711 AXPZ20 KNHC 250354 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Tue Sep 25 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 0345 UTC. ...SPECIAL FEATURE... A 1008 mb surface low at 14N106W is surrounded by scattered moderate isolated strong convection organizing in bands within 120 nm east and 210 nm west semicircles of the estimated center. Strong cyclonic winds within 150 nm northeast of center are expected to surround the low, or likely the tropical cyclone, within 24 hours. Additionally, the associated tightening pressure gradient has increased 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 101W and 117W. The low is forecast to move westerly to near 15.5N111.5W late Wed with minimal gale winds within 45 nm over the north semicircle surrounded by strong to near winds within 150 nm of the center. The track is uncertain until the system organizes, but for now expect fresh to strong easterly winds, and building seas across the Mexican offshore waters from 14N to 18N west of 104W through late Wed, then at least strong to near gale conditions spreading north across the offshore waters from 16.5N to 23N on Wed night through Sat, with large southerly swell propagating 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. ...TROPICAL WAVES... A tropical wave is analyzed from 04N99W to 17N98W with scattered moderate isolated strong convection north of 13N within 270 nm west of the wave axis. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends W off the Caribbean coast of Colombia at 09N76W, and continues west across the Gulf of Panama to the Pacific coast of Costa Rica at 09N84W to 09N91W, then turns northwest through a tropical wave at 12N99W to the surface low at 14N106W, then turns southwest to 12N112W to 10N139W. A north to south trough is analyzed from 09N139W to 17N138W with scattered moderate isolated strong convection north of 11N within 180 nm of the trough axis. Scattered moderate isolated strong convection is observed within 150 nm either side of a line from 09N80W to 08N94W, within 180 nm of 10N109W, within 75 nm of 17N116W, and from 06N to 14N between 120W and 135W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features paragraph above. A ridge extending from 22N116W to 21N112W will continue to gradually retract northwest during the middle of the week as the gale center, likely a tropical cyclone, tracks northerly beyond 250 nm seaward. Gentle to moderate northwest flow is forecast west of the Baja California through Fri, with much uncertainty thereafter. Gulf of California: Moderate to locally fresh southerly winds forecast across the gulf waters north of 30N through early Tue. Otherwise, light to gentle variable winds expected across the gulf waters through Fri. Gulf of Tehuantepec: Fresh to strong northerly flow forecast through Thu except briefly relaxing during the mid afternoons. A strong drainage event expected on Thu night into early Fri as a tropical low passes to the south. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh to locally strong east nocturnal drainage flow expected through early Wed with a surface low developing near 10N93W Wed night. Light and variable winds are forecast through Wed morning elsewhere north of the monsoon trough is meandering between 09N and 12N. Moderate southwest flow is forecast south of the monsoon trough. The pressure gradient will begin to tighten on Wed night as a surface low develops near 10N93W and moves west of the ares by early Fri. 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