000 AXPZ20 KNHC 082141 RRA TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Storm Warning: 1040 mb high pressure centered over eastern coastal Mexico extends a ridge southward toward the isthmus of Tehuantepec. The intense pressure gradient between this area of high pressure and lower pressure within the monsoon trough is supporting storm force winds over the Gulf of Tehuantepec with seas to 25 ft, based on recent ship reports and altimeter data. The high will shift eastward tonight, which will allow the pressure gradient to gradually relax over the region, with max winds diminishing below storm force early Monday. Gale force winds are expected to continue another day or so, through Tuesday night. A large area of large NE swell generated by this high wind event will spread far from its source region west to 110W, and south of the equator. Gulf of Papagayo Gale Warning: The pressure gradient associated with high pressure extending from the northwest Caribbean across interior Central America will tighten tonight, and winds in the Gulf of Papagayo region will increase to minimal gale force late tonight. Gales are expected to persist through early Monday then remain near gale through Tuesday morning. Northeast gap winds will be fresh to strong the remainder of the week. Seas will build to 11-13 ft Monday, and remain 9-12 ft downwind from the Gulf of Papagayo through Tuesday. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 04N77W to 05N103W. The ITCZ axis continues from 05N101W to low pressure near 09N131W to 07N140W. Scattered moderate convection is within 180 nm west of the coast of Colombia. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see special features section for more details on the Gulf of Tehuantepec high wind event. A weak pressure gradient prevails over much of the remaining forecast region. Light to gentle winds with 3-5 ft seas prevail in the waters off the coast of the Baja California peninsula and along the southwest coast of Mexico. Fresh northwest winds are indicated from scatterometer data over the central and southern Gulf of California. These winds are expected to diminish by this evening. Northwest swell will propagate into the waters offshore of Baja California Norte Wednesday night, increasing seas to 10 ft by early Thursday morning. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please see special features section for more details on the Gulf of Papagayo high wind event. The tight pressure gradient over Central America will support fresh to strong northeast winds offshore of Central America northwest of Nicaragua, including the Gulf of Fonseca, tonight through Tuesday. In the Gulf of Panama and near the Azuero Peninsula, northerly winds are expected to increase to 20 to 25 kt tonight through Tuesday as strong winds funnel into the area from the southwest Caribbean. Max seas will build to 9-10 ft south of the peninsula by early Tuesday. 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... 1011 mb low pressure area embedded in the ITCZ near 09N131W is moving west around 15 to 20 kt. Persistent deep convection is located within 200 nm of the low center. Previous scatterometer passes showed fresh to strong NE winds north of the low, and recent altimeter passes and a buoy near 10N125W measured 8-9 ft seas. This low will move west of 140W by late Monday night. A large occluded low pressure system north of the area extends a cold front through 30N129W to 19N138W. A weak ridge extends from 27N120W to near 19N132W. The pressure gradient between these two features is supporting fresh to strong S-SW winds north of 28N within 60 nm east of the front, with fresh westerly winds north of 28N west of the front to 140W. The front will move across the northern waters over the next couple of days, and dissipate with associated seas diminishing as well. The low pressure area well north of the area will continue to generate pulses of moderate to large northwest swell which will propagate into the northwest waters with seas building above 8 ft by Tuesday. The combination of swell generated from the Gulf of Papagayo and Gulf of Tehuantepec gap wind events will generate a large area of high seas that will eventually extend from the Tehuantepec and Papagayo regions southward to near the equator and westward to near 115W by Monday night. 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. $$ Mundell