000 AXPZ20 KNHC 161504 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1504 UTC Thu Mar 16 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 1445 UTC. ...SPECIAL FEATURES... GULF OF TEHUANTEPEC GALE WARNING: A persistent ridge across the Gulf of Mexico and along the Mexico coastal plains is maintaining a tight pressure gradient across southern Mexico and across the Gulf of Tehuantepec. This is supporting gale force winds of 30-40 kt through the Gulf of Tehuantepec, with fresh to strong northerly winds extending downwind to near 13N97W. Minimal gale force winds are expected across the Tehuantepec region through Monday, except for a brief period of winds around 30 kt Friday afternoon. Winds are likely to increase to 40 kt during the overnight and early morning hours through the weekend, with the assistance of the nocturnal drainage flow. Northerly swell generated by this gap wind event will propagate southward and mix with long-period southwest swell from the southern hemisphere, and NE swell generated in the Papagayo gap wind region, resulting in combined seas of 8 ft or greater covering the waters from 06N to 11N between 90W and 107W Friday morning through Saturday morning. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... There is no intertropical convergence zone or monsoon trough currently analyzed north of the equator east of 140W. A surface trough axis extends from 07N84W to 00N99W. Scattered moderate convection is within 90 nm northwest of the trough east of 93W, and also west of 95W. In addition, scattered moderate convection is from 10N to 12N between 120W and 123W. This area is under an area of upper level diffluence. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features section for information on the Gulf of Tehuantepec gale warning. A 1026 mb high pressure center is located near 32N132W and extends a weak ridge SE to near the Revillagigedo Islands. Gentle to locally moderate NW winds and seas generally under 5 ft are noted across the offshore waters of Baja California under the influence of the ridge. Gentle and variable winds and seas of 2 ft or less are inside the Gulf of California. These general marine conditions will persist through the upcoming weekend and early next week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to strong NE-E winds are expected across and downwind of the Gulf of Papagayo, particularly during the overnight and early morning hours through the remainder of the week and into the upcoming weekend. Seas will build to 8-9 ft during the strongest winds. Winds will reach 25-30 kt tonight through Saturday morning. Building high pressure across the NW Caribbean and Gulf of Mexico is forecast to induce a strong gap wind event across the Gulfs of Papagayo and Fonseca late Thursday night into early Friday morning. Fresh to strong northerly winds are also forecast across the Gulf of Panama and downwind to about 04N-05N at night. Seas will build to 5-7 ft in this area, including offshore of the Azuero Peninsula. These weather conditions will likely persist through Friday night. Otherwise, light to gentle winds and combined seas of 3-5 ft are expected to continue through the week and into the upcoming weekend. REMAINDER OF THE AREA... A 1026 mb surface high centered near 32N133W will remain nearly stationary over the next 24 hours. A frontal boundary is NW of the far NW corner of the area and will lift N of the area through tonight as another cold front approaches from the west. Fresh to strong southerly flow is expected ahead of the second front tonight into early Friday, with the front entering the forecast region early Friday afternoon. This front will reach from 30N136W to beyond 26N140W Friday night, and from 30N132W to 25N140W on Saturday, then stall late Saturday into Sunday. Seas to 8 ft are expected on either side of the front over the forecast waters. A second push of cold air will move the front to a position from 30N130W to 22N140W by early Monday morning with a secondary front extending from 30N135W to 27N140W. Otherwise, mainly moderate to locally fresh trades will persist elsewhere across the open tropical Pacific waters. Combined seas will be in the 5-7 ft range, but will build to 8-9 ft along and south of 10N roughly between 90W-110W Thursday night through late Saturday as fresh swells generated by central American gap wind events propagate westward. $$ LEWITSKY