000 AXPZ20 KNHC 060345 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 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: Model guidance suggests that the northerly drainage flow will reach minimal gale force tonight, and persist through sunrise on Sun, then diminish briefly to near gale force conditions on Sun afternoon before increasing to minimal gale force again on Sun 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 new to an embedded surface trough that extends north to south from 07N to 16N along 111W. The monsoon trough resumes west of the surface trough at 08N113W and continues west- southwest to 08N120W where scatterometer winds indicate a transition to an ITCZ that continues west to beyond 09N140W. Scattered moderate isolated strong convection is observed within 180 nm either side of a line from 06N80W to 07N100W to 10N119W, and within 90 nm either side of a line from 10N119W to 05N136W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Refer to special features section for a warning in 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 westward. Fresh northwest flow will continue across the waters 29N and 32N west of Baja Norte through Sun evening. Moderate northwest flow then forecast through the middle of next week. Long period northwest swell, in the form of 8 to 11 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 next 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 next 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 on Sun allowing a weak cold front to reach a position from 32N134W to 29N140W on Sun evening. Strong southerly flow, and 6 to 9 ft seas, will precede the front across the discussion waters north of 29N on Sun night. Although the front will stall and wash out from 32N131W 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 32N128W to 16N140W on Tue night. These seas will 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 next week, and intensify as it tracks northwest late in week. $$ Nelson