000 AXPZ20 KNHC 151612 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Sat Apr 15 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 1545 UTC. ...Special Features... A strong cold front is fast approaching the far northwest corner of the area. Ahead of the front the pressure gradient has tightened and strong south to southwest are occurring west of a line from near 32N135W to 27N140W, with seas of 8 to 10 ft. The cold front is forecast to reach from near 32N138W to 28N140W by early this afternoon with strong to near gale force winds expected north of 27N and east of the front to a line from near 32N132W to 27N137W. Southerly minimal gale force winds are expected along and north of 32N this afternoon and evening where seas will be higher, in the 10 to 12 ft range. These conditions will diminish late tonight as the cold front approaches a position from near 32N132W to 27n137W, and becomes stationary to 27N140W. At that time, southerly winds ahead of the front south of 32N will diminish to 20 to 25 kt within about 270 nm east of the front. The front is forecast to begin to weaken as it reaches from near 32N132W to 27N136W and stationary to near 27N140W early on Sunday, and dissipate by Sunday evening, with winds diminishing to the fresh range, and seas lower to 6 to 7 ft. Moderate to fresh northwest winds will initially follow the front into the northwest corner of the area today, but diminish to moderate to fresh northwest winds tonight. Seas of 8 to 9 ft in northwest swell will follow in behind the front, then subside to less than 8 ft on Sunday evening. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The northern Intertropical Convergence Zone axis extends from 04N93W to 03N118W to 03N130W to 03N140W. Scattered moderate/isolated strong convection is within 60 nm either side of the axis between 96W and 104W, and within 120 nm north of the axis between 125W and 128W. The southern Intertropical Convergence Zone axis extends from 03.4SN90W to 03.4S105W to beyond 03S120W. Scattered moderate to strong convection is within 30 nm of axis between 90W and 93W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... The pressure gradient between high pressure over eastern Mexico and lower pressures south of the Tehuantepec region is presently inducing strong northerly winds across the Gulf of Tehuantepec. These winds will diminish to the fresh range this afternoon, then pulse back up to strong winds late tonight into early Sunday aided by nocturnal drainage flow. The high pressure will shift eastward as low pressure develops over the Southern plains on Sunday, allowing the pressure gradient to slacken on Sunday afternoon, at which time the northerly winds become light to gentle southwest to west winds. Seas presently up to 9 ft will then subside to 5 to 6 ft and to 4 to 5 ft on Monday. The pressure gradient along the west coast of the Baja California Peninsula is loosening up, and the recent strong northwest along and offshore the peninsula have diminished to fresh category. These winds will diminish further to the moderate range this afternoon, and remain at generally the moderate range with possible brief episodes of fresh winds through Monday. Seas of 7 to 9 ft offshore Baja California Norte will subside to 6 to 7 ft on Sunday. The pressure gradient associated with high pressure building in behind a cold front that will dissipate to the west of the Baja California Peninsula will begin to induce fresh to strong northwest winds along the extreme northern section of the Baja California Norte Peninsula beginning late Monday night. Seas start to build to 6 to 8 ft with these winds, then gradually continue to build thereafter. Light and variable winds and seas generally below 2 ft will prevail across most of the Gulf of California through Monday as the pressure gradient remains loose along the Baja California Peninsula. Seas of about 3 to 4 ft are expected near the entrance of the Gulf through Monday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... In the Gulf of Papagayo, present fresh to locally strong nocturnal northeast to east drainage flow is expected to diminish to fresh category this afternoon and increase back to strong winds tonight and diminish to fresh category Sunday afternoon and remain at fresh intensity through Monday. Seas are expected to reach the range of 6 to 8 ft tonight before lowering to less than 8 ft this afternoon. In the Gulf of Panama, moderate to fresh northerly flow will diminish to mostly moderate winds this afternoon, then briefly to fresh to strong tonight before diminishing to moderate to fresh Sunday morning and to gentle to moderate Sunday afternoon. Seas will be 5 to 6 ft downstream of the Gulf. Elsewhere, light to gentle winds and combined seas of 4 to 6 ft will prevail through into early next week. REMAINDER OF THE AREA... See Special Features above for more details on gale conditions associated with the next cold front to move into the northwest portion of the area by early this afternoon. A set of northwest swell producing seas of 8 to 10 ft in the far northeast portion of the area will gradually decay through Sunday, with seas lowering to 6 to 7 ft there. A 1024 mb high pressure centered well north of area near 40N127W ridges S to 29N127W, then southeastward to near the Revillagigedo Islands. The pressure gradient between the ridge and lower pressures in the vicinity of the ITCZ is generating moderate to fresh NE winds roughly from 06N to 18N west of 137W, and from 06N to 22N between 119W and 137W. Associated seas are between 8 and 9 ft in mixed northwest swell and northeast wind waves. The high pressure will be displaced eastward as it weakens due to the approaching cold front. As a result, the trades over the central and western portions of the forecast area will weaken through Monday. Wave model guidance indicates that seas within this area of trades will subside below on Monday. Another cold front will move across the far northwest waters on Monday followed by strong northwest winds and seas to 9 ft. $$ Aguirre