000 AXPZ20 KNHC 140311 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Thu Dec 14 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 0000 UTC surface analysis and satellite imagery through 0315 UTC. ...SPECIAL FEATURES... Tehuantepec Gale Warning: A robust high pressure over eastern United States continues to force gale-force gap winds over the Gulf of Tehuantepec. The fresh to strong winds extend south to near 10N and west to 104W. Peak seas are around 15 ft. The 8 ft seas extend west- southwestward to 05N105W. 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 into early Fri. 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 25N and west of 123W through Fri night into early Sat. Very large NW swell will be accompanying this system with seas over 20 ft through Sun. The 12 ft seas will through the weekend, extending as far south as north of 18N and as far east as 129W. 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 08N78W to 06N92W. The ITCZ extends from 06N92W to 06N103W to 08N113W. A surface trough is analyzed from 12N118W to 07N125W. The ITCZ then continues from 07N129W to beyond 08N140W. Isolated to scattered moderate convection is observed within 120 nm on both sides of the ITCZ between 87W and 120W. ...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 1019 mb high pressure system extends southeastward to the Revillagigedo Islands. Moderate N-NE winds and seas of 4-6 ft are evident in the SW Mexican offshore waters, mainly from 16N to 22N and east of 116W. Outside of the Gulf of Tehuantepec, light to gentle variable winds and slight to moderate seas prevail in the rest of the Mexican offshore waters. 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 Fri night. 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 to very rough seas can be expected with these winds. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A 1041 mb high pressure system over the eastern United States and lower pressures in the deep tropics support persistent fresh to strong NE-E gap winds across the Gulf of Papagayo region. Seas in these waters are 6-9 ft. Rough seas generated by the Gulf of Tehuantepec gap wind event continues to impact the offshore waters of Guatemala and El Salvador. The aforementioned strong pressure gradient is also sustaining moderate to fresh northerly winds in the Gulf of Panama. Seas in these waters are 2-4 ft. Meanwhile, moderate southerly winds are noted south of 03N, along with seas of 4-6 ft in mixed swell. Elsewhere, light to gentle winds and slight to moderate seas prevail. For the forecast, the strong easterly winds in the Gulf of Papagayo are expected through Fri, diminishing to moderate to fresh this weekend. Peak seas will be near 9 ft tonight through Thu. The large NW swell over the Guatemala and El Salvador offshore waters will only gradually diminish through Thu night. Expect another round of rough seas in this area due to another Gulf of Tehuantepec gap wind event 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 weak subtropical ridge positioned west of California extends southward into the remainder of the tropical eastern Pacific. Moderate to fresh easterly winds and seas of 6-9 ft prevail from 05N to 22N. Meanwhile, moderate southerly winds are found south of 03N. Seas in these waters are 6-8 ft. A weakening cold front is approaching the northwest corner of the basin and no deep convection is associated with this feature. Elsewhere, light to gentle winds and moderate seas are prevalent. For the forecast, trade winds will slowly diminish to be moderate or weaker by Fri and continue through the weekend as the extratropical low moves across the area. Large swell from the extratropical low will impact most of the waters, with the 8 ft seas extending as far south as the equator and as far east as 100W. 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 10N100W. $$ Delgado