000 AXPZ20 KNHC 221547 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1547 UTC Sun Oct 22 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: High pressure building southward across eastern Mexico in the wake of a cold front will help tighten the pressure gradient over the area. In response to the tighter pressure gradient, fresh to strong northerly flow will funnel through the Chivela pass into the Gulf of Tehuantepec starting late tonight. Winds will further increase to gale force by early Monday morning as the cold front moves through the western Gulf of Mexico. Winds may even approach minimal storm force by early Wednesday, with seas building to up to 18 ft by midweek. ...TROPICAL WAVES... The axis of a tropical wave is near 102W from 07N to 15N moving W at around 10 kt. Scattered moderate convection is noted from 07N to 10N between 98W and 101W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 11N85W to 08N120W. The ITCZ extends from 08N120W to 09N140W. Scattered moderate convection was noted from 08N to 10N between 120W and 125W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the special features section above for information on a developing gale event in the Gulf of Tehuantepec. Recent altimeter satellite passes indicated seas of 8 to 14 ft over much of the area offshore of Baja California, north of Cabo San Lazaro. Concurrent scatterometer satellite passes indicated strong northerly winds active in this area have diminished a bit, leaving the main component of the seas long period northerly swell. The swell is expected to decay below 12 ft through this afternoon, then subside further to below 8 ft off Baja California Sur and within 200 nm of the coast of Baja California Norte through late Monday. Looking ahead, gentle breezes associated with a weak pressure pattern along with slight to moderate seas will prevail by late week. High pressure over the Great Basin region of the western United States has strengthened winds over the Gulf of California. Fresh to strong winds are expected to continue through Tuesday, before diminishing as the area of high pressure shifts eastward and the pressure gradient weakens. Winds will be the strongest tonight through Monday when seas will peak around 8 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate winds will prevail over the forecast area the rest of the weekend, increasing to moderate to fresh S of the monsoon trough by Monday afternoon. NW swell originating from the Gulf of Tehuantepec will propagate into the offshore waters of Guatemala and El Salvador by the middle of next week. REMAINDER OF THE AREA... A set of large NW swell with seas near 15 ft will continue to propagate SE while gradually subsiding. Seas will subside to less than 12 ft this afternoon. Seas associated to this swell are expected to further subside, to less than 8 ft, by mid week. $$ Christensen