504 AXPZ20 KNHC 220400 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 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 0000 UTC surface analysis and satellite imagery through 0300 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends W off the Caribbean coast of Colombia at 10N75W, and continues west across the extreme southwest Caribbean and across northern Costa Rica to the Pacific Coast of Costa Rica at 11N85W to 09N104W TO 14N125W where it loses identity in the cyclonic circulation associated with a 1010 mb surface low at 15N127W. The monsoon trough resumes southwest of the low at 14.5N129W and continues southwest to 13N140W. Isolated moderate and strong convection is noted within the area bounded by 19N108W to 12N90W to 04N90W to 06N120W to 19N108W. Scattered moderate isolated strong convection is observed within 150 nm either side of a line from 11N130W to 09N140W. Scattered moderate isolated strong convection is noted within 30 nm either side of lines from 07N81W to 10.5N86W and from 15.5N97W to 17N101W, and within 45 nm of 21N105.5W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A ridge extending from 22N116W to 15N100W will gradually retract northwest as a surface low slowly develops near 13N106W on Sun night, and then tracks northwest accompanied by tstms just beyond 250 nm seaward. However, moderate cyclonic winds will shift northwest through the offshore waters seaward of 200 nm with the low reaching a position near near 15.5N109.5W on Wed and near 18N115W on Fri. 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 the weekend. Otherwise, light to gentle variable winds expected across the gulf waters through the middle of next week. Gulf of Tehuantepec: Fresh to locally strong nocturnal flow forecast on Sat night through Mon night, with a strong northerly drainage event expected on Thu night with seas building to 9 ft. The late week event may assist in the development of a surface low near 12N95W late next week. 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 Mon night. Light and variable winds are forecast elsewhere N of the monsoon trough which is meandering between 09N and 11N. Moderate southwest flow is forecast S of the monsoon trough through the middle of next week. Moderate to fresh southwest monsoonal flow is expected south of 10N late next week as a surface low begins to develop near 13N93W on Thu, and then tracks northwest of the area on Fri accompanied by tstms. REMAINDER OF THE AREA... A 1010 mb surface low is analyzed near 15N127W with a low level trough extending northeast to near 20N122W with isolated strong convection flaring within 60 nm of the trough. The surface low will weaken to an inverted trough this weekend, and move west of the area by the middle of next week. A broad ridge continues across the subtropics accompanied by moderate to locally fresh anticyclonic flow south of 23N west of 120W. $$ Nelson