000 AXPZ20 KNHC 300842 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Wed Dec 30 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 0830 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N78W to 08N85W to 05N95W. The ITCZ continues from 05N95W to 05N100W to 05N125W to beyond 05N140W. Scattered moderate to isolated convection is noted from 05N to 07N between 125W and 135W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A pair of scatterometer satellite passes from 04-05 UTC indicated 15 to 20 kt NW to N winds across the offshore waters of Baja California, mostly gentle winds across the Gulf of California. NW swell of 8 to 12 ft is moving southward along the Baja California coast, with the leading edge of 8 ft seas reaching as far as the Revillagigedo Islands. The main weather driver is a mid to upper level trough moving across southern California, southern Arizona, the northern part of Baja California Norte and the northern Gulf of California. This feature will move eastward through this morning, supporting lower pressure over the southern Plains and north central Mexico. Ridging will build behind this trough over the Great Basin and eastern Pacific, tightening the pressure gradient and allowing NW winds to increase to near gale strength over the central and southern Gulf of California today and tonight, with seas building to 10 ft. NW winds will also increase off Baja California Sur by late Wed. Meanwhile the NW swell will continue to move southward, with 8 ft seas reaching as far south as Cabo Corrientes by Thu night. The fresh to strong NW winds will diminish Thu as the high pressure north of the area shifts east. But another, weaker deep layer trough moving through the region will support strong NW winds in the northern Gulf of California Thu night, and off Baja California Norte with a reinforcing set of NW swell to 12 ft. Winds and seas diminish Fri into Sat, although seas in excess of 8 ft will persist off Baja California in NW swell. Looking ahead, another set of NW swell will move into the area, with seas building to 12 to 14 ft in the waters north of Cabo San Lazaro late Sat through Sun night. Farther south, recent scatterometer satellite data from part of the Gulf of Tehuantepec and nearby land- based observations hint that winds have diminished to gentle to moderate speeds over the Gulf of Tehuantepec. Residual swell from the earlier gap winds is subsiding, and seas are likely 5 to 7 ft primarily in long- period SW swell. Looking ahead, the next gale force gap wind event in the Gulf of Tehuantepec by late Sat through Sun night as a cold front moves through the Gulf of Mexico. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Fresh to locally strong NE gap winds across the Gulf of Papagayo region is diminishing currently. Peak seas near 7 ft this morning are subsiding and will continue to be below 8 ft through the remainder of the week. The next round of fresh to fresh gap winds is possible by late Sat into early Sun. Elsewhere, gentle to moderate winds and slight to moderate seas in SW swell will persist over the Central American and equatorial waters through Sun night. REMAINDER OF THE AREA... Ridging extends from a 1032 mb high at 33N134W southeastward toward the Revillagigedo Islands. Various recent scatterometer satellite passes and a couple of ship observations indicate the pressure gradient between the ridge and the ITCZ to the south are producing fresh NE to E trades over the deep tropics west of 130W, with fresh to strong winds from 15N to 20N west of 130W. The trades will increase and become more extensive through tonight as the ridge strengthens. Recent altimeter satellite passes show large areas of 8-12 ft mainly north of 05N and west of 110W, likely due to NE wind waves and longer-period NW swell. The ridge will weaken Thu and shifts east ahead of an approaching cold front, allowing the NE trades to diminish back to moderate to fresh conditions. Maximum wave heights will subside to less than 12 ft, but the extent of the NW swell of 8 ft or greater will persist through Fri. The cold front will stall near 30N140W by Thu night, but reinforcing NW swell will accompany the front with wave heights 12 ft or greater covering the waters northwest of a line from Baja California Norte to 12N140W by Sat night through Sun. $$ Christensen