000 AXPZ20 KNHC 131528 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Tue Dec 13 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 08N84W to 1010 mb low pressure near 09N92W to 08N108W. The ITCZ continues from 08N108W to 09N125W to 07N132W to 07N140W. Scattered moderate convection is from 04N to 07N between 77W and 80W. Scattered moderate convection is from 10N to 14N between 92W and 95W. Scattered moderate convection is within 90 NM either side of the axis between 97W and 130W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: Fresh to strong north winds continue north of 14.5N with seas to 7 ft. Residual high pressure over the SW Gulf of Mexico will maintain enough pressure gradient to produce fresh to strong N to NE winds primarily during the late night hours over the Gulf of Tehuantepec through Thursday night. A cold front crossing the northern Gulf of Mexico will reinforce high pressure over the SW gulf and strengthen the drainage winds over the gulf of Tehuantepec. Near gale force winds appear to be in the offing for Thursday evening through Friday as a result. A stronger cold front could produce a gale wind event beginning on Monday. Moderate northwest winds over the offshore waters north of 20N will become gentle to moderate through Thursday night with 3-5 ft seas. A cold front will extend from 31N116W to 22N129W around midday on Friday. The front will sweep southeastward across the Baja Peninsula and NW Mexico and pass south of the Baja Peninsula by Saturday evening. Model guidance shows strong southwest to west winds ahead of the front and strong to near-gale force west to northwest winds behind the front over the Gulf of California on Friday night. Fresh to strong NW winds will affect the offshore zones N of 25N on Saturday and Saturday night, with seas building as high as 11 ft near 30N. Gentle to moderate north to northwest winds will prevail south of Mazatlan through Wednesday, becoming light Thursday through Saturday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A weak surface low currently centered south of Guatemala near 09N92W will move westward away from the forecast zones through Thursday night. Global models indicate gradual filling of the low for the next several days. The low could weaken into a trough west of 100W by Thursday. Latest global model forecasts show winds of 20 to 25 kt in the north or northeast quadrants of the low during the next day or so. Winds will decrease as the low continues to weaken. REMAINDER OF THE AREA... Broad high pressure continues to reside over the northern waters. The high remains centered near 28N126W. Gentle to moderate north- northwest winds are expected east of the high through Wednesday. A trough of low pressure has developed from 10N132W to 15N131W. The tighter pressure gradient on the north side of the trough is generating NE to E winds of 20 to 25 kt and seas to 8 ft. The trough is expected to gradually weaken as it translates northwestward during the next couple of days, allowing the associated winds and seas to subside. Low pressure and a trailing frontal boundary are lurking west-northwest of the area. The front will enter the far NW waters Wed. South to southwest winds of 20 to 25 kt and 8-10 ft seas will precede the boundary. Reinforcing cold air will push the front east- southeastward across the northern waters Thursday and Friday. NW swell generated behind the front will cause seas north of 25N and west of 120W to build to 8-10 feet by Friday. Seas east of 130W will briefly subside to around 8 ft on Saturday before a round of reinforcing N swell arrives on Sunday. $$ Formosa