000 AXPZ20 KNHC 120312 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Mon Sep 12 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 0000 UTC surface analysis and satellite imagery through 0230 UTC. ...SPECIAL FEATURES... At 0300 UTC...Tropical Storm Orlene was centered at 16.6N 118.3W, or about 700 sm sw of the southern tip of the Baja California Peninsula, and is moving northwest, or 305 degrees, at 08 kt. The estimated minimum central pressure is 1001 mb. The maximum sustained winds are 55 kt, with gusts to 65 kt. Numerous strong convection is currently observed within 90 nm of Orlene surrounded by scattered moderate isolated strong out to 180 nm from the center. Continued strengthening is expected and the forecast is for Orlene to reach minimal hurricane strength in 12 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 84W, and will reach the Pacific coast of Costa Rica and Nicaragua tonight accompanied by isolated showers and tstms. A tropical wave extends n from 06N98W to 16N98W, and has been moving w at 10 to 15 kt. Isolated moderate and strong convection is within 270 nm either side of the wave axis. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends Nw off the Pacific coast of Costa Rica at 10N86W to 13N91W, then turns sw to 11N96W to 13N107W where is loses identity. Except as previously described near the tropical wave along 98W, scattered moderate isolated strong convection is observed over the Gulf of Panama and along the coast of Guatemala within 60 nm of 14N91.5W, and within 180 nm either side of a line 08N86W to 13N108W. Isolated moderate and strong convection is noted sw of Orlene within 300 nm either side of a line from 09N120W to 15N132W. ...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 briefly along the central Baja Peninsula 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 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 surface winds 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 just to the s of the trough base along 26N during the middle of the week. $$ Nelson