000 AXPZ20 KNHC 211445 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Sun May 21 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 1545 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The Monsoon Trough begins at a 1008 mb surface low over the Caribbean Coast of Colombia at 11N76W, and extends w to the Pacific coast of Costa Rica at 11N86W, then continues nw to 12N92W, then dips sw to 08N120W where scatterometer winds indicate that the ITCZ forms, and continues sw to beyond 05N140W. Scattered moderate isolated strong convection is noted within 240 nm either side of a line from 02N78W to 13N98W, and within 90 nm either side of a line from 07N109W to 04N120W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A nw to se orientated ridge extends across the EPAC waters just beyond 250 nm of the coast of the Baja California Peninsula, with the associated pressure gradient forecast to maintain a moderate nw breeze w of the Baja through early Tue, with combined seas of 3 to 5 ft in mixed s and nw swell. The pressure gradient will tighten somewhat on Tue, with fresh nw flow forecast across the waters n of 25N within 90 nm of the Baja Peninsula through Thu night, with combined seas of 4 to 6 ft. AND Gulf of California: Light and variable winds are expected through Thu, except becoming a gentle sw breeze during the overnight hours with seas of 1 to 3 ft. Guidance is suggest a fresh to locally strong sw breeze along 30N on Thu night. Mexican offshore waters s of 16N including the Gulf of Tehuantepec: Model guidance has begun to agree that a weak surface low will soon develop along the monsoon trough near 11N95W, and drift w and gradually dissipate through Wed night. Expect moderate cyclonic flow, and 4 to 7 ft seas, through early Wed, with the low level flow diminishing to a light southerly breeze on Wed night through Thu night as the low weaken to a n to s orientated trough. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... To the n of 09N expect light and variable flow to gradually become a moderate se to s breeze e of a surface low forecast to develop near 11N95W by this evening, with associated seas building 4 to 6 ft, except 6 to 8 ft seaward of 200 nm. Winds should diminish on Tue with light and variable flow on Wed and Thu and seas of 3 to 6 ft. Moderate southerly flow expected through the Thu night, with combined seas of 6 to 9 ft primarily due to long period s swell today. The seas forecast to subside to 4 to 6 ft by Mon night, with little change then expected through Thu night. REMAINDER OF THE AREA... A ridge will meander from near 32N140W to near 13N102W through middle of the week. Moderate anticyclonic flow, with combined seas of 4 to 6 ft, is expected through late Mon. A weak trough will sweep e across the waters n of 30N on Tue and Wed accompanied by a slight w to nw wind shift but followed by long- period nw swell that build seas to 6 to 8 ft along 32N between 120W and 135W on Wed and Thu. Cross equatorial southerly swell, in the form of 6 to 8 ft seas, currently across the tropics elsewhere s of 10N e of 108W will gradually subside to less than 8 ft tonight. $$ Nelson