000 AXPZ20 KNHC 092155 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Fri Sep 09 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 11N110.5W, and is associated with a tropical wave extending ne from the low to 16.5N108W. The entire system is progressing w at about 12 kt. Scattered moderate isolated strong convection is currently observed within 270 nm over the nw semicircle. Fresh winds, and combined seas of 6 to 9 ft, are observed out to 420 nm over the e semicircle of the low. Model guidance indicates favorable environmental conditions for this low to gradually develop tropical cyclone characteristics over the next 5 days as it tracks nw across the tropics. ...TROPICAL WAVES... The southern segment of a tropical wave is moving w along the Pacific coast of Guatemala with a cluster of convection now decaying near 12.5N91W. Another tropical wave is over the w Caribbean along 76W, and will pass through the Gulf of Panama tonight accompanied by showers and tstms. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... Scatterometer winds indicate that the monsoon trough forms at 12N94W, and extends w through the 1009 mb low pres at 11N110.5W, then turns nw to 14N125W, and continues w to beyond 12N140W. Scattered moderate isolated strong convection is observed within 120 nm of 06N80W, within 75 nm either side of a line from 08N85W to 06N93W, s of the monsoon trough within 60 nm either side of a line from 13N91W to 09N98W to 12N105W. Isolated moderate and strong convection is noted over and to the s of the monsoon trough within 90 nm either side of a line from 13N124W to 11N139W. ...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 overnight. A thermal trough will meander over the Baja Peninsula and across the northern Gulf of California through the period. This will maintain light and variable flow across the Gulf of California through Sun. Guidance is suggesting moderate s to sw flow along 31N on Sun night, and fresh to moderate southerly flow in the same area on Mon night. Model guidance indicates a fresh northerly surge will develop across, and just downstream of the Gulf of Tehuantepec on Sun night 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 07N through the period, while moderate sw to w flow is expected across the EPAC waters generally to the s of 07N. Forecast combined seas of 4 to 7 ft across the entire waters 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 27N127W to 32N125W will drift w across the waters n of 25N over the weekend, with a surface high pressure developing e of the trough near 27N124W tonight. The ridge will rebuild from w to e along 26N early next week after the trough dissipates. A weak, 1014 mb surface low is analyzed near 18N126W with a trough extending ne to 21N124W. Intermittent moderate showers have been observed near the trough. The low is forecast to dissipate tonight. $$ Nelson