000 AXPZ20 KNHC 280900 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Mon Dec 28 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. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 07N78W to 09N83W to 05N100W. The ITCZ continues from 05N100W to 07N115W to beyond 09N140W. Scattered moderate convection is noted from 06N to 09N between 115W to 125W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Recent scatterometer satellite from 0430 UTC show moderate NW winds off the coast of Baja Califoria north of Punta Eugenia. A cold front is approaching from the west associated with a sharp deep layer trough moving across the eastern Pacific. The front will move across the northern portion of Baja California Norte and the northern Gulf of California later this evening. This pattern will support highly localized fresh to strong W gap winds over the northern Gulf of California along 30N as the front moves through. The front will start to weaken as it reaches the central Gulf of California and Baja California Sur by late Tue, then dissipate as it moves south of Los Cabos through Wed. NW winds will increase and seas will build over the Gulf of California Wed and Wed night as the sharp upper trough moves east of the region and broad ridging builds in its wake, then dissipate through Thu. Meanwhile, long period NW swell with combined seas of 8 to 10 ft is already evident off Baja California Norte and off Baja California Sur beyond 90 nm north of Cabo San Lazaro. This was confirmed by an altimeter satellite pass from 02 UTC. Reinforcing NW swell will accompany the front, with seas building to as high as 14 ft off Baja California Norte by early Tue, and NW swell in excess of 8 ft moving south of the Revillagigedo Islands and Cabo Corrientes by early Thu. The swell will start to subside Thu, but combined seas of 8 to 10 ft will persist along the Revillagigedo Islands and off Baja California through Fri night. Farther south, pulses of fresh to strong northerly gap winds with seas of 8 to 10 ft will persist into the Gulf of Tehuantepec through Tue, then diminish as high pressure north of the area weakens and shifts east ahead of low pressure moving into the western Gulf of Mexico. Looking ahead, gap winds to gale force are possible by late Sat. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Fresh to strong NE-E winds will continue to pulse across the Papagayo region through Tue as high pressure remains in place over the western Caribbean. Winds may briefly reach near gale force close to the coast during the early mornings due to enhanced drainage flow. Elsewhere, gentle to moderate winds will prevail on either side of the monsoon trough, except occasionally fresh near the Gulf of Panama. Long-period SW swell persist throughout the offshore waters of Central America through mid week. REMAINDER OF THE AREA... A cold front is moving eastward across the waters north of 25N, followed by fresh to strong NW winds and NW swell with combined seas of 12 to 16 ft. The tightening pressure gradient is already supporting fresh to strong NE trades winds from 17N to 20N west of 135W. Seas of 8 to 10 ft mainly due to an earlier round of NW swell cover the waters north of 05N and west of 115W. East of 115W, seas of 6 to 8 ft linger in a broad mix of swell from previous gap winds and longer period SW swell. The front will move east of the area through tonight, leaving 10 to 15 ft NW swell in the waters north of 20N, but with winds diminishing to moderate as weak high pressure builds in the wake of the front. The high pressure will continue to support fresh to strong trade winds farther south into the deep tropics, west of 130W into mid week. By Wed, the NW swell will support 8 to 11 ft seas over most of the waters north of 05N and west of 110W. Looking ahead, a new round of large, longer-period NW swell will move into the region, with 12 to 18 ft seas over much of the area northwest of a line from 30N130W to 20N140W by Fri night. $$ Christensen