000 AXPZ20 KNHC 300328 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 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 0300 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N78W to 05N95W. The ITCZ continues from 05N95W to 07N115W to 05N130W to beyond 05N140W. Scattered moderate convection is noted from 05N to 10N between 125W and 135W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 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. Moderate to fresh NW winds are ongoing off Baja California, with mostly gentle winds across the Gulf of California. 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 tonight, 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 Wed and Wed night, 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 fresh 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, land based surface observations over the isthmus of Tehuantepec show winds have diminished to gentle to moderate speeds. This is hinting that gap winds over the Gulf of Tehuantepec have diminished as well. Gap winds are estimated to be 15 to 20 kt currently, mainly due to localized drainage flow, and this should diminish later Wed morning. Seas are likely still reaching up to 8 ft 250 nm downstream of the coast in a combination of residual NE swell from the earlier gap winds, but also due to longer 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 strong NE gap winds will pulse across the Gulf of Papagayo region through tonight as high pressure remains in place over the W Caribbean. Winds will then diminish as the high pressure weakens and shifts east. Peak seas that reached 8 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 1030 mb high at 33N133W southeastward toward Baja California Sur. 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 Wed night as the ridge strengthens. Seas will peak at 10-12 ft due to NW swell and NE wind waves. Meanwhile NW swell in excess of 8 ft persists across the region north of 05N and west of 110W. The ridge will weaken Thu and shift 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. While another cold front will stall near 30N140W by Thu night, 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