000 AXPZ20 KNHC 170853 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 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 0600 UTC surface analysis and satellite imagery through 0745 UTC. ...SPECIAL FEATURES... A Gale Warning remains in effect for the Gulf of Tehuantepec. A persistent ridge across the Gulf of Mexico and eastern Mexico sustains a tight pressure gradient across the Gulf of Tehuantepec, which support gale force winds of 30-35 kt with fresh to near-gale northerly winds extending downwind to near 13N. Minimal gale force winds are expected across the Tehuantepec region through Monday morning, except for a brief period of winds around 30 kt during the afternoon hours. 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 Gulf of Papagayo. This will result in combined seas of 8 ft or greater covering the waters from 06N to 12N between 96W and 107W early Sunday 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 06N88W to 03N96W. Scattered moderate isolated strong convection is noted from 02N to 07N between 87W and 96W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features section for information on the Gulf of Tehuantepec gap wind event. 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 in 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 supporting a strong gap wind event across the Gulfs of Papagayo and Fonseca through this morning. Winds will reach 25- 30 kt in and downwind of the Gulf of Papagayo, particularly from 09N to 12N east of 88W, with seas building to 8-9 ft. Winds of 20-25 kt and seas of 8-9 ft are also expected in a large area from 06N to 09N east of 102W. 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 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 16N west of 110W. A new high pressure center is forecast to develop along the ridge axis near 30N126W on Friday afternoon, and will shift SE ahead of a cold front approaching from the west. Fresh to strong southerly flow is ahead of the front and is expected to continue over far northwest forecast waters through Friday night mainly west of a line from 30N138W to 29N140W. This front is forecast to 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 23N138W by Monday morning. Fresh to strong winds are expected on either side of the second front, forecast to extend from 30N139W 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 through Saturday night as fresh swells generated by central American gap wind events propagate westward. $$ NR