000 AXPZ20 KNHC 050227 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Wed Apr 05 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 0315 UTC. ...SPECIAL FEATURE... GULF OF TEHUANTEPEC GALE WARNING... A cold front will sweep se across the Gulf of Mexico on Wed resulting in strong n winds developing in the Gulf of Tehuantpec on Wed evening. These n winds will quickly increase to minimal gale force at sunrise on Thu. The northerly winds will continue to strengthen throughout Thu with 30 to 40 kt winds, and seas to 15 ft, expected just downstream of the Gulf of Tehuantpec on Thu night. These winds will diminish to just below gale force briefly late Fri morning, but increase again to minimal gale force on Fri evening and then continue through late Fri night. Only fresh n winds forecast at sunrise on Sun. The resultant ne swell, in the form of 8 ft seas or greater, will propagate sw to along 08N between 97W and 104W on Fri night before beginning to subside. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A 1006 mb surface low is over nw Colombia at 09N74W with a surface trough extending sw along 07N78W to 04N97W where scatterometer winds indicate that the ITCZ forms and continues sw to 02N114W, then turns nw through another surface trough at 06N123W, then turns sw to beyond 02N140W. Scattered moderate isolated strong convection is observed along the eastern trough within 150 nm either side of a line from 07N84W to 03N97W. similar convection is noted over and the n of the the ITCZ within 120 nm of 03N123W and 09N132W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See special features above for the Gulf of Tehuantepec area. A surface ridge extends se along 22N116W to 10N93W. Gentle to moderate nw to n flow is expected through Wed morning across the offshore waters w of 102W. The pressure gradient will relax some on Wed night mainly across the outer waters, but expect a w to nw 15 to 20 kt wind shift near 26N113W late Wed night. Gulf of California: Gentle to moderate nw winds expected through Thu, except becoming fresh across the central gulf waters on Wed night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh drainage winds expected tonight. A narrow swath of strong ene winds is forecast on Wed night, with a more significant event on Thu, Fri and Sat nights. The resultant ne swell will propagate wsw to near 08N92W on Sat. Gulf of Panama: Moderate to fresh nocturnal flow expected during the overnight hours this week. Light to gentle winds, and combined seas of 3 to 5 ft, are occurring elsewhere outside of the swells originating near the gap events. REMAINDER OF THE AREA... Fresh ne trades expected across the tropics from 05N to 13N w of 110W this week. Mixing nw and n swell results in seas of 7 to 10 ft across the open waters n of 04N between 108W and 127W, but these seas should subside below 8 ft on Wed. Southwesterly winds are increasing to a strong breeze across the far nw waters to the n of 30N w of 137W in response to an approaching cold front expected to reach a position from 32N135W to 30N140W on Wed morning. The front will begin to weaken from 32N130W to 26N140W on Thu. By then a stronger cold front will reach near 32N140W preceded by a strong sw to w to nw wind shift and maximum seas of 15 ft along 32N. This second front will begin to weaken on Thu night as a third cold front enters the nw waters accompanied by a strong to near gale force wind shift, with maximum seas of 17 ft along 32N. $$ Nelson