805 AXPZ20 KNHC 131557 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Wed Dec 13 2023 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 1530 UTC. ...SPECIAL FEATURES... Tehuantepec Gale Warning: Strong high pressure over the Gulf of Mexico is forcing gale- force gap winds over the Gulf of Tehuantepec. Peak seas are around 15 ft. The 8 ft seas extend west- southwestward to 07N105W. The gale force winds will end Thu night into early Fri morning. Strong winds will persist through the weekend. Seas will subside below 12 ft by Fri morning. NW Eastern Pacific Gale Warning: A weak cold front is approaching the northwest waters of the tropical eastern Pacific. A reinforcing cold front will arrive to the area on Thu, triggering the formation of a large extratropical cyclone that will approach the NW corner of our waters late Thu. Strong to gale S-SW winds are forecast ahead of its associated cold front. After the front reaches the NW corner on Thu night, near gale to gale W to NW winds behind the front should occur north of 23N and west of 123W through early Sat. Very large NW swell will be accompanying this system with seas up to near 20 ft and 12 ft seas continuing through the weekend north of 20N west of 125W Please read the latest High Seas Forecast and the Offshore Waters Forecast issued by the National Hurricane Center at https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and www.nhc.noaa.gov/marine/offshores.php for details on the special feature. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from the coast of Costa Rica near 09N84W to 06N92W. The ITCZ extends from 06N92W to 06N106W to 09N125W and then from 08N129W to beyond 07N140W. Scattered moderate isolated strong convection is noted from 04N to 13N between 90W and 128W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the SPECIAL FEATURES section for details on a Gale Warning for the Tehuantepec region. A weak pressure gradient across the Baja California offshore waters is sustaining gentle to moderate NW winds. Seas range 4 to 5 ft within NW swell. Gentle winds prevail in the Gulf of California with seas to 1 ft. In the southwest Mexico offshore waters, outside of the Gulf of Tehuantepec, light to gentle variable winds prevail with seas 4 to 6 ft within mixed E and SE swell. No significant convection is noted at this time. For the forecast, high pressure will build over the U.S. Great Basin late this week. This will result in fresh to strong NW winds over the Gulf of California starting on Thu night through Sat. Looking ahead, a new gale-force gap wind event over the Gulf of Tehuantepec is expected to begin on late Sat and continue into early next week. Rough seas can be expected with these winds. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Surface ridging from a 1037 mb high pressure system over the SE United States extends across the Gulf of Mexico and NW Caribbean Sea. This is interacting with lower pressures in the deep tropics, and the resulting pressure gradient is sustaining persistent fresh to strong NE-E gap winds across the Gulf of Papagayo region. Seas in these waters are 7-10 ft. Northerly swell producing seas of 8-11 ft generated by the Gulf of Tehuantepec gap wind event continues to affect the offshore waters of Guatemala and El Salvador. Moderate to fresh northerly winds and seas of 2-4 ft are evident in the Gulf of Panama. Meanwhile, moderate to locally fresh southerly winds are noted south of 03N. Seas in these waters are 4-6 ft in a mixed N to NW and S swell. Elsewhere, light to gentle winds and slight to moderate seas prevail. For the forecast, the strong NE winds in the Gulf of Papagayo are expected through Fri, diminishing to moderate to fresh this weekend. Peak seas will be near 10 ft Wed through Thu. The large NW swell over the Guatemala and El Salvador offshore waters will only gradually diminish through Fri and once again occur beginning on Sun. Elsewhere, winds are moderate or weaker for the next several days. ...REMAINDER OF THE AREA... Please see the Special Features section for more information on the gale warnings for the northwest waters of the area. A weakening 1018 mb high pressure system centered near 31N133W extends southeastward to the Revillagigedo Islands. Moderate to fresh easterly trade winds are noted N of the ITCZ to 21N. Seas in these waters are 5-8 ft. Large 8-10 ft NW to N swell being produced by the Gulf of Tehuantepec gap wind event extends equatorward to 05N and westward to 105W. Meanwhile, a weakening cold front is approaching the northwest corner of the basin and no deep convection is associated with this feature. Elsewhere, moderate or weaker winds and moderate seas are prevalent. For the forecast, trade winds will continue to be moderate or weaker through the weekend as the extratropical low moves across the area. Large swell from this system will impact most of the waters, with the 8 ft seas extending as far south as the equator and as far east as 110W. A new gale event across the Gulf of Tehuantepec will bring rough waters to the high seas later on Sun and into Mon, extending towards 10N101W. $$ AReinhart