000 AXPZ20 KNHC 072118 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Dec 7 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 2100 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: Light winds during the day will prevail through Thursday afternoon, with northerly winds at night in nocturnal drainage flow. strong high pressure building over southern Mexico Thursday night behind a cold front in the Gulf of Mexico will induce northerly winds in Tehuantepec waters to rapidly increase to gale force early Friday, then continue through Saturday night. Highest winds are expected to be 40 kt Friday night. Max seas will build to 16-18 ft downstream from the Tehuantepec coast. Gale force winds will diminish to 15-20 kt by early Sunday. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N85W to 08N97W to 10N107W to 10N115W. The ITCZ axis continues from 10N115W to 10N123W to 08N140W. Scattered moderate convection from 10N to 12N from 108W to 117W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of California: A surface trough extends over north-central waters from 31N114W to 25N109W. A weak cold front will slide southward across the region tonight, with winds shifting to N-NW behind the front. A tighter pressure gradient will allow winds to become fresh to strong in the central Gulf of California from 25N to 28N Thursday afternoon through Friday morning, with seas building to 5-7 ft. High pressure centered near 28N127W anchors a ridge west of Baja California. Gentle to moderate anticyclonic flow is expected through Friday. Combined seas in northwest swell of 4 to 7 ft will subside from northwest to southeast today. Offshore winds north of 28N will become fresh to strong this weekend as the gradient tightens, with seas building to 7-9 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Moderate to locally fresh nocturnal east- northeast winds are expected the next couple of nights, becoming fresh to strong Friday night and Saturday night as the gradient across the region tightens. Max seas will build to 7-8 ft downwind of the gulf region. Light to gentle northerly winds and combined seas of 2 to 4 ft are occurring elsewhere north of the monsoon trough near 10N. Light to moderate southwest flow is observed south of 10N, with combined seas of 3 to 5 ft in long period southwest swell. REMAINDER OF THE AREA... High pressure centered near 28N127W anchors a ridge along 27N west of 115W. The high will drift eastward through Friday. A cold front is expected to stall over the far northwest waters Thursday, then weaken and drift westward Thursday night. Gentle to moderate northwest to north flow is expected northeast of the ridge through Thursday. Moderate to fresh east-northeast trades will prevail south of the ridge, with highest winds just north of the ITCZ. 5-7 ft seas in the deep tropics will build to 7-9 ft this weekend near the convergence zone west of 125W. $$ Mundell