000 AXPZ20 KNHC 130936 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 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 0600 UTC surface analysis and satellite imagery through 0855 UTC. ...SPECIAL FEATURES... Tehuantepec Gale Warning: A 1026 mb high pressure system over NE Mexico is forcing gale-force gap winds over the Gulf of Tehuantepec. Peak seas are around 16 ft. A recent altimeter satellite pass captured seas near 15 ft just east of the analyzed peak. 8 ft seas extend west-southwestward to 09N110W. These northerly gap winds will gradually diminish with gale conditions ending Thu night. Strong winds will persist through the end of the week. 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 130W 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 127W 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 Panama near 08N81W to 06N93W. The ITCZ stretches from 06N93W to 08N115W to beyond 06N140W. Scattered moderate convection is noted from 04N to 08N and between 90W and 105W. Scattered moderate to isolated strong convection is observed from 05N to 14N and between 107W and 130W. ...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 sustain moderate NW winds in the offshore waters of Baja California Norte. Seas in these waters are 4-6 ft. In the remainder of the Mexican offshore waters, outside of the Gulf of Tehuantepec, light to gentle variable winds and slight to moderate seas are prevalent. For the forecast, high pressure will build over the U.S. Great Basin late this week resulting 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. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A strong pressure gradient resulting from a 1035 mb high pressure system over the SE United States and lower pressures in the deep tropics continue to sustain fresh to strong NE-E gap winds across the Gulf of Papagayo region. This was confirmed by a recent scatterometer satellite pass. Seas in these waters are 7-10 ft. Northerly swell producing seas of 8-10 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. 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 today and 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... A 1020 mb high pressure system centered near 31N133W extends weakly southeastward to the Revillagigedo Islands. A recent scatterometer satellite pass depicted moderate to fresh easterly trade winds south of 20N and north of the ITCZ. 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 03N and westward to 110W. 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, a large extratropical low will approach the NW corner of our waters late Thu with strong to gale S-SW winds 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 west of 130W 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 127W. The remainder of the waters will have winds moderate or weaker and moderate seas. $$ Delgado