Tropical Weather Discussion

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Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Gale warning near 20N127W/swell event: 1007 mb surface low pressure is centered near 20N127W. This is associated with a broad upper level cyclone over the same area. Numerous moderate to isolated strong convection is ongoing within 90 nm to the northeast of the center of the low pressure. A recent scatterometer satellite pass indicated winds to 35 kt were already ongoing within 120 nm to the north of the center of the low pressure. Based on recent data from a nearby altimeter satellite pass, combined seas are estimated to be 12 to 14 ft in the area of near-gale and gale force winds, specifically from 19N to 23N between 120W and 132W. In addition, scattered moderate convection is active east of the low pressure along a trough from 20N115W to 15N118W, where the recent scatterometer pass showed strong to near-gale force winds outside of the areas of thunderstorms. Winds and seas will likely subside through the late evening as the main energy associated with low pressure complex weakens and shifts to the north of the area. Gulf of Tehuantepec Gale Warning: 1037 mb high pressure is building over west Texas this afternoon, following a strong cold front moving through the Gulf of America. This is supporting increasing gap winds across the isthmus of Tehuantepec in southern Mexico, and winds are starting to increase across the Gulf of Tehuantepec. These gap winds are expected to increase to 35 to 40 kt, with seas building to 9 to 12 ft by this evening. 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. 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 09N105W. The ITCZ continues from 09N105W to 12N122W to 06N140W. No significant convection is active along the ITCZ or monsoon trough. ...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. 1032 mb high pressure is located well north of the area near 39N133W. 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. In addition, strong 1043 mb high pressure is centered over the Great Basin. Surface troughs are noted along the coast of southern California, and over northwest Mexico. This pattern is supporting strong to near- gale force NW winds across the Gulf of California, as noted in a recent scatterometer satellite pass. Seas are likely 4 to 6 ft across the Gulf of California. The scatterometer pass also showed fresh to strong NW gap winds off Punta Eugenia, on the Pacific coast of Baja California, and near Todos Santos off Baja California Sur. Other than the developing gap winds over the Gulf of Tehuantepec discussed in the Special Features section, gentle to moderate winds and moderate wave heights primarily in NW swell are noted elsewhere. For the forecast, gap winds across the Gulf of Tehuantepec are starting to increase this afternoon in response to large high pressure building north of the area following a strong cold front moving through the Gulf of America. Winds are expected to suddenly increase to 35 to 40 kt, with seas building to 9 to 12 ft by this evening. On Tue, winds are forecast to increase to near storm force, with seas building up to 16 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. Gale conditions are forecast to continue through Wed night. Farther north, strong high pressure over the Great Basin will support fresh to strong northwest winds and building seas across most of the Gulf of California through Tue night. 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... Strong high pressure building well north of the region is supporting fresh to strong northeast to east winds in the Gulf of Papagayo and downwind to near 90W. Seas of 5 to 6 ft are within these winds based on altimeter data. 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 gale warning near 20N127W and a significant swell event over the central waters of the forecast region. In addition to the low pressure and associated weather discussed in the Special Features section, a large area of fresh to strong winds and 8 to 11 ft seas are noted from 10N to 28N west of 115W. Farther south, fresh southerly winds and rough seas are evident from 05N to 10N between 115W and 130W, flowing into the broad low farther north. Gentle to moderate winds and 5 to 7 ft seas primarily in NW swell are evident elsewhere. For the forecast, outside of the gale center and the swell event, a cold front is forecast to reach near 30N140W Wed night and move westward across the waters north of 25N 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.