000 AXPZ20 KNHC 011545 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC thu Sep 01 2016 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 1200 UTC surface analysis and satellite imagery through 1545 UTC. ...SPECIAL FEATURE... A broad area of low pressure embedded within the monsoon trough is analyzed as a 1009 mb surface low near 12N92W at 1200 UTC. Currently scattered moderate isolated strong convection is observed w of the low center, within 120 nm either side of a line from 09N92W to 14N97W. Although the convection is intermittent and disorganized, atmospheric and oceanic conditions are favorable for rapid intensification, and this low has the potential tropical cyclone development as it continues northwestward to near 12.5N95.5W on Fri, and near 14N97W on Sat. Fresh southwesterly flow is observed s of the monsoon trough axis, roughly within the area from 08N to 11N between 103W and 110W, with combined seas of 6 to 8 ft primarily due to 5 to 6 second southwest swell. As the pressure gradient tightens tonight, the southerly flow should increase to strong s of the low, within the area bounded by 09N to 11N between 95W and 104W. Although the array of global model guidance differs slightly on track, most suggest strong to near gale conditions could develop over the e semicircle of the low beginning late Sat. These winds, and the resultant high seas, could reach the Pacific coast of Mexico between 96W and 101W on Sun. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends w from the Pacific coast of Nicaragua at 11N86W through an embedded 1009 mb low pressure center at 12N92W, to 15N104W to a 1010 mb low pressure at 10N118W to beyond 13N140W. Scattered moderate isolated strong convection is observed within 150 nm either side of a line from 06N78W to 12N90W, within 90 nm of 10N101W, within 90 nm either side of a line from 09N110W to 09N116W and within 120 nm either side of a line from 09.5N123W to 12N133W to 10N140W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See special features section above for discussion on a tropical low, or tropical cyclone, developing sw of the Gulf of Tehuantepec on Sat, and tracking northward reaching near 14N100W on Sun. Otherwise, a sub-tropical ridge axis extends se to near 17N115W, and will maintain gentle to moderate nw flow, with 5 to 7 ft combined seas across the northern waters generally to n of 23N and w of 116W, and 3 to 5 ft seas elsewhere within 250 nm of the Pacific coast of Mexico. Little change expected through Sun, then fresh nw flow will develop along the Baja Peninsula from 25N to 29N. A thermal trough will meander over the Baja Peninsula, and across the northern Gulf of California supporting light and variable flow across the Gulf of California through Mon night, except increasing to moderate to fresh southerly flow between 30N and 31N on Fri night, and fresh to locally strong southerly flow expected in the same area on Sat night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... See special features section above for discussion on a tropical low near 12N92W that is expected to move n across the far western waters of offshore zone PMZ111 tonight, with fresh to strong sw flow spreading across the same area on Fri. Gentle to moderate southwesterly winds expected elsewhere through Fri, then the gradient will relax with gentle w to nw flow expected elsewhere n of 05N through Mon. Moderate southerly flow forecast s of 05N. REMAINDER OF THE AREA... Except as previously mentioned, a quasi-stationary surface ridge will extend from near 32N140W to near 15N114W through Fri night. Fresh to strong ne to e winds, with 8 to 12 ft seas, associated with tropical cyclone Lester are observed w of a line from 26N140W to 20N136W to 14N140W. These winds and seas will shift w of 140W on Sat. Moderate to fresh ne to e flow will develop on Fri and continue through late Sat s of the ridge and n of the monsoon trough, with combined seas of 4 to 7 ft, with little change through the weekend. Moderate to fresh n to ne flow is forecast n of the ridge, with 5 to 7 ft combined seas through tonight, then the gradient will relax with moderate n flow expected Fri through Mon. An ill-defined tropical low currently near 10N118W will move w reaching near 11N124W on Sat with low chance of development through that time. Fresh sw flow within 270 nm se quadrant of low through Fri. $$ Nelson