Tropical Weather Discussion

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Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Tue Dec 9 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 1430 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: The pressure gradient between high pressure over the eastern slopes of Mexico and lower pressure within the eastern north Pacific monsoon trough is supporting gale- force gap winds in the Gulf of Tehuantepec, with peak winds likely around 40 kt. Gale- force winds will likely persist through much of tonight. Very rough seas, peaking around 12 or 13 ft, are expected with this event through early today. Please read the latest High Seas issued by the National Hurricane Center at website: https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml 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. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09.5N84W to 06N101W to 12N114W to 09N130W. The ITCZ continues from 09N130W to 07N140W. Scattered moderate and isolated strong convection is noted from 10N to 18N between 110W and 123W. Scattered moderate convection is noted from 06N to 10N between 130W and 140W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A Gale Warning is in effect for the Gulf of Tehunatepec. Please see the Special Features section for more information. Aside from conditions in the Gulf of Tehuantepec, a ridge extends from high pressure located N of the area to across the offshore forecast waters of Baja California. The pressure gradient between this ridge and a trough over western Mexico is supporting fresh to locally strong winds over the Gulf of California. Gentle to moderate winds are over the waters west of the Baja California peninsula extending southward to the Revillagigedo Islands. Light to gentle winds and moderate seas in long period NW swell are noted across the remainder of the Mexican offshore waters. For the forecast, gale-force northerly gap winds in the Gulf of Tehuantepec will peak around 40 kt early today, with gale-force winds continuing through much of tonight. Fresh N winds may develop near Cabo Corrientes tonight through Wed night. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to fresh winds are in the Gulf of Papagayo, with light to gentle winds elsewhere N of 05N. Gentle to locally moderate southerly winds prevail S of 05N. Seas are mainly moderate in mixed SW and NW swell, with exception of slight seas nearshore from Colombia northward. For the forecast, mainly gentle winds will prevail N of the monsoon trough over the next several days, except pulsing to moderate to fresh in the Gulf of Papagayo, locally strong at times. Gentle to moderate winds will prevail S of monsoon trough. Moderate N winds will pulse in the Gulf of Panama starting tonight. Seas generated by a gale-force gap wind event in the Gulf of Tehuantepec are expected to spread across the outer offshore waters of El Salvador and Guatemala today and tonight. Otherwise, moderate seas in mixed SW and NW swell are expected over the regional waters through the week and into next weekend. ...REMAINDER OF THE AREA... High pressure dominates the waters N of the ITCZ and monsoon trough. A surface trough is analyzed from 18N110.5W to 11N114W. The pressure gradient between this area of high pressure and lower pressure in the vicinity of the ITCZ and within the monsoon trough is supporting moderate to fresh winds north of the monsoon trough/ITCZ and west of 110W. Seas are in the 5-9 ft range over these waters, highest S of 20N and W of 120W. Moderate winds, and seas of 4 to 7 ft, prevail elsewhere over the discussion waters. For the forecast, little change to the synoptic pattern and marine conditions are expected through the middle of the week, with winds weakening somewhat later in the week as the pressure gradient weakens. A new set of long period NW swell is forecast to reach the NW part of the forecast region by Wed evening, building seas to 8 to 9 ft over these waters before subsiding by the end of the week.