000 AXPZ20 KNHC 051435 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1259 UTC Fri Jan 5 2018 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. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: The pressure gradient between high pressure along eastern Mexico and a surface trough over the eastern north Pacific is supporting gale force winds over the Gulf of Tehuantepec. The gale force winds are expected to continue into Sunday, before diminishing below gale force late Sunday. Swell generated from the persistent gale force winds will propagate downstream of the Gulf of Tehuantepec, with seas 8 ft or greater reaching as far south as 05N and west to 110W by tonight. Please refer to the latest high seas forecast issued under AWIPS/WMO headers HSFEP2/FZPN03 for more details. An earlier scatterometer satellite pass indicated strong to near gale force winds around a 1012 mb low pressure system near 22N130W. The low will deepen as it drifts northeast over the next couple days. The pressure gradient between the deepening low pressure area and high pressure to the west of the forecast waters will support gale force winds west of the low pressure center. Gale force winds are expected to develop by tonight, and last into the first half of the weekend. The low will lift north of the area Monday. Seas are forecast to build to 12-15 ft within the area of gale force winds. Please refer to the latest high seas forecast issued under AWIPS/WMO headers HSFEP2/FZPN03 for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 1009 mb low pressure near 06N79W to 05N95W. The intertropical convergence zone continues from 05N95W to 08N120W, and from 1010 mb low pressure near 08N135W to beyond 08N140W. Scattered moderate convection is noted form 06N to 08N between 82W and 84W, off the coast of Costa Rica. Scattered moderate convection is also ongoing form 10N to 12N between 122W and 125W. Scattered moderate convection is noted from 17N to 19N between 125W and 130W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see Special Features section above for more details about the ongoing gale force wind event in the Gulf of Tehuantepec. Looking ahead another gale force gap wind event is possible in the Gulf of Tehuantepec early next week as high pressure builds behind the next cold front forecast to move into the Gulf of Mexico. NW swell will propagate into the offshore waters off Baja California Norte Tuesday, with seas building to near 14 ft by Tue night. Elsewhere, relatively tranquil marine conditions are expected during the period. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Winds will pulse to near gale force over the Gulf of Papagayo tonight and Sat night before diminishing Sun. Light to gentle NE-E winds will prevail elsewhere to the N of 09N, with gentle to moderate S to SW winds expected S of 09N. REMAINDER OF THE AREA... Please see Special Features section above for details about the forecast gale center over the NW waters. A 1010 mb surface low persists near 10N134W, supported in part by upper divergence aloft between an upper trough along 135W and anticyclonic flow farther south. While there is related convection ongoing from 17N to 19N between 125W and 130W, there are no substantial areas of strong winds outside of convection, largely due to the 1012 mb low pressure centered north of the region. The surface low near 10N134W will likely dissipate through Saturday although a surface trough will remain in the area through early next week. An earlier altimeter pass indicated seas of 8 to 10 ft likely in NW swell over the area from 10N to 20N west of 135W. This will subside through early next week, ahead of another round of NW swell 8 ft or greater expected by mid week. $$ Christensen