000 AXPZ20 KNHC 192121 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Sun Dec 19 2021 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 2100 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A ridge building across the eastern slopes of the Sierra Madre Mountains in Mexico and over the western Gulf of Mexico will support the next gap wind event across the Tehuantepec region. Sustained winds of 25 to 30 kt are expected tonight and Mon. These winds will further increase to minimal gale force Mon night through Tue night. Then, fresh to strong northerly will continue to blow across the Tehuantepec area through Fri. Seas 8 ft or greater generated by this gap wind event will reach as far west as 12N97W. Please read the latest NWS High seas Forecast issued by the National Hurricane Center at website: https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from southern Costa Rica near 09N83W to 07N90W to 08N100W. The ITCZ begins near 09N116W to 08N132W to 07N140W. Scattered moderate convection can be found 13N-15N between 105W-109W, and from 08N-11N between 123W-126W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO A Gale Warning is in effect for the Gulf of Tehuantepec. Please, see the Special Features section for details. High pressure of 1024 mb located near 29N125W extends a ridge across the offshore forecast waters on Baja California producing mainly gentle to moderate NW to N winds. Gentle to moderate N winds are also noted between Las Maria Islands and Los Cabos, including the entrance to the Gulf of California while light to gentle winds are observed elsewhere over the open waters off Mexico, including the Tehuantepec region. High pressure over the SW CONUS supports mainly moderate NW to N winds across most of the Gulf of California. Seas are in the 4-6 ft offshore Baja California. Seas of 3-5 ft are noted elsewhere, with seas of 204 ft in the Gulf of California. For the forecast, the aforementioned high pressure will move eastward and continue to dominate the offshore forecast waters of Baja California through at least Wed. Outside of the Tehuantepec area, seas will continue to subside during the next couple of days. A cold front will approach to the northern Baja California toward the end of the work-week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR Moderate to locally fresh NE winds are observed in the Gulf of Papagayo. Light to gentle winds are noted elsewhere north of the monsoon trough while gentle to moderate S to SW winds are noted south of the monsoon trough per scatterometer data. Seas are generally 3 to 5 ft across the offshore forecast waters. For the forecast, fresh to locally strong NE to E winds will continue to pulse in the Papagayo region through the next several days, particularly during the overnight and early morning hours. Gentle to moderate winds will prevail elsewhere. No significant swell events are forecast during the next several days. REMAINDER OF THE AREA... Surface high pressure of 1024 mb centered near 29N125W dominates the waters north of 15N while a cold front has reached the NW corner of the forecast region. The pressure gradient between the high pressure and lower pressure in the vicinity of the ITCZ is supporting an area of moderate to locally fresh trade winds from 12N to 18N W of 112W. Seas W of 110W associated with the recent NW to N swell event continue subside. Seas of 8-10 ft currently dominate the waters from 07N to 15N W of 130W, and from 10N TO 15N between 121W and 130W. For the forecast, the swell event affecting mainly the waters W of 110W will continue to decay over the next 12-24 hours. The above mentioned cold front will move across the northern forecast waters reaching from 30N134W to 26N140W tonight, and from 30N133W to 25N140W by Mon morning. Fresh to strong winds are expected on either side of the front. Another set of long period NW swell will follow the front, building seas to 8-12 ft. $$ GR