000 AXPZ20 KNHC 060915 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Sun May 06 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 0600 UTC surface analysis and satellite imagery through 0915 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec gale warning: Minimal gale force winds expected to last just past sunrise this morning, then diminish briefly to near gale force conditions this afternoon before increasing to minimal gale force again this evening, and then continuing at gale force through sunrise on Mon. Seas are forecast to build to 12 ft downstream of the gulf waters near 15N 95.5W. The pressure gradient will relax late Mon, with near gale winds then continuing through sunrise on Tue. The gap event should end by late Wed morning with winds diminished to 20 kt or less. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends west from the Pacific coast of Colombia at 07N78W to an embedded surface trough that extends north to south from 06N to 17N along 115W. Scatterometer winds indicate an ITCZ develops at 08N120W and extends west to beyond 08N140W. Scattered moderate isolated strong convection is observed within 210 nm either side of a line from 07N78W to 06N103W to 10N119W, and within 75 nm of 09N125W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Refer to special features section for a warning across and downstream of the Gulf of Tehuantepec. A northwest to southeast ridge extends about 250 nm seaward from near 21N116W to 13N99W. This ridge will meander along this position through Tue, then retract north-westward. Fresh northwest flow will continue across the waters 29N and 32N west of Baja Norte through this evening. Moderate northwest flow is then forecast through the middle of next week. Long period northwest swell, in the form of 8 to 12 ft seas, will move south into the waters north of 30N east of 122W on Wed, and propagate as far south as 26N on Thu before beginning to subside from the south. Gulf of California: Light, mostly southerly flow forecast through the middle of the week, except moderate nocturnal drainage flow expected 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 Mon night. Gulf of Panama: Gentle northerly nocturnal flow is forecast through the middle of the week. REMAINDER OF THE AREA... A surface high is centered near 29N131W with a ridge extending southwest to beyond 26N140W. The high will lift north-northeast and the ridge will shift southeast and weaken today allowing a weak cold front to reach a position from 32N134W to 29N140W this evening. Strong southerly flow, and 6 to 9 ft seas, will precede the front across the discussion waters north of 29N tonight. Although the front will stall and wash out from 32N131W to 24N140W by late Tue, large seas of 10 to 16 ft are expected west of the front on Mon, but these large seas will quickly subside to 6 to 9 ft west of a line from 32N128W to 16N140W on Tue night. The seas will further subside to less than 8 ft across the tropics during the middle of the week, but seas of 8 to 11 ft are forecast north of 26N east of 124W late in the week. Model guidance is hinting that a tropical low will develop within the monsoon trough near 10N120W during the middle of the week, and intensify as it tracks northwest late in week. $$ Nelson