000 AXPZ20 KNHC 141612 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 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 1200 UTC surface analysis and satellite imagery through 1530 UTC. ...SPECIAL FEATURES... Tehuantepec Gale Warning: An expansive 1041 mb high pressure system over the eastern United States continues to force gale-force gap winds over the Gulf of Tehuantepec. The fresh to strong winds extend south to near 10N100W. Peak seas are around 12 ft. The 8 ft seas extend west- southwestward to 07N108W. The gale- force winds will end tonight into early Fri morning as the pressure gradient from the high pressure gets disrupted with a low pressure developing in the Gulf of Mexico. Seas will subside below 12 ft later today and into tonight. Strong winds are expected to continue into the weekend. NW Eastern Pacific Gale Warning: A 1009 mb low pressure is analyzed at 33N140W with a cold front extending southwest of it to the west of the forecast waters. This low is forecast to deepen over the next few days as it gradually moves northward. Strong to gale S-SW winds are expected ahead of the cold front. After the front reaches the NW corner tonight, near gale to gale winds are expected ahead and behind the front through Fri night. Expect these winds to occur N 26N and W of 125W. Very large NW swell will be accompanying this system with seas over 20 ft beginning Fri and continuing through Sun. The 12 ft seas will expand across the Pacific waters through the weekend, extending as far south as 16N and as far east as 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 Panama near 07N78W to 07N93W to 04N108W. The ITCZ continues from 04N108W to 07N114W then from 08N124W to beyond 08N140W. A pair of lows are between the ITCZ with a 1009 mb low near 08N116W and a 1008 mb low near 08N122W. Scattered moderate convection is noted from 02N to 08N between 77W and 113W and from 04N to 10N between 121W and 138W. ...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 dominates the Mexican offshore waters, outside of the Gulf of Tehuantepec. Moderate or weaker winds and slight to moderate seas prevail across the offshore waters. Seas across the Baja California and southern Mexico offshore waters range 4 to 5 ft within mixed swell. Seas are to 2 ft in the Gulf of California. No significant convection is noted at this time. For the forecast, ridging will build over the Great Basin in the western United States late this week. This will sustain fresh to strong NW winds over the Gulf of California tonight through Fri night or early 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 to possibly very rough seas can be expected with these winds. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... An expansive and strong ridge is centered over the eastern United States. This feature and lower pressures in the deep tropics sustain persistent fresh to strong easterly trade winds across the Gulf of Papagayo region, including the coast of southern Nicaragua. Wave heights in these waters range from 6 to 9 ft. In addition, seas to 10 ft generated by the Gulf of Tehuantepec gap wind event continue to impact the offshore waters of Guatemala and El Salvador. The aforementioned strong pressure gradient is also supporting moderate to fresh northerly winds in the Gulf of Panama, extending south to 05N. Seas in these waters are 3-5 ft. Farther south, moderate southerly winds are occurring south of 03N. Seas in these waters are 4-7 in mixed swell. Elsewhere, light to gentle winds and slight to moderate seas prevail. For the forecast, the strong NE-E gap winds in the Gulf of Papagayo are expected through Fri, diminishing to moderate to fresh this weekend. Winds will increase to strong speeds by Mon. The large NW swell over the Guatemala and El Salvador offshore waters will gradually diminish through tonight. Expect rough seas in this area once again 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 warning for the northwest waters of the area. A 1019 mb high pressure system is located to the west of California and dominates most of the tropical eastern Pacific. Moderate to fresh easterly easterly trade winds are prevalent from the deep tropics to 20N. Seas in these waters are 6-8 ft. Meanwhile, moderate southerly winds are found south of 03N. Seas in these waters are 6-8 ft. In the northwest corner of the forecast waters, fresh SW winds are noted ahead of a strong cold front W of the area. This system is bringing NW swell to the area with seas ranging 8 to 11 ft. 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, merging with the aforementioned swell. $$ AReinhart