986 AXPZ20 KNHC 240915 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Mon Sep 24 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. ...SPECIAL FEATURE... A broad area of low pressure is analyzed as 1009 mb surface low near 13.5N 102.5W. Scattered moderate isolated strong convection is observed within 90 nm south of the low with intermittent banding features. The associated tightening pressure gradient will increase the southwesterly monsoonal flow to a fresh to locally strong breeze well south of the low, across the tropical waters from 06N to 12N between 178W and 116W over the next 24 hours. Environmental conditions are very favorable for tropical formation as this low tracks west-northwest over the next few days. Much uncertainty at this time, but for now expect fresh to strong easterly winds, and building seas, to spread north across the offshore waters from 16.5N to 23N on Wed through Sat, with southerly swell, in the form of 8 to 12 ft seas, to propagate north across the waters west of the Baja Peninsula during the upcoming weekend. Refer to the East pacific tropical Weather Outlook under WMO/AWIPS headers ABPZ20 KMIA/MIATWOEP for additional information. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends W off the Caribbean coast of Colombia at 09N76W, and continues west across the extreme southwest Caribbean to the Pacific coast of Costa Rica at 10N86W through a tropical wave along 10N94.5W, then turns northwest through the surface low at 13.5N 102.5W, then turns southwest to 12N109w to to 13.5n116.5W to 10N140W. Scattered moderate isolated strong convection is observed across the gulfs of Panama and Tehuantepec and within 75 nm of 20N106W. Isolated moderate and strong convection is noted elsewhere within 270 nm either side of a line from 05N82W to 13N98W, and from 07N to 17N between 98W and 137W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features paragraph above. A ridge extending from 22N116W to 20N108W will gradually retract north during the middle of the week as a surface low, possibly a tropical cyclone, tracks northerly beyond 250 nm seaward. Gentle northwest flow is forecast west of the Baja California through mid week, except becoming a moderate 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 this evening. Otherwise, light to gentle variable winds expected across the gulf waters through the middle of the week. Gulf of Tehuantepec: Strong northerly flow forecast through late this afternoon, then fresh to locally strong nocturnal drainage forecast to resume tonight with a strong event expected on Fri night. 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 north of the monsoon trough which is meandering between 09N and 12N. Moderate southwest flow is forecast south of the monsoon trough. REMAINDER OF THE AREA... See the Special Features paragraph above. A broad ridge continues across the subtropics accompanied by moderate to locally fresh anticyclonic flow south of 23N west of 120W. $$ Nelson