000 AXPZ20 KNHC 291546 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1546 UTC Fri Sep 29 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. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends across Central America to 11N85W to 1007 MB low pres near 15N95W to 11N140W. Scattered moderate to isolated strong convection off Mexican coast between 95W and 103W. Scattered moderate convection from 10N to 12N between 108W and 114W. Scattered moderate from 04N to 08N between 80W and 100W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Fresh to strong gap winds will develop over the Gulf of Tehuantepec tonight as a ridge builds across the western Gulf of Mexico and the eastern slopes of the Sierra Madre Mountains. This gap wind event will persist during the upcoming weekend. Elsewhere, a ridge will dominate the waters west of the Baja California Peninsula producing gentle to moderate northerly winds and seas of 4-5 ft through Saturday. Northerly swell will propagate into the waters west of Baja California Norte Sunday, building seas to 6-8 ft. Fresh to locally strong S-SW winds are expected over the northern Gulf of California Sunday night through Tuesday as low pressure develops over the area. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... An active monsoon trough is currently across Central America and adjacent waters. The trough will remain close enough to the coast, either inland or just offshore, to produce active convection, primarily during the late afternoon and evening hours, over portions of Central America as well as the adjacent coastal waters during the next few days. Moderate SW to W winds are expected south of the monsoon trough through Friday, with moderate to locally fresh SW to W winds during the upcoming weekend. Long period SW swell will continue to propagate across the offshore waters with seas of 5-7 ft through the weekend. Looking ahead, broad low pressure developing over Central America will cause monsoonal winds to surge to fresh to strong speeds west of Costa Rica from Sunday night through at least the middle of next week. Seas of 8 ft or higher will affect the waters beyond 200 nm off the coast from Nicaragua to Guatemala. REMAINDER OF THE AREA... A ridge extends from 1021 mb high pressure near 32N140W to the south of the Baja peninsula. The pressure gradient between the ridge and the monsoon trough is supporting gentle to moderate winds. Looking ahead, northerly swell will propagate into the waters north of 25N between 120W and 130W Sun through Mon night, building seas up to 11 ft along 30N by Monday. Farther south, cross equatorial southerly swell will propagate across the waters south of 02N between 105W and 135W by Tuesday, with seas building to 8-10 ft. $$ Christensen