000 AXPZ20 KNHC 151558 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Wed Dec 15 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N78.5W to 09N86W to 07N96W. The ITCZ extends from 07N96W to 08N115W, then resumes W of a surface trough from 06N125W to 06N140W. Scattered moderate convection is noted within 120 nm off the coasts of Colombia, Panama and Costa Rica. Scattered moderate convection is also noted from 05N to 08N between 85W and 94W. A surface trough extends from 10N117W to 05N124W. Scattered moderate isolated strong convection is noted from 06N to 09N between 117W and 124W, and from 12N to 15N between 113W and 118W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO A cold front extends across Sonora to the Gulf of California near 29N113W across Baja California Norte to 28N116W. Fresh to locally strong winds are in the central and northern Gulf of California associated with the front, where seas are 4-6 ft. Fresh NNW winds are west of Baja California. Altimeter data from 15/0500 UTC showed seas to 13 ft offshore Baja California Norte. However, seas have continued to build in large NW swell since that time. Seas north of Punta Eugenia are likely now 11-15 ft, and 8-12 ft offshore Baja California Sur, extending S to 18N, west of 111W. Moderate northerly winds prevail over the southern Gulf of California, with seas of 3 to 5 ft. A ridge across the eastern slopes of the Sierra Madre Mountains in Mexico continues to support a strong gap wind event across the Tehuantepec region. 0300 to 0400 UTC ASCAT data showed near gale force northerly winds to 30 kt across the Gulf of Tehuantepec, with fresh to strong winds of 20-25 kt extending downwind to near 13.5N95.5W. Seas across this area are 8 to 10 ft. Light to gentle winds prevail elsewhere across the Mexican offshore waters from the Tehuantepec region to Las Tres Marias. Seas across this area are 4-6 ft in mixed NW and SW swell. For the forecast, the cold front will gradually dissipate this afternoon as it continues moving southeastward. Fresh NW to N winds will continue behind the front through Thu morning on both sides of Baja California. A period of fresh to strong NW to N winds are expected west of Baja California Thu night. Similar winds are forecast in the northern Gulf of California Fri night. Large NW swell will continue to propagate across the offshore waters of Baja California through tonight, and gradually subside to 8-11 ft by late Thu. In the Gulf of Tehuantepec, the current strong gap wind event is expected to prevail through tonight before diminishing significantly in strength and areal coverage. Winds are expected to diminish to fresh to strong and remain confined to the Gulf of Tehuantepec Thu through Friday morning before shutting down. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR Fresh to strong NE to E winds prevail across the Papagayo region and extend to 90W, and are expected to pulse to strong at night through Thu night. Seas will generally persist at 6-7 ft. Gentle to moderate northerly winds and seas 3 to 4 ft in the Gulf of Panama are forecast to pulse nightly through Wed night. Moderate S to SW winds are south of the monsoon trough with seas to 6 ft in SW swell. Light to gentle variable winds are elsewhere. These conditions are forecast to remain for much of the week. REMAINDER OF THE AREA... The cold front has dissipated west of 116W. High pressure of 1025 mb is near 31N127W. The large NW swell continues over the Pacific. Earlier altimeter passes showed seas of 14-17 ft overnight across the Pacific from 20N-30N. Currently, seas are likely 12-16 ft north of 18N...highest north of 25N between 120W-130W. The swell will gradually subside as it builds southward, but seas of 12 ft will reach as far south as 12N latitude tonight into early Thu and gradually subside across the regional waters through Fri. Fresh trades prevail north of the ITCZ to 23N, and west of 115W to 140W. Fresh to locally strong trades will continue through Sat north of the ITCZ to 23N and west of 120W. $$ Hagen