000 AXPZ20 KNHC 271550 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1231 UTC Mon Nov 27 2017 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A tight pressure gradient is across southern Mexico between high pressure building over central Mexico and the western Gulf of Mexico and low pressure over the eastern and central Gulf of Mexico, along with relatively lower pressure over the deep tropics. This is resulting in gap winds to gale force through the Gulf of Tehuantepec continuing through this afternoon, diminishing to below gale force this evening as the high pressure weakens. Swell from the gap wind event with 8 ft or greater will reach more than 500 nm offshore of the Gulf of Tehuantepec. Pulses of gap winds to near gale force will persist through mid week, with another round of gale force winds is expected Friday night. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N84W to 07N95W to 08N110W, where it transitions to the intertropical convergence zone and continues to 10N137W to beyond 09N140W. Scattered moderate convection is from 08N to 10N between 90W and 95W, and from 10N to 12N between 115W and 122W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See Special Features paragraph above for information on the Gulf of Tehuantepec Gale Warning. A weakening cold front will move across the region from the west through tonight, then stall and dissipate from the northern Gulf of California to the central Baja California peninsula to 23N120W by late Tue. Fresh to strong NW winds will follow the front this afternoon off the coast of Baja California Norte, then later this evening into the overnight hours over the northern Gulf of California. The winds will diminish through tonight, but NW swell of 8 to 12 ft will follow the front as well, with the leading edge of 8 ft seas reaching the Revillagigedo Islands by Wed. Looking ahead, while this swell group decays below 8 ft from south to north, another reinforcing group of NW swell in excess of 8 ft will propagate into the waters off Baja California Norte by late Thu. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: A tight pressure gradient between high pressure over northern Central America and lower pressure across the southwest Caribbean will enhance overnight drainage effects and result in pulses of fresh to strong gap winds through the Gulf of Papagayo tonight into Tue morning, and to a lesser extent Tue night into Wed morning. Looking ahead, stronger pulses are likely later in the week. Seas will build to a maximize of around 7 ft each morning near sunrise. Light to gentle N to NE winds, and 3 to 5 ft seas are expected elsewhere through Friday north of the monsoon trough. Moderate southerly winds, and 4 to 6 ft seas, are forecast south of the monsoon trough. Northerly swell generated in the Gulf of Tehuantepec will reach the western part of forecast zone PMZ111 (offshore waters of Guatemala and El Salvador) seas to 10 ft through tonight, diminishing by early Tue. REMAINDER OF THE AREA... A weakening cold front from 30N121W to 23N130W will continue to weaken as it moves east of the area through Tue. Fresh to strong NE winds west of the front are diminishing rapidly as the front weakens, but NW swell of 8 to 13 ft will continue to propagate across the region with the leading edge of 8 ft seas reaching from the central Baja California peninsula to 10N140W by late Tue. Building high pressure to the north will allow fresh to strong NE winds north of 15N and west of 125W Tue night through late in the week. Farther south, recent altimeter satellite data indicated seas near 8 ft, likely in NW swell, S of 10N. This will decay below 8 ft through late tonight as it continues to propagate south of the area. $$ Christensen