000 AXPZ20 KNHC 070908 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 455 UTC Sat Jan 7 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURES... A storm warning is in effect for the Gulf of Tehuantepec. This upcoming event is forecast to be the strongest of the events so far this season. A cold front is moving across the Gulf of Mexico with very strong high pressure building in its wake. High pressure is expected to reach 1043 mb over north- central Texas today. The associated ridge will press southward along eastern Mexico through the weekend. The pressure gradient between this this area of high pressure and lower pressure within the equatorial trough over the eastern north Pacific will set up a tight pressure gradient over the Gulf of Tehuantepec region. Northerly winds will quickly increase to minimal gale force early this morning. Winds will further increase to storm force early this afternoon, with seas building to 10-15 ft. Winds will further increase to 45-55 kt with possible higher gusts on this evening with seas building to the 18-24 ft range. The gale force winds surrounding the storm force wind area will expand well to the south and southwest of the Isthmus of Tehuantepec through Sunday evening. The high pressure center will shift eastward through the weekend. This will loosen the pressure gradient over the Tehuantepec region and will help diminish winds below storm force late Sunday night. The gale force winds are expected to continue across the Tehuantepec region through late Tuesday. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 08N82W to a 1009 MB low pressure near 06N90W to 07N99W. The ITCZ continues from 07N99W to a 1009 mb low pressure near 06.5N113W to 1009 mb low pressure near 08N121W to 06N132W to beyond 08N140W. No significant convection. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see above for more details on the Gulf of Tehuantepec storm force gap wind event. Outside of the Gulf of Tehuantepec region, a ridge dominates the offshore waters west of the Baja California Peninsula. Gentle to moderate northerly winds are noted with seas in the 3-5 ft range off the west coast of the Baja California peninsula. The pressure gradient between this area of high pressure and a surface trough over Mexico is supporing fresh to strong winds over the central and southern Gulf of California region. The pressure gradient will loosen slightly this weekend as pressures rise over Mexico. This will bring winds below advisory criteria by Sunday evening. 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... The very strong high pressure building behind the cold front responsible for the Gulf of Tehuantepec storm event will help for strong northeast gap winds to develop across the Gulfs of Papagayo and Fonseca late tonight into Sunday. Winds are forecast to reach near gale force in the Papagayo area late Sunday night into Monday with seas building up to around 11 ft. In the Gulf of Panama, fresh nocturnal northerly flow is expected through Sunday night. Winds will further increase to 20-25 kt on Monday as strong winds funnel from the SW Caribbean into the Gulf of Panama as high pressure behind the cold front over the Caribbean waters helps tighten the pressure gradient. These gap wind events, along with the storm force wind event in the Gulf of Tehuantepec, will generate a large area of 8 ft seas or greater that will eventually extend from Tehuantepec and Papagayo regions southward to near 2N-3N and westward to near 111W by early Monday morning. Elsewhere, light to moderate south to southwest winds will prevail south of the monsoon trough region, with seas 5 ft or less through the upcoming weekend. REMAINDER OF THE AREA... A strong cold front will move into the northwest waters late tonight into Sunday. This front will be accompanied by with a large area of fresh to strong winds over much of the northwest and north- central waters. Winds will peak near gale force east of the front early Sunday with seas building to near 12 ft. The latest scatterometer pass depicts gentle to moderate trades north of the ITCZ to near 20N. The pressure gradient will remain weak over this area through the forecast period with winds and seas expected to remain below advisory criteria through at least Monday. $$ AL