Tropical Weather Discussion

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Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Sun Dec 28 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: Strong high pressure over the southern United States and eastern Mexico in the wake of an upcoming Gulf of America cold front will result in a tight pressure gradient. This will induce gale-force winds north winds into the Gulf of Tehuantepec region beginning on Mon night. These winds may peak to 45 kt going into the middle part of the week. Brief gusts to storm force cannot be ruled out Tue night. Seas with these winds are expected to rapidly build to the range of 11 to 18 ft. Mariners transiting through the Gulf of Tehuantepec during this time are urged to take the necessary action to avoid the hazardous marine conditions that will be impacting these waters. Conditions in the Tehuantepec region are forecast to begin to improve early on Thu. Developing Low Pressure/large swell: A surface trough analyzed from near 20N124W to 11N129W. This trough is paired with a vigorous and broad upper-level trough that is digging southward producing a large area of scattered to numerous showers and thunderstorms from 12N to 28N between 112W and 132W. This area is also merging with a large NW swell that has been spreading across the basin, with rough to very rough seas noted N of 18N and W of 112W. An overnight scatterometer satellite data pass indicated that strong to near gale-force winds are occurring with the strongest convection. Global models suggest that a low pressure will develop in association with this trough across the waters south of about 22N between 120W and 128W today into early next week. The interaction between this feature and strong high pressure building into the region is expected to result in a rather broad zone of increasing winds reaching to strong speeds roughly from 16N to 26.5N and west of the Revillagigedo Islands, accompanied by numerous areas of moderate to heavy rain along with embedded scattered showers and isolated thunderstorms. There is a possibility that these winds may attain gale-force speeds, especially in the showers and thunderstorms. Rough to very rough seas will spread over much of the basin north of 10N and west of 115W. Seas may reach up to 15 ft with the strongest winds. 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 08N85W to 08N100W, where it transitions to the ITCZ to 10N123W to 10N140W. Scattered moderate convection is noted N of 08N between 112W and 132W. This area is also associated with a surface trough, analyzed from 20N124W to 11N129W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section for details on a gale warning that is in effect for the Gulf of Tehuantepec. Strong high pressure of 1033 mb is located well north of the area near 43N131W. A ridge axis extends from the high southward to near 20N and west of the Revillagigedo Islands. Its related gradient is allowing for fresh north to northeast winds to exist across the offshore waters of Baja California. A decaying northwest swell is providing for rough seas offshore Baja California, except for moderate seas south of Cabo San Lucas. Moderate to fresh northwest winds and slight to moderate seas are found in the Gulf of California, while moderate north winds and moderate seas are in the Gulf of Tehuantepec region. Elsewhere, moderate or weaker winds and slight to moderate seas prevail. For the forecast, NW swell propagating through the offshore waters of the Baja California peninsula will gradually subside through early Mon. Fresh to strong northwest winds are expected to develop in the Gulf of California tonight and continue into Tue night as high pressure strengthens across the region. Gentle to moderate north winds in the Gulf of Tehuantepec region will become fresh north winds early on Mon. A strong cold front will move across the Gulf of America Mon into Tue. High pressure building in behind the front will support the next gap wind event in the Gulf of Tehuantepec. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... High pressure centered over the eastern Gulf of America has an associated broad ridge that stretches southwestward toward Central America. The gradient between the ridge and lower pressure to its south is allowing for fresh to strong northeast to east winds to exits in the Gulf of Papagayo region along with moderate seas. Weak low pressure off Colombia is producing scattered showers and thunderstorms south of the Gulf of Panama from 05N to 07.5N between the coast of Colombia and 80W. Elsewhere, moderate or weaker winds and moderate seas prevail. For the forecast, the aforementioned high pressure will continue to support pulsing fresh to strong easterly trade winds in the Gulf of Papagayo through the forecast period. Gentle to moderate northerly winds are expected in the Gulf of Panama through the period, pulsing to fresh at night at times. Gentle or lighter winds and slight to moderate seas are expected elsewhere through the period. ...REMAINDER OF THE AREA... Please read the Special Features section for details on low pres/significant swell over the waters central portion of the area. Broad surface ridging associated to strong high pressure that is centered well north of the area reaches southward into the area to near 20N. A trough is analyzed from 20N124W to 11N129W. The gradient between the ridge and lower pressure in the tropics is allowing for moderate to fresh trade winds north of about 10N and west of 120W. Elsewhere, moderate or weaker winds and moderate seas are prevalent. For the forecast, the slowly decaying northwest swell is forecast to maintain that trend through early Mon as high pressure builds into the regional waters. The aforementioned trough will serve as the seedling for the development of a broad low today, perhaps near 18N125W. The tight pressure gradient between the subtropical ridge and the low pressure will sustain a large area of strong to near gale-force winds and rough to very rough seas, across most of the forecast waters north of about 15N and west of 117W into the early part of the week. Winds may reach gales at times, more likely in scattered showers and thunderstorm, but with some possibility of winds become sustained at gale-force speeds in the tight gradient north of the low. Conditions are forecast to improve by the middle of the week. A cold front will move across the NW waters late next week, followed by fresh to strong NW winds and rough to very rough seas.