000 AXPZ20 KNHC 280918 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0918 UTC Tue Nov 28 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 0600 UTC surface analysis and satellite imagery through 0800 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A tight pressure gradient is across southern Mexico between high pressure over central Mexico and the western Gulf of Mexico and lower pressures in the deep tropics. The combination of this gradient and nocturnal drainage flow are resulting in gale force gap winds through the Gulf of Tehuantepec this morning. The winds should subside below gale force around 1200 UTC later this morning. Lingering NE swell from the gap wind event with 8 ft or greater seas will reach more than 500 nm offshore of the Gulf of Tehuantepec. Another round of gale force winds are expected Wed night and again Friday night. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N84W to 07N95W to 08N105W to 08N113W, where it transitions to the intertropical convergence zone and continues to 08N120W to 09N130W to beyond 10N140W. Scattered moderate convection is from 05N to 11N between 91W and 96W. Isolated moderate convection is from 09N to 14N between 104W and 118W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See Special Features paragraph above for information on the Gulf of Tehuantepec Gale Warning. A cold front will move across the region from the west N of 28N through this morning, then dissipate near the central Baja California peninsula later today. Fresh to locally strong NW winds are occurring off the coast of Baja California Norte as well as over the northern Gulf of California. NW swell of 8 to 12 ft will follow the front, with the leading edge of 8 ft seas reaching the Revillagigedo Islands by late Wed or early Thu. Seas W of Baja California and Revillagigedo Islands will remain above 8 ft through late week, as another reinforcing group of NW swell in excess of 8 ft propagates into the waters. 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 through this morning, and to a lesser extent tonight into Wed morning. 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 Sat 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 has reached the western part of forecast zone PMZ111 (offshore waters of Guatemala and El Salvador) with seas to 9 ft, diminishing through this morning. Additional large swell will reach the western portion of zone by Thu through the end of the week. REMAINDER OF THE AREA... An active upper level jetstream is supporting clusters of moderate convection from 21N to 28N between 125W and 140W. A large area of NW swell of 8 to 15 ft will continue to propagate across the region with the leading edge of 8 ft seas reaching from the central Baja California peninsula to 05N140W by this evening, and then from 15N110W to the equator along 140W by early Thu. Building high pressure to the north will allow fresh to strong NE winds north of 15N and west of 125W Wed through late in the week. A re- enforcing batch of NW swell will reach the waters late this week, as seas of 8 to 12 ft cover nearly the entire forecast waters S of 30N W of 110W Fri through the upcoming weekend. $$ Latto