000 AXPZ20 KNHC 170232 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Fri Mar 17 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 0000 UTC surface analysis and satellite imagery through 0200 UTC. ...SPECIAL FEATURES... A Gale Warning remains in effect for the Gulf of Tehuantepec. 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 30-35 kt through the Gulf of Tehuantepec, with fresh to strong northerly winds extending downwind to near 12N98W. The most recent scatterometer pass confirmed the presence of these winds. 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 Saturday night through Sunday night. 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 108W 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 trough axis extends from 04N90W to 01N98W. Scattered moderate isolated strong convection is noted within 120 nm SE of trough between 90W and 94W. Scattered moderate convection is from 04N to 07N between 88W and 91W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features section for information on the Gulf of Tehuantepec gale warning. A high pressure located well north of the forecast area extends a 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... 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 tonight into Friday morning. Winds will reach 25-30 kt in and downwind of the Gulf of Papagayo, particularly from 09.5N to 11.5N east of 88W, with seas building to 8-10 ft. Winds of 20-25 kt and seas of 8-9 ft are also expected in a large area within about 120 nm either side of a line from 11N86W to 09N91W. The gap wind event in the Gulf of Papagayo will persist through Monday. 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 Saturday 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 high pressure located well north of the forecast area extends a ridge across the north waters, mainly north of 17N west of 110W. A new high pressure center is forecast to develop along the ridge axis near 30N126W on Friday, and will shift SE ahead of a cold front approaching from the west. Fresh to strong southerly flow is expected ahead of the front late tonight into Friday, with the front entering the forecast region early Friday afternoon. This front will reach from 30N135W to beyond 26N140W Friday night, and from 30N132W to 25N140W on Saturday, then stall late Saturday into Sunday. Seas to 8-9 ft are expected on either side of the front over the forecast waters on Friday. A second push of cold air will move the front to a position from 30N130W to 22N140W by early Monday morning, with another cold front reaching the forecast waters. Fresh to strong winds are expected on either side of the second front, forecast to extend from 30N138W to 28N140W on early Monday morning. 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 Saturday night as fresh swells generated by central American gap wind events propagate westward. $$ GR