472 AXPZ20 KNHC 230916 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Sat Sep 22 2018 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 0915 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends W off the Caribbean coast of Colombia at 09.5N76W, and continues northwest across the extreme southwest Caribbean and across southern Nicaragua to the coast at 12N87W, then turns southwest to 09N102W, then northwest to 11N114W, then southwest to 09N126W, then northwest to beyond 11N140W. Scattered strong convection is noted within 75 nm either side of a line from 16N95W to 13.5N102.5W. Scattered moderate isolated strong convection is observed within 120 nm of the coasts of Colombia, Central america and Mexico from 78W to 107W. Isolated moderate to strong convection is observed elsewhere within the area bounded by 06N to 15N between 86W and 140W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A ridge extending from 21N116W to 19N108W will continue to gradually retract northwest as a surface low slowly develops near 13N105W tonight. The low will track northwest accompanied by tstms just beyond 250 nm seaward. Gentle to locally moderate cyclonic winds will shift northwest through the offshore waters mostly seaward of 200 nm, with the low reaching a position near 16N114 on Fri. By then southerly swells in the form of 7 to 9 ft seas will spread east along 17.5N between 110W and 115W. Moderate northwest flow is forecast west of the Baja California through early Mon, except becoming a fresh northwest breeze within 90 nm of the coast during the late afternoons and evenings. Gulf of California: Gentle to locally moderate variable winds forecast across the gulf waters north of 30N through Mon afternoon. Otherwise, light to gentle variable winds expected across the gulf waters through the middle of the week. Gulf of Tehuantepec: Fresh to locally strong nocturnal flow forecast through late Mon, then resuming on Mon night through Thu night with seas building to 10 ft downstream near 15.5N95W. A late week drainage event may assist in the development of a surface low near 09N99W on Fri. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Moderate to locally fresh east nocturnal drainage flow expected through Thu night with seas building to 8 ft. Light and variable winds are forecast elsewhere N of the monsoon trough which is meandering between 09N and 12N. Moderate southwest flow is forecast S of the monsoon trough through the middle of the week, increasing to moderate to fresh southwest monsoonal flow south of 10N late in the week as a surface low begins to develop near 09N99W on Fri, and then tracks northwest of the area on Sat accompanied by tstms. REMAINDER OF THE AREA... A trough extends southwest from 19N131W to 11N133W with isolated moderate to strong convection flaring within 150 nm of the trough. The trough will move west of the area by early Tue. A broad ridge continues across the subtropics accompanied by moderate to locally fresh anticyclonic flow south of 23N west of 120W. $$ Nelson