000 AXPZ20 KNHC 050345 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Sat May 05 2018 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 0345 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec: Fresh to locally strong northerly winds will gradually increase to strong to near gale force on Sat evening with these conditions continuing through Sun. The northerly drainage flow is forecast to increase to minimal gale force on Sun night with seas building to 12 ft downstream near 15N 95.5W. The pressure gradient will relax on Mon with near gale winds continuing through sunrise on Tue. The gap event should end by late Wed morning. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends west-southwest from the Pacific coast of Colombia at 07N77W to 05N94W, then turns northwest to an embedded surface trough at 07N107W. Scatterometer winds indicate that an ITCZ develops at 08n110W and extends west-northwest to beyond 09N140W. Scattered moderate isolated strong convection is observed within 240 nm either side of a line from 06N80W to 05N95W, and within 240 nm of 11.5N109W. Isolated moderate convection is noted within 540 nm of 11N123W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Refer to special features section for the Gulf of Tehuantepec. A northwest to southeast ridge just seaward of 250 nm will shift east to a position from 22N116W to 17N104W on Sun where it will meander through the middle of next week. Moderate northwest flow forecast through late Sat west of the Baja Peninsula. The pressure gradient will tighten late Sat resulting in fresh to locally strong northwest flow between 30N and 32N along Baja Norte throughout Sat night. Mostly fresh northwest flow expected by midday Sun, diminishing to a moderate northwest breeze on Mon, with little change then expected through the middle of next week. Long period northwest swell, in the form of 8 to 9 ft seas, will move south into the waters north of 30N east of 122w on Wed, and propagate as far south as 27N on Thu before beginning to subside from the south. Gulf of California: Moderate northwest flow will continue across the gulf waters north of 30N through Sat afternoon, and moderate to locally fresh northwest flow will continue across the gulf waters south of 25N through Sat evening. Then light, mostly southerly flow forecast through the middle of next week except moderate nocturnal drainage flow near gap areas. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Moderate to locally fresh nocturnal winds are expected through the middle of next week. Gulf of Panama: Gentle northerly nocturnal flow is forecast through the middle of next week. REMAINDER OF THE AREA... A surface high is centered near 32N127W with a ridge extending southwest to beyond 25N140W. The high will shift southeast on Sat allowing a cold front to reach a position from 32N134W to 29N140W late Sat where it will stall. Fresh southerly flow will precede the front across the discussion waters north of 30N through early Sat. The cold front will dissipate by late Sun as a ridge redevelops from 32N129W to 24N140W. Strong southerly flow will develop north of this ridge on Sun ahead of a second cold front that will reach from 32N137W to 28N140W early Mon accompanied by strong southerly flow that will extend south to along 29N. Although the front will stall and wash out from 32N130W to 24N140W by late Tue, large seas of 10 to 15 ft are expected west of the front on Mon, but then quickly subsiding to 6 to 9 ft west of a line from 32N125W to 13N140W on Tue night. Model guidance is hinting that a tropical low will develop near 11N115W during the middle of next week and intensify as it tracks northwest. $$ Nelson