000 AXPZ20 KNHC 240246 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 246 UTC Sat Sep 24 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 0300 UTC. ...SPECIAL FEATURES... A broad and elongated area of low pressure persists within the monsoon trough near 12N118W with an estimated pressure of 1007 mb. The low pressure is slowly getting better organized although convection has recently weakened. Scattered moderate convection is observed within 240 nm in the northeast semicircle of the low pressure, and within 180 nm south of the monsoon trough to the southwest of the low center. Fresh to strong south to southwest winds persist within 270 nm of the southeast quadrant of the low pressure. Seas are 8 to 12 ft in this area with some added component of southwest swell. Atmospheric conditions are expected to become favorable for tropical cyclone formation through the next 48 hours. Even in the absence of tropical cyclone development, the pressure gradient should tighten with minimal gale winds developing late Saturday as the low forecast nears 15N117W. The consensus solution among global models shows the low moving northward and passing west of Clarion Island by late Sunday or early Monday morning, either as a tropical cyclone or gale center. There is still a lot of uncertainty in the future track and intensity of this system. Please refer to the latest Graphical Tropical Weather Outlook for more information at http://hurricanes.gov. ...TROPICAL WAVES... A tropical wave is analyzed north of 10N along 94W, moving west at 10 to 15 kt. Scattered moderate convection is noted where the tropical wave moves over the monsoon trough, from 10N to 12N between 91W and 93W. The tropical wave enhanced overnight convection off the coast of northern Central America and southern Mexico last night, and will likely do so again tonight. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 11N85W to 09N101W, resuming from the 1007 mb low pressure near 12N118W to 1009 mb low pressure 12N130W to beyond 10N140W. Scattered moderate convection is noted within 90 nm south of the monsoon trough between 91W and 93W, within 180 nm south of the monsoon between 120W and 126W. Scattered moderate convection within 90 nm north of the axis between 128W and 133W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Moderate to fresh northwest to north winds are noted off Baja California Norte between 1027 mb high pressure centered near 34N135W and a surface trough over the Gulf of California. Ship observations and altimeter satellite data also indicate seas to at least 12 ft in northerly swell in this area as well. Swell in excess of 8 ft is likely reaching as far south as 24N, but will start to gradually decay from south to north to below 8 ft through off the Pacific coast of Baja California through Saturday night. Meanwhile winds and seas on the periphery of what will likely be the approaching developing gale center/tropical cyclone will bring increased southerly flow and seas of 8 to 12 ft to the waters around Clarion Island from late Saturday through Sunday. If the forecast holds, the low pressure will eventually bring strong winds and high seas to the southern tip of Baja California Sur, but there is remains a lot of uncertainty. Meanwhile lingering long period southwest swell persists over the waters of southern Mexico south of 20N with seas mainly 5 to 7 ft. An upper low centered of the coast of Sinaloa will again enhance overnight and early morning convection between Cabo Corrientes and Cabo San Lucas. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light east to southeast winds are expected north of about 12N while gentle to locally moderate south to southwest flow is expected south of 12N through the middle of the next week. Combined seas of 5 to 7 ft will continue through tonight primarily in mixing long- period southwest and northwest swell, then begin to subside to 4 to 6 ft Saturday through early next week. REMAINDER OF THE AREA... A 1009 mb low pressure area is analyzed along the monsoon trough near 12N128W. The low is forecast to reach near 12N134W by early on Saturday, and to near 12N138W on Sunday. The pressure gradient is tightening between this low pressure and the subtropical ridge to the north with fresh northeast trades developing tonight, and combined seas building to 6 to 9 ft across the discussion waters roughly from 13N to 25N west of 130W through Sunday. $$ CHRISTENSEN