000 AXPZ20 KNHC 221409 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Mon May 22 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 1800 UTC surface analysis and satellite imagery through 1400 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The Monsoon Trough begins at a persistent surface low over the Caribbean Coast of Colombia near 10.5N75W, and extends w to the Pacific coast of Costa Rica at 09N83W and through an embedded 1009 mb surface low at 10N87W to 11N94w, then turns sw through an embedded 1008 mb surface low at 09N100W. The monsoon trough extends sw from the western low to 07N122W where scatterometer winds indicate that the ITCZ forms, and continues w to beyond 07N140W. Scattered moderate isolated strong convection is noted within 150 nm either side of a line from 04N79W to 14N95W to 09N104W with clusters covering most of the Gulf of Tehuantepec. Similar convection is observed within 90 nm either side of a line from 07N112W to 09N122W, and along the ITCZ within 75 NM either side of of a line from 08N133W to 06N140W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A nw to se orientated ridge extends across the far offshore to the w of 100W, with the associated pressure gradient maintaining a moderate nw breeze w of the Baja through Tue, with combined seas of 3 to 5 ft in mixed s and nw swell. The pressure gradient will tighten somewhat late Tue, with fresh nw flow and 4 to 6 ft seas, spreading s across the waters to the n of 25N within about 90 nm of the Baja Peninsula, with little change then expected through Thu. Guidance is suggesting these conditions will spread further s to 23N on Fri. Gulf of California: Light and variable winds are expected through Wed, except becoming a gentle sw breeze during the overnight hours with seas of 1 to 3 ft. Guidance is suggesting fresh to locally strong sw breeze along 30N on Wed night to the s of a surface low that will develop and meander near 31N114W on Thu and Fri. Mexican offshore waters s of 16N including the Gulf of Tehuantepec: A broad low to mid level cyclone is analyzed along the monsoon trough near 09N100W with a surface trough extending ne to to the Gulf of Tehuantepec resulting in moderate ne to e to se flow across the Mexican offshore waters s of 16N. The low will gradually dissipate with light sw flow forecast across these waters by Thu morning as the monsoon trough shifts northward. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The monsoon trough extends e to w across the area between 10N and 12N with an embedded low currently near 10N87W. Moderate e to se winds will continue n of the trough through Tue, then becoming a light sw breeze through the rest of the week as the monsoon trough shifts n, with combined seas of 3 to 5 ft primarily in sw swell. Light to moderate southerly flow expected s of the monsoon trough with 4 to 6 ft in sw swell. REMAINDER OF THE AREA... A ridge currently extending se from 32N140W to near 11N101W will shift sw to along a position from 32N142W to 11N120W by mid week as a weak trough sweeps e across the waters n of 30N on Tue and Wed accompanied by only a slight w to nw wind shift, but followed by long-period nw swell that build seas to 6 to 8 ft from 30N to 32N between 120W and 135W on Wed night and Thu. Elsewhere n of the ITCZ and monsoon trough moderate anticyclonic flow, with combined seas of 4 to 6 ft, is expected this week. $$ Nelson