Tropical Weather Discussion

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Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Tue Dec 30 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 Storm Warning: Gale-force northerly winds are blowing across the Gulf of Tehuantepec and downwind to about 13N as high pressure builds southward the eastern slopes of the Sierra Madre Mountains in Mexico. Winds will increase to storm force this afternoon and evening, with seas building to 12 to 18 ft. Large seas generated from these gap winds will spread well away from the Tehuantepec area, with seas 8 ft or greater reaching as far west as 105W by this evening into tonight. Marine interests transiting across or near the Gulf of Tehuantepec through Wed should take the necessary action to avoid these hazardous marine conditions. Although storm conditions will end by Wed morning, gales will prevail through Wed night. Winds and seas will gradually diminish Thu and Thu night. Of note: The monthly distribution of Tehuantepec events shows that the largest number of gale force events occurs in December. Storm-force events occur most often in January. 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 06N92W. The ITCZ stretches from 06N92W to 10N109W, then continues from 09N131W to beyond 06N140W. No significant convection is associated these features at this time. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A Storm Warning is in effect for the Gulf of Tehuantepec. Please refer to the Special Features section for details. A 1025 mb high pressure is located well north of the area near 41N130W. A ridge axis extends from the high southward to W of the waters offshore Baja California, supporting gentle to moderate north to northeast winds with moderate seas, with the exception of moderate to locally fresh NE winds in the Bay of Sebastian Vizcaino. Fresh to strong NW to N winds are evident across the Gulf of California due to the presence of a strong 1043 mb high pressure over the Great Basin. Seas are 6 to 8 ft within these wind speeds. Fresh to strong N winds are also in the vicinity of San Jose del Cabo. Elsewhere, gentle to moderate winds and moderate seas in NW swell are noted. For the forecast, aside from the storm conditions over the Gulf of Tehuantepec, strong high pressure over the Great Basin will support fresh to strong northwest winds and moderate to rough seas across most of the Gulf of California through tonight. 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 north of the region is supporting fresh to strong northeast to east winds in the Gulf of Papagayo and downwind to near 88W. Seas of 5 to 7 ft are within these winds. Elsewhere, moderate or weaker winds and slight to moderate seas prevail. For the forecast, the aforementioned high pressure will continue to support fresh to strong NE to E winds in the Gulf of Papagayo with moderate to rough seas through the forecast period. The forecast calls for winds of 20 to 30 kt, mainly at night, with seas building up to 10 ft through Thu night. 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 today through Wed night. Light to gentle winds and slight to moderate seas are expected elsewhere through this work-week. ...REMAINDER OF THE AREA... A 1006 mb surface low pressure is centered near 21N127W. A surface trough extends from the low center to 16N124W to 10N128W. An area of numerous moderate to isolated strong convection is noted E of the trough axis from 12N to 21N between 110W and 123W. This is associated with a broad upper-level cyclone over the same area. Recent satellite derived wind data indicate that winds related to this low have diminished below gale force, and the Gale Warning is allowed to expired. However, a large area of fresh to strong winds remains associated with this system, and continues to dominate roughly the waters N of 16N W of 118W. Seas of 8 to 12 ft, primarily in NE swell, are noted from 14N to 27N W of 120W. As the low pressure moves northward over the next 24 to 48 hours winds and seas will gradually diminish. Elsewhere, gentle to moderate winds and 5 to 7 ft seas primarily in NW swell are evident elsewhere. For the forecast, outside of the complex low pressure system 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. At that time, the front will extend from 30N134W to 24N140W. 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.