000 AXPZ20 KNHC 112152 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Sun Sep 11 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... Tropical Storm Orlene was centered at 16.3N 117.7W, or about 680 sm sw of the southern tip of the Baja California Peninsula, and is moving northwest, or 310 degrees, at 12 kt. The estimated minimum central pressure is 1003 mb. The maximum sustained winds are 45 kt, with gusts to 55 kt. Numerous strong convection is currently observed within 150 nm of Orlene. Continued strengthening is forecast with Orlene reaching hurricane strength in about 24 hours. Refer to the latest NHC forecast advisory at WMO/AWIPS headers WTPZ21 KMIA/MIATCMEP1 for additional details. ...TROPICAL WAVES... A tropical wave is analyzed n of 08N along 83W, and will reach the Pacific coast of Costa Rica and Nicaragua late tonight accompanied by a few showers and tstms. A tropical wave extends n from 06N97W to 16N97W, and has been moving w at 10 to 15 kt. Isolated moderate and strong convection is within 180 nm either side of the wave axis. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends w off the Pacific coast of Costa Rica at 09N83W to 11N93W to 12N108W where is loses identity. Scatterometer winds indicate that the ITCZ forms near 14N135W, and continues sw to beyond 12N140W. Except as previously described near the tropical wave along 97W, scattered moderate isolated strong convection is observed within 180 nm either side of a line 05N78W to 13N107W. Isolated moderate and strong convection is noted sw of Orlene within 300 nm either side of a line from 10N120W to 15N131W. ...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 late Thu. 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 for the next few days. The exception is that model guidance is suggesting moderate s to sw flow will develop briefly over the northern gulf waters along 31N late tonight, and then develop again on Mon night and then persist through early Tue night. The low level flow will clock to the nw across the entire Gulf of California on Wed and continue through Thu. Model guidance indicates a fresh to strong northerly surge will briefly develop across the Gulf of Tehuantepec tonight with seas building briefly to 6 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light to gentle winds are forecast to the n of about 08N through the period, while moderate sw to w low level flow is expected across the discussion 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 concerning TS Orlene, a weak and broad trough covers the waters n of 27N between 125W and 135W. The trough will drift se and further weaken through Tue as the sub-tropical ridge rebuilds from w to e along 26N during the middle of the week. $$ Nelson