000 AXPZ20 KNHC 071604 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1335 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... A storm warning is in effect for the Gulf of Tehuantepec. This event promises to be the strongest so far this season. A cold front has pushed southward along the western shore of the Gulf of Mexico to the Isthmus of Tehuantepec. Very strong high pressure is nosing southward over the western Gulf in the wake of the front. High pressure is expected to build to 1043 mb over south Texas today. The associated ridge will continue to extend southward along the Gulf coast of eastern Mexico through the weekend. The pressure gradient between this high pressure system and lower pressure within the equatorial trough over the eastern north Pacific will bring storm force winds to the Gulf of Tehuantepec region. Minimal gale force north winds will further increase to storm force early this afternoon, with seas building to 12-20 ft. Winds will further increase to 45-55 kt with possible higher gusts this evening with seas building to the 18-27 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 tonight through Sunday night. This will loosen the pressure gradient over the Tehuantepec region and will help winds diminish to below storm force Sunday night. The gale force winds are expected to continue across the Tehuantepec region through late Tuesday. The high pressure ridge over the gulf will continue to shift eastward Wednesday and Thursday and set up SE to S return flow over the Gulf. This will bring this latest Tehuantepec gap wind event to an end by Thursday evening. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 07N86W to a 1010 mb low pressure near 07N93W to 06N96W to 07N108W to 06N118W to 1010 mb low pressure near 08N123W to 08N126W. The ITCZ continues from 08N126W to 08N133W to beyond 07N140W. 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, 1021 mb high pressure centered near 30N119W is the primary weather player for the offshore waters west of the Baja California Peninsula. Gentle to moderate N to NE winds are noted with seas in the 3-5 ft range along the west coast of the Baja California peninsula. The pressure gradient between this area of high pressure and a surface trough over Mexico is generating 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 cause 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 12 ft. In the Gulf of Panama, fresh nocturnal northerly flow is expected through Sunday night. Winds will further increase to 20-25 kt Sunday night and 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 tightens 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 coalesce eventually extend from Tehuantepec and Papagayo regions southward to near the equator and westward to near 117W by Monday evening. The area of seas will shift westward and begin to decay on Tuesday and Wednesday. 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 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 satellite-derived sea height data show 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. $$ cam