000 AXPZ20 KNHC 070221 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Fri Apr 07 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 0215 UTC. ...SPECIAL FEATURE... GULF OF TEHUANTEPEC GALE WARNING... Post-frontal high pressure over the sw Gulf of Mexico will continue to support gale force winds of 30 to 40 kt through the Chivela Pass, and across the Gulf of Tehuantepec through sunrise on Fri, with maximum seas of 15 ft developing downstream of the Gulf waters near 14.5N95.5W late tonight. 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 to around sunrise on Sat. Expect only fresh n winds by late Sat afternoon with these conditions continuing through sunrise on Sun. The resultant ne swell, in the form of 8 ft seas or greater, will propagate sw mixing with long period cross- equatorial sw swell, reaching as far s as 08N between 98W and 104w on Fri night before beginning to subside. Expect all associated seas to subside to less than 8 ft on Sat night. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A 1009 mb surface low is over nw Colombia near 09N75W with a surface trough extending sw along 06N77W to 04N82W to 05N97W where scatterometer winds indicate that the ITCZ forms and continues wnw to 06N103W to 03N112W, then turns abruptly sw to 02N131W. Scattered moderate isolated strong convection is observed within 60 nm either side of a line from 03N84W to 03N93W, and within 90 nm either side of a line from 07.5N98.5W to 07N107W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See special features above for on the ongoing Gulf of Tehuantepec gale force gap wind event. Broad surfacing ridging extends e across the offshore waters w of the Baja Peninsula, with gentle to moderate n flow is expected through Sat afternoon. A tightening pressure gradient will then increase the nw flow to a fresh to locally strong breeze which will spread se across all waters w of the Baja Peninsula throughout Sat night, with seas building to 6 to 9 ft. The gradient will relax on Sun night, with moderate to locally fresh nw flow expected early next week. Gulf of California: Light and variable winds expected through this weekend except moderate southerly nocturnal winds forecast n of 30N. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh to locally strong nocturnal drainage winds expected through Sat night with the resultant ne swell propagating wsw to as far sw as 08N92W on Sat. Gulf of Panama: Moderate to fresh nocturnal flow expected during the overnight hours through the middle of next 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... Moderate to locally fresh ne trades expected across the tropics from 05N to 15N w of 110W with the ne wind waves resulting in an area of 6 to 8 ft combined seas forming across the tropics from 06N to 11N w of 128W over the upcoming weekend. A series of weak colds fronts will dip into the nw waters accompanied by a strong sw-w-nw wind shift across the discussion waters n of 30N. Large post frontal nw swell in the form of combined seas of 8 to 12 ft to the s of 30N, and 10 to 14 ft between 30N and 32N, will propagate e and cross 120W on Fri night as the seas subside from the w. By Sun night expect 6 to 9 ft seas across the entire waters w of 110W. $$ Nelson