000 AXPZ20 KNHC 150255 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Thu Sep 15 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 0200 UTC. ...SPECIAL FEATURES... Tropical Storm Orlene centered near 20.4N 120.4W at 0300 UTC moving west-northwest at 5 kt. Estimated minimum central pressure is 991 mb. Maximum sustained winds are 60 kt with gusts to 75 kt. Numerous moderate isolated strong convection is within 75 nm of the center. Orlene is no longer a hurricane, and is expected to continue weakening as it moves westward tonight and Thursday. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP1/WTPZ21 KNHC for more details. ...TROPICAL WAVES... A tropical wave is analyzed along 99W/100W north of 13N moving west at 10 kt. Scattered moderate convection associated with the wave and a nearby area of low pressure is located from 12N to 14N between 100W and 103W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A discontinuous monsoon trough axis extends from 11N86W to 1008 mb low pressure near 13N102W to 14N112W, then resumes from 13N122W to 12N130W to 16N140W. Scattered moderate isolated strong convection is within 75 nm west of the Central American coast between 85W and 93W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface ridge being squeezed between troughing over the northern Gulf of California and northwest Mexico is allowing northerly winds off Baja California Norte to increase to 15 to 20 kt. Winds and seas associated with Hurricane Orlene are well west of Clarion Island, and a southwesterly swell to 7 ft is affecting the waters beyond 150 nm west of Baja California Sur. This is expected to subside tonight. Farther south, a tropical wave moving slowly west along 99-100W will become less distinct in the next 24 hours as an area of low pressure area embedded within the monsoon trough near 13N102W becomes better organized. While no significant development is expected during the next two days, most global models indicate slow development of this system by this weekend as it moves northwest toward the Revillagigedo Islands with winds to 25 kt and seas 8 to 9 ft along the Mexican coast from Manzanillo to Cabo Corrientes by late Saturday or early Sunday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light to gentle winds are expected south of 07N through Sunday. Mainly moderate southwest to west low level flow is expected across the waters southward. Combined seas of 4 to 6 ft are likely across the entire area through the weekend in long-period southwest swell. Scattered showers are possible each night in the offshore waters. REMAINDER OF THE AREA... A sub-tropical ridge building from west to east across northern waters will support fresh trades through the weekend which will build seas to 8-9 ft from 13N to 20N west of 135W. Winds and seas will diminish this weekend as the ridge weakens and Orlene moves west. Southwest winds feeding into the monsoon trough are expected to increase late Thursday from 07N to 09N between 100W and 110W south of the developing low pressure area near 13N102W. $$ Mundell