000 AXPZ20 KNHC 250328 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Wed Jan 25 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 0315 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The southern end of a cold front extends across northern Costa Rica, and is accompanied by broken low to mid level clouds. A surface trough extends from 06N86W to 04N94W to 05N108W, and is also accompanied by broken low clouds with intermittent showers. The ITCZ extends from 09N105W to 04N130W to 06N140W, but lacks significant convection. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A low level trough is dissipating from 25N108W to 17N110W, with broken to mid level clouds observed within 75 nm of the trough axis. Long period nw swell in the form of 8 to 13 ft seas, is propagating se across the open waters w of 110W. These large seas are forecast to subside to 7 to 9 ft by late Wed. Hazardous near-shore marine conditions in the associated dangerous surf is expected to continue until the seas subside. Mixing sw and nw swell resulting in seas of 7 to 10 ft are expected between 96W and 110W early tonight, and then expected to subside to 4 to 7 ft on Wed. Gulf of California: moderate nw to n winds tonight are expected to increase to a fresh breeze late Wed, and further increase to locally strong nw winds across the central gulf waters on Wed evening. The gradient will tighten some more throughout Thu with strong nw flow expected across the entire gulf waters on Thu night, with embedded swaths of near gale force winds by late Thu night. Latest guidance is beginning to suggest minimal gale conditions across the central gulf waters on Sat evening, and if this stronger trend continues then possible gale conditions will be reflected in the next package. Seas are forecast to build to 11 ft in the open fetch waters along 26N on Fri night into Sat, with the pressure gradient relaxing on Sun. Gulf of Tehuantepec: strong northerly winds are expected to begin on Thu evening and rapidly increase to near gale force late Thu night, with seas building to 10 ft downstream of the gulf near 15N95W. The north winds will diminish to a fresh breeze at mid day on Fri, then briefly increasing to locally strong on Fri and Sat evenings. Guidance is beginning to suggest minimal gale conditions beginning late Sat night and continuing through Sun. If this stronger trend continues then possible gale wording will be added into the next package. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh ene winds expected tonight and Wed night, then increasing a little with brief strong winds forecast on Thu night, with seas building to about 6 ft. Gulf of Panama: Fresh n winds expected tonight and Wed with guidance suggesting very brief strong winds on Wed night. Then fresh nocturnal northerly flow forecast on Thu night. Light to gentle winds, and combined seas of 3 to 4 ft, are occurring elsewhere. REMAINDER OF THE AREA... A ridge extends se from a 1029 mb high pressure near 31N141W to near 20N108W. Large NW swell with combined seas to 15 ft are spreading se across the discussion waters w of 93W. A surface trough is expected to develop across the tropics s of the ridge on Wed, roughly from 12N140W to 16N128W, and extend from 07N140W to 16N135W to 15N126W on Wed night. Strong ne to e winds will develop just n of the trough, and gradually spread northward out to about 480 nm on Wed night. A surface low is expected to develop along the trough near 12N136W on Thu, with the gradient supporting strong to near gale force winds across the waters from 11N to 24N between 124W and 140W, with seas building to about 18 ft on Fri. $$ Nelson