000 AXPZ20 KNHC 251540 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1539 UTC Sat Nov 25 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 1530 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A tight gradient will set up across southern Mexico between high pressure north of the area and relatively lower pressure over the deep tropics. This will result in strong gap winds in the Gulf of Tehuantepec starting late tonight, enhanced by local drainage effects. Winds will reach gale force by late Sun with seas building to 10 ft. The gales will increase to 40 kt by early Mon with seas building to 17 ft downstream. Swell from the gap wind 8 ft or greater will reach more than 500 nm offshore of the Gulf of Tehuantepec by late Mon. The high pressure weakens and shifts east Tue, allowing gale force winds to diminish. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N84W to 10N110W, where it transitions to the intertropical convergence zone and continues to 10N130W. Scattered moderate convection is observed within 60 nm south of the monsoon trough between 95W and 100W. Scattered moderate to isolated strong within 120 nm south of the ITCZ between 120W and 125W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See Special Features paragraph above for information on the Gulf of Tehuantepec Gale Warning. A weak ridge centered around 600 nm off Baja California will maintain light to gentle breezes and slight seas into early next week. The ridge will weaken early next week as a cold front moves across the region from the west, accompanied by fresh to strong NW winds off Baja California Norte late Mon. Seas will build Mon as well as NW swell of 8 to 12 ft will move into the area off Baja California Norte, then continue to propagate off Baja California Sur late Mon, reaching the Revillagigedo Islands by mid week. Winds diminish Tue, but seas in excess of 8 ft will persist through late week as another round of reinforcing swell moves into the region. Strong NW winds will follow the front across the northern and central Gulf of California Mon night and early Tue. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to locally strong NE winds are occurring across and downstream of the Gulf of Papagayo early this morning, with the assistance of the nocturnal drainage flow. Seas have built to 6- 7 ft downstream of the gulf. Expect a typical nocturnal maximum of around 25 kt across the region through early Tue morning, diminishing to 15-20 kt by mid afternoon. Seas will maximize to around 7 ft each morning near sunrise, and will likely build to 8 ft early Monday morning, and early Tue morning. Moderate to locally fresh NE winds are expected across the Gulf of Fonseca each night through Tue. Light to gentle N to NE winds, and 3 to 5 ft seas are expected elsewhere through Sun night to the N of the monsoon trough which has been meandering between 09N and 11N. Moderate southerly winds, and 4 to 6 ft seas, are forecast S of the monsoon trough. REMAINDER OF THE AREA... A cold front is over the NW waters and extends from 30N134W to 21N140W while a reinforcing or secondary cold front is approaching 30N140W. Fresh to strong S to SW winds are noted N of 27N W of 135W. Fresh to strong NW winds and seas up to 10 or 11 ft will follow the secondary front this afternoon. The fronts are forecast to merge on Sun as they move eastward and approach 125W. Recent altimeter data indicated seas of 8 to 10 ft from 10N to 20N west of 125W. This will propagate southward across the equator while decaying through early Mon, just ahead of reinforcing NW swell entering the discussion area tonight, encompassing most of the region north of 10N through mid week. $$ Christensen