000 AXPZ20 KNHC 260950 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Mon Sep 26 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 0600 UTC surface analysis and satellite imagery through 0945 UTC. ...SPECIAL FEATURES... Tropical Storm Roslyn centered at 16.8N 119.5W at 27/0900Z, or about 750 nm wsw of the southern tip of the Baja California Peninsula, moving n-ne or 020 degrees at 4 kt. Estimated minimum central pressure is 1005 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Currently, scattered moderate isolated strong convection is observed over the se semicircle, within 120 nm either side of a line from 19n116W to 12N120W. Roslyn is forecast to maintain minimum tropical storm strength through late Tue, then lose tropical characteristics on Tue night with a 30 kt remnant low pres near 20.4N 117.0W at 06 UTC Sep 28. The remnant low will continue to gradually weaken late in the week. Refer to the latest NHC forecast/advisory under AWIPS/WMO headers WTPZ23 KNHC/TCMEP3, or visit the NHC website at http://hurricanes.gov for additional details. ...TROPICAL WAVE... A tropical wave is analyzed to the n of 08N along 99W and has been drifting westward. Scattered moderate to strong convection is noted w of the wave within 30 nm of the Pacific coast of Mexico between 97W and 101W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends w off the Pacific coast of northern Costa Rica at 11N85W to 11N96W, then dips sw to 10N112W where it loses identity. Scatterometer winds indicate that the monsoon trough resumes just sw of T.S. Roslyn at 14N122W, and continues wsw to the 1008 mb surface low previously mentioned near 11.5N139W. Scattered moderate isolated strong convection is observed within 120 nm of 08N85W. Isolated moderate and strong convection is noted elsewhere within 180 nm either side of a line from 06N82W to 11N100W to 08N109W, and from 07N to 14N between 120W and 137W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A sub-tropical ridge axis extends from nw to se across the offshore zones w of the Baja Peninsula terminating near 22N110W. Light to gentle nw winds are observed w of the Baja Peninsula with little change expected through tonight, then the gradient should further relax supporting light n to ne winds through late Tue. Gentle to occasionally moderate flow expected elsewhere along the Pacific coast of Mexico through tonight. Thereafter, the remnants of Roslyn will spread n across the extreme western waters of offshore zones PMZ015 and PMZ013 from Tue through Wed night, with a strong ne to e to se wind shift, and seas to a max of 11 ft. Moderate to fresh nw winds are expected across the northern Gulf of California this morning, then the gradient will relax supporting light and variable winds through Tue night, then becoming light n winds throughout the entire gulf waters on Wed. A cold front will pass through the sw Gulf of Mexico early this week, resulting in strong drainage flow across the Gulf of Tehuantepec beginning Wed night, and then pulsing through the upcoming weekend. Guidance has backed off on the winds reaching gale force. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light to gentle southerly winds expected n of about 05N, while gentle to locally moderate s to sw flow is expected s of 05N through the middle of the week. Combined seas of 3 to 6 ft primarily in mixing long-period sw and nw swell are expected this week. REMAINDER OF THE AREA... A 1008 mb low pressure is embedded in the monsoon trough near 11.5N140W. Scattered moderate isolated strong convection is noted within 120 nm either side of a line from 09.5N138W to 13N140W with banding features se of the center. The low is forecast to move w and become quasi-stationary near 13N142W late tonight, then move n during mid week accompanied by strong winds over its e semicircle that will spread e into the discussion area near 13N139W on Wed, surrounded by a larger area of 7 to 9 ft seas across the discussion waters from 11N to 17N w of 136W. Atmospheric and oceanic conditions will become more favorable for tropical cyclone formation in 3 to 5 days. $$ Nelson