000 AXPZ20 KNHC 080936 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 545 UTC Sun Jan 8 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. A 1043 mb high pressure center over eastern Texas is extending a ridge southward over eastern Mexico. The pressure gradient between this area of high pressure and lower pressure within the monsoon trough over the eastern north Pacific is supporting storm force winds over the Gulf of Tehuantepec with seas over 20 ft. The high pressure center will shift eastward today, which will loosen the pressure gradient over the Tehuantepec region and will help winds diminish to below storm force tonight. Although winds will decrease below storm force, 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 09N83W to a 1012 mb low pressure near 06N95W to 05N98W. The ITCZ continues from 05N98W to 1012 mb low pressure near 09N128W to beyond 09N140W. Scattered moderate isolated strong convection is noted from 08N to 10N between 127W and 132W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see above for more details on the Gulf of Tehuantepec storm force gap wind event. Elsewhere, a weak pressure gradient prevails over much of the forecast region. Light to gentle winds with seas in the 3-4 ft range prevails over the waters off the coast of the Baja California peninsula and also along the southwest coast of Mexico. Fresh to strong winds are noted over the central and southern Gulf of California region. These winds are expected to fall below advisory criteria by this evening. Winds and seas will remain below advisory criteria through midweek. Northwesterly swell will propagate into the waters offshore of Baja California Norte late Wednesday night into Thursday which will bring seas near 10 ft early Thursday morning. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Strong high pressure building behind the cold front responsible for the Gulf of Tehuantepec storm event has helped for strong northeast gap winds to develop across the Gulf Papagayo as depicted by the latest ASCAT pass. Winds will expand downstream from Papagayo as well as northward to include the Gulf of Fonseca by tonight. Winds are expected to reach near gale force in the Papagayo area late tonight into Monday with seas building up to 12 ft. A tight pressure gradient will continue over the area which will maintain an extended gap wind event over the Gulf of Papagayo through mid week. In the Gulf of Panama, winds are expected to increase to 20-25 kt tonight through Tuesday as strong winds funnel into the area from the southwest Caribbean. The combination of swell generated from the Gulf of Papagayo and Gulf of Tehuantepec gap wind events will generate a large area of 8 ft seas or greater that will eventually extend from the Tehuantepec and Papagayo regions southward to near the equator and westward to near 115W by Monday night. REMAINDER OF THE AREA... Low pressure of 995 mb centered north of the area near 42N132W extends a cold front just northwest of the area. A surface ridge extends from high pressure over the Great Basin region across southern California into the northeastern forecast waters. The pressure gradient between these features is supporting strong to near gale winds over the waters north of 27N between 128W and 133W as depicted by the most recent ASCAT pass. The front will move across the northern waters over the next couple of days before dissipating. High pressure building in the wake of the front will bring pressure rises over the northwestern waters today which will loosen the pressure gradient over the northern waters late tonight. Winds and seas will diminish below advisory criteria over this area. The low pressure area described above will continue to spin north of the area while deepening over the next several days. This will generate a northwesterly swell which will propagate into the northwest waters with seas rising above 8 ft by Tuesday. Elsewhere, gentle to moderate trades are forecast to prevail over most of the area under a weak pressure gradient through the middle of next week. $$ AL