000 AXPZ20 KNHC 260253 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Fri May 26 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. ...TROPICAL WAVES... The southern portion of a western Caribbean Sea tropical wave has moved into the far eastern part of the area with axis extending along 82W north of 04N, moving west at 15 to 20 kt. Clusters of scattered moderate to strong convection are observed within 180 nm west of the wave. The wave is under upper level diffluent flow, which is helping to keep the convection active through at least Friday night as the wave continues westward across Central America and the far eastern waters. The southern portion of a tropical wave extends into the area ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The Monsoon Trough axis extends from 10N85W to 11N95W to a 1009 mb low near 13N101W to 10.5N106W to a 1010 mb low near 10N111W to 08N120W to 09N130W. The intertropical convergence zone axis extends from 09N130W to 08N140W. Scattered moderate to isolated strong convection is within 180 nm south of axis between 89W and 92W, and within 60 nm north of the axis between 135W and 138W. Scattered moderate convection is within 120 nm north of the axis between 115W and 119W. In addition, scattered moderate convection is within 120 nm of the low in the southwest quadrant of the low. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A weak high pressure ridge protrudes east-southeastward across these waters from well to the northwest of the area. The associated gradient is supporting generally moderate northwest winds across the Baja California Peninsula waters. Light to gentle northwest to north winds are noted elsewhere over the Mexican offshore waters to Acapulco. Seas are in the 4 to 5 ft range in mixed southwest and northwest swell across these waters, except across the Michoacan through Chiapas offshore waters where winds and seas are higher. This is due to 1009 mb low pressure located near 13N101W. Moderate to fresh south to southwest winds, with seas of 6 to 8 ft in southwest swell are present within 60 nm of the low in the southeast quadrant. Seas in the range 4 to 6 ft are elsewhere across these offshore waters. The low is forecast to gradually dissipate through the next 18 hours or so, allowing for associated winds and seas to subside. The pressure gradient is forecast to tighten slightly to the north of 20N through Friday as the ridge slightly builds into the region, with winds and seas increasing slightly across those areas. Gentle to moderate southeast winds occurring elsewhere between Tehuantepec and offshore of Acapulco will gradually weaken and veer southwest to west through Friday. In the Gulf of California, mainly light to gentle variable winds are expected through the day except in the northern Gulf, with seas of 2 ft or less, except 3 to 5 ft near the entrance to the Gulf. Low pressure just to the north of the area over SW Arizona will linger through the end of the week. A trough extending south to southwest from the low to Baja California Norte will linger as well. Fresh to near gale force southwest to west winds have developed to the southeast side of the trough, and will persist through early Friday afternoon. The winds are enhanced through the gaps in the higher terrain of Baja. Seas are forecast to build to 6 to 8 ft late tonight to the southeast of the trough. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle southwest to west winds prevail between the Papagayo region and Tehuantepec, with seas of 4 to 6 ft in SW swell. Expect westerly monsoonal winds to spread across the coastal waters through Friday as a tropical wave moves across the area through Friday night. Nocturnal offshore winds will pulse to fresh levels near the Gulf of Papagayo by Saturday night, behind the wave, and again on Sunday night. Moderate southwest winds will continue to the south of 09N through Thursday night. A pulse of southwest swell is forecast to propagate through the waters within 250 nm of Colombia and Ecuador through Saturday building seas to 7 ft. Otherwise, little change is forecast through the upcoming weekend. REMAINDER OF THE AREA... A weak ridge extends from 28N140W southeastward through 22N130W to 23N122W. The ridge is slowly shifting southeastward as a weak trough from 32N122W to 26N131W, and a cold front just over the far northwest corner of the area are pushing southward. Moderate northerly winds follow the trough and front in the northern waters, with long period north swell producing seas up to 8 ft across the area from 29N to 32N between 126W and 132W expected late tonight through early Friday afternoon. These seas subside to less than 8 ft Friday evening. Elsewhere north of the deep tropics, the weak ridge will maintain moderate trade winds south of 18N, with seas of 5 to 7 ft expected through Friday. Slightly stronger high pressure to the northwest of the area will build southward by the end of the weekend and into early next week, supporting increasing trades to moderate to fresh levels and resultant seas of 5 to 8 ft across the waters north of the ITCZ. $$ Aguirre