000 AXPZ20 KNHC 290901 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 546 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends across Central America to 15N92W to low pres near 15N95W to low pressure near 13N113W to 10N140W. Scattered moderate isolated strong convection is noted from 05N to 08N between 81W and 100W. Scattered moderate convection is noted from 11N to 13N between 110W and 117W. ...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. 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... High pressure of 1021 mb centered near 31N140W extends a ridge southeast across the north waters. The pressure gradient between this area of high pressure 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. $$ AL