000 AXPZ20 KNHC 042149 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2023 UTC Wed Jan 4 2017 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 2145 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 06N77W to 06N97W. The intertropical convergence zone axis extends from 06N97W to 08N110W to 10N132W to 08N140W. Scattered moderate convection is from 04N to 06N Between 86W and 89W to the south of the monsoon trough. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A weak 1021 mb high pressure is centered west of Baja California Norte near 28N120W, and is helping to produce gentle to moderate northerly winds across the Pacific waters off the coast of Baja California tonight. Seas in the 3 of 5 ft range prevail over this area. The pressure gradient will tighten slightly offshore of Baja California Sur through the end of the week, allowing for northwest flow to increase to moderate to fresh, then diminishing this weekend as the gradient relaxes to the west of the peninsula. In the Gulf of California, a locally tight pressure gradient is supporting fresh northwest winds of 20 KT flow from 23N to 28N as measured by a 1730 UTC ASCAT scatterometer pass. Seas are 4 to 6 ft in this area. The gradient will relax in the gulf late tonight, then will tighten more significantly this weekend with northwest flow increasing to fresh to strong south of 27N, which will build seas to 5 to 7 ft. In the Gulf of Tehuantepec, northerly winds will continue to pulse to fresh to strong mainly during the overnight into the early morning hours into early Thursday, with seas up to 7 ft. Light southerly flow will then prevail late Thursday through Friday evening with seas of 2 to 3 ft. A strong cold front will move through the Gulf of Mexico to the north of the area Friday through Saturday. Winds will become northerly and rapidly increase to 20 to 30 kt in the Gulf of Tehuantepec by early Saturday morning, then increasing to gale force by mid-day. Model guidance continues to indicate winds increasing to storm force by early Sunday morning, continuing into early next week. The potential exists for the strongest gap wind thus far this cold season in the area. Wave model guidance propagates a very large area of high seas well away from the source region, with significant wave heights in the Tehuantepec area building to at least around 25 ft by late in the weekend. Elsewhere between Cabo Corrientes and the Tehuantepec region, light to gentle breezes and seas in the 3 to 5 ft range, primarily in northwest swell, will prevail over the next several days. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... In the Gulf of Papagayo, winds will pulse to fresh to strong during the overnight into the early morning hours Thursday, then to moderate to fresh thereafter through early Saturday. Offshore flow will then increase back to fresh to strong Saturday night, with winds approaching near gale force by Sunday into early next week as strong high pressure ridging dominates across interior Central America in the wake of the Gulf of Mexico cold front. In the Gulf of Panama, nocturnal northerly flow will continue to pulse to fresh during the next few nights, increasing to fresh to strong early next week due to the strong high pressure ridging. These gap winds, along with a possible storm force event in the Gulf of Tehuantepec, will generate a very large area of high seas that will eventually extend from Tehuantepec to Papagayo to just northwest of the Galapagos Islands, spreading westward to 110W by early Tuesday. Elsewhere, light to moderate south to southwest winds will prevail south of the monsoon trough region, with seas 5 ft or less through the end of the week and the upcoming weekend. REMAINDER OF THE AREA... A weak to modest pressure gradient prevails elsewhere over the forecast waters. Fresh trade winds prevail south of the high between 110W and 130W, between the ITCZ and about 15N. Combined seas are generally running between 6 to 9 ft across this zone. Across the far northwest waters, a weak 1014 mb surface low near 26N136W with a surface trough extending to 28N133W then southward to 21N137W. The low is expected to dissipate within the next 12 hours. Meanwhile a weak cold front was entering the far NW portion of the area. An area of 8 to 9 ft seas in mixed southeast and northwest swell is present across this area between the low and front. The cold front will gradually dissipate with a remnant boundary found from 30N135W to 27N140W by 24 to 48 hours. Even with the features dissipating, associated mainly northwest swell of 8 to 11 ft will continue to propagate to the south and southeast, gradually mixing with the fresh trade wind seas to the south through the end of the week. The next frontal system and associated increasing winds and seas may approach the northwest portion of the discussion area this weekend. $$ COBB