000 AXPZ20 KNHC 102205 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Mon Apr 10 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning...strong high pressure building southwestward over the Gulf will increase the pressure gradient over the Isthmus of Tehuantepec early on Wednesday through Thursday afternoon. Strong northerly winds are forecast to begin on Tue night then quickly increase to minimal gale force briefly on Wed morning, then develop again on Wed night into Thu morning. Expect seas to build to 12 to 14 ft downstream of the gulf waters near 14.5N95.5W on Wed and Thu mornings. The pressure ridge gradient will relax on Thu with associated winds diminishing to 20 kt of less by Thu evening. East Pacific Gale Warning...Low pressure north of the area will drag a cold front through the discussion area from 30N to 32N tonight with southerly flow ahead of the front reaching minimal gale force briefly tonight with seas to 12 ft along 32N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 06N87W to 02N102W with scattered moderate isolated strong convection observed within 150 nm either side of a line from 05N86W to 04N100W. Scatterometer winds indicate that the ITCZ forms at 03N108W and extends nw through an embedded trough at 05N121W, then continues sw to 02N130W where it loses identity. Scattered moderate isolated strong convection is observed within 180 nm either side of a line from 05N111W to 09N123W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface ridge extends across the offshore waters to the w of 104W. Moderate to locally fresh anticyclonic winds are observed along the Pacific coast of Baja, with long period nw swell contributing to combined seas of 6 to 8 ft. The pressure gradient will continue to relax with moderate nw flow, and 4 to 7 ft seas expected w of the Baja peninsula early Tue. The pressure gradient will tighten again late Tue, with fresh nw flow forecast to spread se across the waters w of Baja on Tue night into early Wed. Fresh to locally strong nw flow will develop w of Baja late Wed, and persist through early Fri. Gulf of California: Gentle to locally moderate nw flow forecast tonight then light to gentle variable flow expected the remainder of the week. Gulf of Tehuantepec: See special features section above. 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 this week with the most significant gap event expected on Wed night with seas building to 9 ft downstream of the gulf waters near 10.5N87.5W. Gulf of Panama: Moderate to fresh nocturnal northerly flow expected during the overnight hours this week with seas building to 7 to 8 ft downstream of the gulf waters near 06.5N80W. Light to gentle winds, and combined seas of 3 to 6 ft, are occurring elsewhere outside of the swells originating near the gap events. REMAINDER OF THE AREA... See special features section above. Long-period northwesterly swell resulting in combined seas of 6 to 9 ft currently across the area n of 20N between 112W and 125W, are expected to subside by early Tue. A surface high near 32N127W is shifting southward and will allow a cold front to move into the nw waters early tonight, and reach a position from 32N133W to 28N140W late tonight. The front will be accompanied by a strong sw-w-nw wind shift through Tue morning, but mainly across the discussion waters from 29.5N to 32N. Large nw swell, in the form of 7 to 10 ft seas precedes the front by about 480 nm across the waters n of 28N. The high will block the front from about 32N124W to 25N140W on Wed with seas of 8 to 10 ft shifting to n of 31N. Another batch of large nw swell will arrive at 30N140W late Wed behind a re-enforcing cold front with seas building to 8 to 12 ft across the waters from 27N to 32N w of the front on Wed night into Thu. $$ Nelson