to 13N120W to 07N140W. Numerous moderate to isolated strong convection from 15N to 20N between 115W and 120W. Scattered moderate convection from 20N to 22N between 125W and 128W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A gale warning is in effect for the Gulf of Tehuantepec. Please refer to the Special Features section for more details. High pressure of 1032 mb is located well north of the area near 38N133W. A ridge axis extends from the high across the offshore forecast waters of Baja California supporting moderate to fresh north to northeast winds with moderate seas. Fresh to strong NW winds and slight to moderate seas are found in the Gulf of California, while light winds and slight seas are in the Gulf of Tehuantepec. Elsewhere, moderate or weaker winds and slight to moderate seas prevail. For the forecast, the next gap wind event in the Tehuantepec region will begin today. See the Special Features section for more details. Fresh to strong northwest winds and building seas will prevail across most of the Gulf of California through Tue night as high pressure persists over the SW of the United States. Elsewhere, moderate or weaker winds and slight to moderate seas are expected. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... 1030 mb high pressure is centered north of the area near 39N132W. This area supports fresh to strong northeast to east winds in the Gulf of Papagayo and downwind to near 87W as noted in a recent scatterometer pass. Seas of 4 to 5 ft are within these winds based on altimeter data. Weak low pressure of 1010 mb located off Colombia is producing scattered showers and thunderstorms in the eastern Gulf of Panama. Elsewhere, moderate or weaker winds and slight to moderate seas prevail. For the forecast, the aforementioned high pressure will continue to support pulsing fresh to strong NE to E winds in the Gulf of Papagayo with moderate to rough seas through the forecast period. Gentle to locally moderate northerly winds are expected in the Gulf of Panama through Fri. Seas generated by strong winds in the Tehuantepec region will propagate across the offshore forecast waters of Guatemala and El Salvador Tue through Wed night. Light to gentle winds and slight to moderate seas are expected elsewhere through this work-week. ...REMAINDER OF THE AREA... Please read the Special Features section for details on a developing low pres and a significant swell event over the central waters of the forecast region. Broad surface ridge associated to a 1032 mb high pressure located N of area near 38N133W dominates mainly the area N of 20N and W of 120W. The pressure gradient between the high and the above mentioned surface trough is allowing for a large area of fresh to strong NE winds from 16N to 27N W of 120W. Seas of 8 to 12 ft are noted within these winds based on altimeter data. Elsewhere, moderate or weaker winds and moderate seas are prevalent. For the forecast, outside of the developing low pressure and the swell event, a cold front is forecast to reach the NW waters Wed night into Thu. A reinforcing front will also reach the same area later on Thu, merging with the main front by Thu evening. Fresh to strong winds are expected on either side of the front. A new swell event will follow the front bringing rough to very roughly seas.