010 AXPZ20 KNHC 142156 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 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 1800 UTC surface analysis and satellite imagery through 2130 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 09N97W. 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 tonight into early Fri morning. Strong winds will continue into the weekend, with gale force winds returning by Sat afternoon. This next round of gale force winds will persist through the weekend and continue into early next week. Rough to very rough seas are expected. NW Eastern Pacific Gale Warning: A 1009 mb low pressure is analyzed at 34N138W 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. As the front reaches the NW corner tonight, near gale to gale winds are expected ahead and behind the front through Fri night. Another front will enter the forecast waters from the same extratropical low on Saturday, bringing another round of gale- force winds. Expect these winds to occur N 26N and W of 128W. The gale force winds will end by Sat night with strong winds continuing across the northwest waters through Sun. Very large NW swell will be accompanying this system with seas over 12 ft entering the waters by tonight and continuing through Mon. These seas will expand across the Pacific waters through the weekend, extending as far south as 14N and as far east as 125W. Peak seas will be well over 20 ft and expected to occur Fri through Sun. Seas will slowly subside through early next week. 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 Colombia near 06N77W to 06N94W to 05N111W. The ITCZ continues from 05N111W to 07N122W then from 08N128W to beyond 10N140W. A trough extends from 06N127W to 09N124W. Scattered moderate convection is noted from 02N to 09N between 82W and 113W and from 05N to 09N between 125W and 140W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section for details on a Gale Warning for the Tehuantepec region. High pressure is building over the U.S. Great Basin. This is causing moderate to locally fresh winds over the Gulf of California with seas to 4 ft. Meanwhile, 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 rest of the offshore waters. Seas across the Baja California and southern Mexico offshore waters range 4 to 6 ft within mixed swell. No significant convection is noted at this time. For the forecast, ridging will build over the Great Basin in the western United States through Sat. This will sustain fresh to strong NW winds over the Gulf of California tonight through Sat with winds subsiding through Sun. Another round of gale-force winds across the Gulf of Tehuantepec is expected to begin on 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. This is confirmed by the latest scatterometer data which depicts the fresh to strong winds extending as far west as 07N92W. Wave heights in these waters range from 6 to 8 ft. In addition, seas to 9 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 06N noted by the latest scatterometer data. Seas in these waters are 3-5 ft. Farther south, moderate southerly winds are occurring south of 03N. Seas in these waters are 4 to 5 ft 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 and continue through midweek. 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. In the northwest corner of the forecast waters, fresh SW winds are noted ahead of a strong cold front W of the area confirmed by scatterometer data. This system is bringing NW swell to the area with seas ranging 8 to 12 ft. A 1022 mb high pressure system is located to the west of California and dominates most of the tropical eastern Pacific. Moderate to fresh easterly trade winds are prevalent from the ITCZ to 21N. 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. 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 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