000 AXPZ20 KNHC 151002 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 705 UTC Thu Dec 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec...A Gale Warning remains in effect for the Gulf of Tehuantepec from this evening to around midday Friday. North to northeast winds of 20 to 25 kt this morning will increase to between 30 and 35 kt this evening while highest seas build from around 8 ft to around 10 ft. A frontal boundary that has entered the northern Gulf of Mexico is introducing reinforcing high pressure into the Gulf. This will increase the pressure gradient over the Isthmus of Tehuantepec and cause increasing gap wind flow across the Gulf of Tehuantepec. Seas will top out around 12 ft with this gap wind event. The ridge over the Gulf of Mexico is expected to shift quickly eastward on Friday and Friday night, allowing this latest event to wind down. 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 09N77W to 10N97W to 1011 mb low pressure near 09N101W. The ITCZ extends from 09N101.5W to 07N110W to 07N127W to 07N136W to beyond 07N140W. Scattered moderate and isolated strong convection is noted from 03N to 08N between 77W and 81W, from 08N to 11N between 97W and 104W and within 60 nm either side of a line from 07N115W to 12N123W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: see Special Features section above for details. Gentle to moderate northerly winds and seas of 4-5 ft continue over the offshore waters W of Baja California this morning, under the influence of a weakening ridge extending southward from 1020 mb high pressure centered near 30N120W. The high and ridge will continue weakening during the next couple of days as a cold front moves eastward toward the Baja peninsula. The front, currently stalled across the far NW portion of the discussion area, is forecast to begin moving eastward this morning and reach northern Baja California and the northern part of the Gulf of California by Friday evening. Expect increasing winds ahead of this front over the Gulf of California and behind this front on both sides of the Baja peninsula. Model guidance suggests strong southwest winds ahead of the front and strong to near-gale force northwest winds behind the front over the northern Gulf of California Friday night and Saturday morning. Fresh to strong NW winds will affect the offshore zones N of 24N Friday evening through Saturday evening, with seas building to between 8 and 9 ft in the vicinity of the front N of 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 through early next week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A 1011 mb low is currently centered southwest of the Gulf of Tehuantepec near 09N100W. The low will continue weakening as it moves westward away from the offshore waters. The low is expected to become a trough by tonight. Scattered moderate and isolated strong convection is associated with this low from 08N to 11N between 97W and 104W. The areal coverage and extent of this convection should decrease as the low weakens. Fresh to strong NE winds will affect the Gulf of Papagayo E of 87.5W this morning and again on Friday morning. Seas should remain below 8 ft due to the limited fetch length. 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 frontal boundary has stalled over the NW waters from 30N136W to 27N140W. Winds in the vicinity of the front in this area are less than 20 kt. Seas behind the front N of 29N and W of 138W are running 8-10 ft. A reinforcing surge of cold air will begin pushing the front eastward across the N waters this morning. The front will reach Baja California Norte by Friday evening. Winds will remain 20 kt or less ahead of the front as it moves eastward, but will increase to 20-25 kt behind the front N of 27N W of 137W Friday night and Saturday morning as a strong high pressure builds over 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 today through Friday. NW to N swell will cause seas to build to 8-9 ft N of 25N W of 125W Friday night and Saturday, then seas in this area will subside. High pressure building in behind the cold front will bring increasing trade winds and building seas to the west-central waters during the upcoming weekend. A large area of fresh to strong trades will develop N of the ITCZ from 07N to 25N W of 125W by Tuesday morning. Seas in this area will build to between 9 and 13 feet. $$ cam