000 AXPZ20 KNHC 240901 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Thu Dec 24 2020 Tropical Weather Discussion for the eastern Pacific Ocean from the Equator to 32N, east of 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 0900 UTC. ...SPECIAL FEATURES... Gulf of Tehunatepec Storm Warning: A strong cold front will move across the Gulf of Mexico today and tonight, followed a large area of high pressure. Northerly winds in the Tehuantepec region will increase this afternoon rapidly reaching gale force by this evening, and then reaching storm force tonight into early Fri. Gale conditions are then forecast to persist for the rest of Fri into early Sat before diminishing. Large seas of 20-24 ft are possible by early Fri while a large plume of seas of 8 ft or greater will extend well SW-W of the Tehuantepec region from this event. Marine interests transiting across or in the vicinity of the Gulf of Tehuantepec should be aware of this upcoming gap wind event, and take necessary action to avoid hazardous marine conditions over the affected waters. Please read the latest NWS High Seas Forecast issued by the National Hurricane Center at website: https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 08N78W to 09N85W to 07N91W. Segments of the ITCZ extend from 07N91W to 07N118W, and from 07N123W to 08N140W. Scattered moderate convection is noted from 07N to 11N between 113W and 123W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See Special Features for details about an upcoming Gulf of Tehuantepec storm force gap wind event. Gulf of California: A recent scatterometer satellite pass indicated strong NW winds over the northern Gulf of California, and mainly fresh NW winds elsewhere north of 26N. These winds are increasing as as high pressure builds north of the area over the Great Basin of United States. These winds are forecast to spread southward beyond the entrance of the Gulf and through Baja California Sur passages by late today, when seas are forecast to briefly reach 9 ft. Winds will diminish by late Sat as the high pressure north of the area weakens and shifts east. Looking ahead, strong NW winds may again impact the northern Gulf of California by Mon night as a cold front moves into the region. Mainly gentle to moderate NW-N winds will prevail across the offshore waters of Baja California through Fri. Winds will increase to moderate to fresh mainly north of Cabo San Lazaro toward the upcoming weekend as the pressure gradient tightens between a ridge west of the region and a trough over the Gulf of California. Large NW swell will propagate into the waters W of Baja California Sat night through Sun night with seas building to 8-12 ft. Looking ahead, fresh to strong NW winds will accompany a cold moving through the area. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Fresh to strong NE-E winds will pulse across the Papagayo region the next several days as high pressure remains in place over the W Caribbean. Swell generated during a strong upcoming Gulf of Tehuantepec gap wind event is expected to affect the offshore waters of Guatemala and El Salvador late tonight through Sat. Seas will build up to 14-19 ft, especially tonight and Fri. Otherwise, gentle to moderate winds will prevail on either side of the monsoon trough, except occasionally fresh near the Gulf of Panama. REMAINDER OF THE AREA... High pressure north of the area dominates the forecast waters north of 20N. The pressure gradient between this area of high pressure and lower pressure in the vicinity of the ITCZ is supporting fresh winds north of the ITCZ between 125W and 135W, with mostly moderate trades elsewhere N of the ITCZ to 20N. Seas are 6 to 9 ft across the trade wind belt, highest near the strongest winds. A recent scatterometer satellite pass indicated a broad surface trough or low pressure area may be starting to form along and north of the ITCZ near 120W. This is related to a large divergent area aloft, between an upper anticyclone to the east and sharp upper trough to the west. This pattern may enhance trade winds today between the surface trough or low and the high pressure north of the area. The high pressure north of 20N will weaken ahead of a cold front expected to move eastward across the waters north of 20N by tonight. Fresh to strong SW winds are expected ahead of the front tonight. Fresh to strong northerly winds and very rough seas will follow the front. By Fri night, the front is forecast to extend from 30N126W to 24N140W, then will gradually weaken and dissipate through the weekend. A reinforcing front may clip the waters north of 25N and east of 130W by the end of the weekend. Seas are forecast to peak around 12 to 14 ft behind the first front along 30N by Fri night into early Sat. Looking ahead, strong high pressure following this reinforcing front may support fresh to strong NE to E winds from 20N to 25N west of 135W Sun and Mon, with seas up to 12 ft in a mix of wind waves and longer period NW swell. $$ Christensen