000 AXPZ20 KNHC 081517 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1517 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Storm Warning: A 1040 mb high pressure center over eastern coastal Mexico is extending a ridge southward toward the Tehuantepec area. 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 and tonight, which will gradually loosen the pressure gradient over the Tehuantepec region and will help winds diminish to below storm force by late tonight into early Monday. Although winds will decrease below storm force, the gale force winds are expected to continue across the Tehuantepec region through Tuesday night. Gulf of Papagayo Gale Warning: A 1027 mb high pressure center over northern Guatemala extends a ridge to the southeast across interior Central America. The pressure gradient between this area of high pressure and lower pressure within the monsoon trough south of Central America will tighten tonight, and pre-existing fresh to strong northeast flow offshore in the Gulf of Papagayo will increase to minimal gale force by late tonight. Gale force winds are expected to persist through Monday morning before diminishing to near gale which will continue through Tuesday morning. Winds will be fresh to strong thereafter for the remainder of the week. Seas will build to 11 to 13 ft downwind of the Gulf of Papagayo through the early part of the week. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from low pressure near 09N75W to 08N85W to low pressure near 06N97W to 04N101W. The intertropical convergence zone axis extends from 04N101W to low pressure near 09N129W to 08N140W. Scattered moderate to strong convection is within 150 nm west of the coast of Colombia. ...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 to 5 ft range prevails over the waters off the coast of the Baja California peninsula and also along the southwest coast of Mexico. Fresh northwest winds are noted over the central and southern Gulf of California region. These winds are expected to diminish by late afternoon. 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... Please see above for more details on the Gulf of Papagayo gale force gap wind event. The same tight pressure gradient over Central America that is responsible for the upcoming gale event in the Gulf of Papagayo will produce fresh to strong northeast winds offshore of the remainder of Central America northwest of Nicaragua, including the Gulf of Fonseca, starting tonight through the early part of the week. In the Gulf of Panama and near and southwest-west of 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. Seas will build to up to 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... Low pressure of 1011 mb is embedded in the ITCZ near 09N129W and is moving west around 15 to 20 kt. Deep convection has developed during the past several hours within 210 nm in the north semicircle and 120 nm in the south semicircle. Overnight scatterometer passes showed fresh to strong winds on the north-northeast side of the low, while recent altimeter passes and a buoy near 10N125W measured 8 to 9 ft seas. This low will continue to move quickly to the west, eventually west of 140W by late Monday night. To the north, low pressure of 992 mb centered north of the area near 44N130W extends a cold front into the area through 30N131W to 20N140W. A surface ridge extends from weak 1021 mb high pressure southwest of Baja California Norte near 28.5N120W to the southwest just ahead of the front near 18N138W. The pressure gradient between these features is supporting fresh to strong winds north of 26N within 180 nm east of the front, with fresh to strong winds north of 28N between 133W and 137W where a reinforcing trough is located. The front will move across the northern waters over the next couple of days before dissipating with associated winds diminishing later today. The low pressure area well north of the area will continue to spin while deepening over the next several days. This will generate a northwesterly swell which will propagate into the northwest waters with seas building 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. $$ LEWITSKY