000 AXPZ20 KNHC 142204 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Dec 14 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 2130 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec...A Gale Warning is in effect for the Gulf of Tehuantepec beginning Thursday evening. This afternoon, northerly winds in the 20-25 kt range are noted across the Gulf, with seas of 5-7 ft. Winds will further increase to 30 kt tonight, with seas building to 8 ft in and downstream of the Gulf. A cold front moving across the Gulf of Mexico on Thursday will allow northerly winds behind the front to begin to spill through the Isthmus of Tehuantepec and across the Gulf of Tehuantepec. Winds across these Pacific waters are forecast to reach minimal gale force Thursday evening through Friday morning, while seas are forecast to build to 9-11 ft with this gap wind event. A stronger cold front could produce a more significant northerly gale wind event beginning on Monday. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 06N76W to low pressure near 09N98W to 07.5N101W. The ITCZ extends from 07.5N101W to 10N127W to 13N140W. Scattered moderate to strong convection is noted within 150 nm N of the ITCZ between 117W and 125W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: please, see Special Features section for details. Gentle to moderate northerly winds and seas of 4-5 ft are noted over the offshore waters W of Baja California this afternoon, under the influence of a ridge anchored by a 1021 mb high pressure center located near 31N122W. The high will weaken over the next couple of days as a cold front moves eastward across the N waters. The front, currently entering the far NW portion of the discussion area, is forecast to approach northern Baja California on Friday and move into the area...including the northern part of the Gulf of California by Friday night. Expect increasing winds ahead and behind this front. Model guidance suggests strong southwest to west winds ahead of the front and strong to near-gale force west to northwest winds behind the front over the northern Gulf of California Friday night into Saturday morning. Fresh to strong NW winds will affect the offshore zones N of 25N on Saturday and N of 22N Saturday evening, with seas building as high as 10 ft near 30N. Outside of the Gulf of Tehuantepec area, mainly light to gentle winds prevail south of Cabo Corrientes, with seas of 3-4 ft. These marine conditions will persist over the next couple of days. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A 1010 mb low pressure center, currently centered southwest of Tehuantepec near 09N98W, will continue to move westward and away from the offshore waters while opening up into a trough by Thursday. Widely scattered moderate to strong convection is noted within 120 nm of the low, and from 10.5N to 14N between 92.5W and 99.5W. This active weather should continue through the evening hours. Fresh to strong NE winds and building seas to near 8 ft are expected across the Gulf of Papagayo E of 89W beginning late tonight through early Thursday morning, then persisting through Friday morning. A larger gap wind event appears to be in store for most of zone PMZ113 on Tuesday morning as strong trade wind flow in the SW Caribbean funnels across Central America. REMAINDER OF THE AREA... A cold front has already reached the NW waters and extends from 30N138W to 26N140W. Fresh to strong S-SW winds are observed north of 25N and within 210 nm east of the front, where seas are running 8-9 ft. The front will continue to move across the N waters, reaching Baja California Norte by Friday night. Winds are forecast to diminish to 20 kt or less ahead of the front by Thursday night, and winds will increase again ahead and behind the front Friday night into Saturday morning as a strong high pressure builds across the forecast waters in the wake of the front. N swell generated behind the front will cause seas to build to 8-10 feet across the far NW waters tonight into Thursday. 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. High pressure building N of the area will cause a large area of fresh to strong trades to develop N of the ITCZ from 07N to 25N W of 125W by Tuesday morning. Seas in this area will be build to the 8 to 11 foot range. As previously mentioned, a 1021 mb high pressure is centered near 31N122W and extends a ridge across the NE waters. The pressure gradient between the ridge and a newly developed surface low near 18.5N133.5W is producing an area of fresh to strong E to S winds within 180 nm across the eastern semicircle of the low. The low will shift north northeastward over the next 24 hours, ahead of the approaching cold front across the NW waters, and weaken to an open trough, gradually merging with the southerly winds occurring east of the front. Expect increasing trade winds and building seas across the west- central waters during the upcoming weekend as strong high pressure builds N of area. $$ Stripling