000 AXPZ20 KNHC 120924 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 924 UTC Wed Apr 12 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 0900 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning...The pressure gradient between high pressure ridging surging down eastern Mexico and lower pressures just SE of the area is supporting developing fresh to strong northerly flow in the Gulf of Tehuantepec which will quickly increase to minimal gale force in the next few hours. These conditions will diminish below gale force by the afternoon, then will return late tonight into early Thursday. Seas will build to up to 12 ft once the gale force winds begin. The pressure gradient will relax on Thursday afternoon with fresh to strong northerly flow pulsing thereafter through the remainder of the week and the upcoming weekend, mainly at night with nocturnal drainage flow. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The intertropical convergence zone axis extends from 05N102W to 03N116W to 04N130W where it is disrupted by an embedded surface trough, then resumes from 02N137W to 04N140W. Widely scattered moderate convection is within 240 nm north of the ITCZ between 115W and 130W. In addition, scattered moderate and isolated strong convection is from 04N to 06N between 88.5W and 90.5W to the east of a mid to upper level trough. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the special features section for details on the Gulf of Tehuantepec gale warning. A surface ridge extends from northwest to southeast across the offshore waters. Moderate to fresh anticyclonic winds prevail along the Pacific coast of Baja with long period northwest swell contributing to combined seas of 6 to 9 ft. The pressure gradient will tighten through the day and into tonight, increasing winds to fresh to strong by late tonight into early Thursday. These winds will persist through Friday night. The increasing winds will support seas of 7 to 9 ft across the offshore waters W of the Baja California Peninsula. In the Gulf of California, light to gentle variable flow will then prevail through the week and into the upcoming weekend with seas mainly 2 ft or less, except 3 to 4 ft near the entrance to the Gulf. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... In the Gulf of Papagayo, fresh to locally strong nocturnal drainage winds are expected to pulse through the week and the upcoming weekend. The most significant winds are expected late tonight when they may briefly approach 30 kt. Seas will build to near 7 ft downstream of the gulf waters during and shortly after the pulsing conditions. In the Gulf of Panama, moderate to fresh nocturnal northerly flow is expected during the overnight hours through the remainder of the week and the upcoming weekend. Seas are expected to build to a range of 5 to 7 ft downstream of the gulf waters. Elsewhere, light to gentle winds and combined seas of 3 to 6 ft will prevail during the next several days. REMAINDER OF THE AREA... A cold front extends into the NW and N central waters from 30N129W to 28N133W to 26N140W. The front is weakening with gentle to moderate winds both ahead of and behind it. The front will continue to weaken and slow down as it progresses eastward through tonight. Associated NW swell to 8 ft will subside through the morning as the front weakens. A new front will quickly approach and invade the waters SE of 30N140W tonight with a set of 8 to 11 ft NW swell behind it. The two boundaries will eventually merge by late Thursday night with the remnant front dissipating through the day Friday. Elsewhere, a ridge extends from 1021 mb high centered near 26N130W SE to near 13N105W. An area of fresh to strong trades over the W central waters was recently sampled by scatterometer passes with surrounding moderate to fresh trades SW of the ridge axis. Combined seas of 8 to 10 ft prevail in fresh NE swell and long period NW swell. Similar conditions will prevail through the remainder of the week, with trades weakening slightly this weekend as the pressure gradient weakens. The gradient will weaken due to a stronger cold front which will approach 30N140W by early Saturday, entering Saturday night with fresh to strong southerly flow ahead of it. $$ LEWITSKY