000 AXPZ20 KNHC 102146 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Sat Sep 10 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...SPECIAL FEATURES... A 1009 mb low pressure center is analyzed at 12.5N114W, and is associated with a tropical wave extending n from the low to 19N113W. The entire system is progressing w at about 12 kt. Scattered moderate isolated strong convection is currently observed e and over the nw semicircle within 240 nm either side of a line from 13N108W to 17N112W to 11N118W, but banding is intermittent. Fresh southerly winds, and combined seas of 6 to 9 ft in s swell, are observed out to 420 nm over the se semicircle of the low. Model guidance continues to indicate very favorable environmental conditions for this low to develop into a tropical cyclone over the next 5 days as it tracks nw across the tropics. ...TROPICAL WAVES... A tropical wave extends n from 12N95W across the Gulf of Tehuantepec and has been moving w at 10 to 15 kt. The only associated convection noted is a small cluster near 12N95W. Another tropical wave is over the w Caribbean along 81W, and will pass through Costa Rica and Nicaragua tonight into Sun accompanied by a few showers and tstms. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends off the Pacific coast of Costa Rica at 10N85W to 12N95W, then dips sw to 10N102W where is loses identity. Scatterometer winds indicate that the monsoon trough forms again at 14N105W, and turns sw through the 1009 mb low pressure center at 12.5N114W to 10N120W, then turns nw again through a 1013 mb low pressure center at 14N136W and continues sw to beyond 12N140W. Scattered moderate isolated strong convection is observed along, and to the s of the eastern segment of the monsoon trough within 240 nm either side of a line from 05N79W to 12N103W. Isolated moderate to strong convection is observed along the western segment of the monsoon trough within 90 nm either side of a line from 09N116W to 13N135W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A sub-tropical ridge axis extends from nw to se across the western portion of the offshore zones w of the Baja Peninsula. Gentle to moderate nw flow is expected through the period, except moderate to fresh nw flow will develop along the central Baja Peninsula briefly on Mon evening. A thermal trough will meander over the Baja Peninsula and across the northern Gulf of California through the period. This will maintain light, mostly southerly flow across the Gulf of California through Sun. Guidance is suggesting moderate s to sw flow over the northern gulf waters along 31N on Sun night, and fresh to moderate southerly flow in the same area on Mon night. The low level flow will clock to the nw across the entire Gulf of California on Wed. Model guidance indicates a fresh northerly surge will develop across, and just downstream of the Gulf of Tehuantepec on Sun and Tue nights with seas building briefly to 6 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light and variable winds forecast to the n of about 08N through the period, while moderate sw to w low level flow is expected across the EPAC waters generally to the s of 08N. Forecast combined seas of 4 to 7 ft across the entire area through the period primarily in mixing long-period sw and swell. REMAINDER OF THE AREA... Except as previously mentioned in the special features section, a weak trough analyzed from 27N132W to 32N127W will continue to drift w across the waters n of 25N and gradually fill through Mon. A 1020 mb surface high pressure e of the trough near 27N127W will lose identity as the sub-tropical ridge rebuild from w to e along 26N early next week after the trough dissipates. $$ Nelson