000 AXPZ20 KNHC 251607 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... ...GALE WARNING... A surface trough will develop early Thu morning N of the ITCZ W of 132W and then evolve to a low pressure in the late afternoon hours supporting fresh to strong winds from 12N to 17N W of 129W. The low pressure is forecast to intensify along with the pressure gradient between the low and high pressure N of the area. This will lead to the development of near gale to gale force winds starting Thu night through Friday. See the latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFEP2/FZPN03 KNHC for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The ITCZ extends from 03N90W to 08N110W to 04N130W to 05N140W. No significant convection. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Long period NW swell continue propagating SE across the open waters W of 107W. Latest satellite-derived sea height data indicate seas in this area range between 8 and 13 ft, with the highest seas between the Baja California Norte and 127W. These large seas are forecast to subside to 8 to 9 ft by Thursday morning. Hazardous near shore marine conditions and the associated dangerous surf are both expected to continue until the seas subside. Mixing SW and NW swell resulting in seas of 7 to 8 ft are expected between 96W and 110W today, subsiding to 4 to 7 ft on Thu. Gulf of California: moderate N winds this morning are expected to increase to fresh to strong tonight. Strong high pressure is beginning to build across the western United States. The pressure gradient between the high and the Gulf of California will continue tightening throughout Thu with strong N flow expected across the entire Gulf on Thu night, with embedded swaths of near gale force winds by Friday morning. Latest model guidance continues to suggest minimal gale conditions over the northern and central gulf waters on Sat evening. Have gone with gales for zone PMZ017 for now, but extent of the gales may need to be extended to include zone PMZ019 as well during this time frame if the aggressive trend for winds in the models continues. Seas are forecast to build to 11 ft in the open fetch waters along 26N on Fri night and Sat. The pressure gradient will relax on Sun and Mon, allowing winds and seas to subside. Gulf of Tehuantepec: fresh to strong northerly winds are expected to begin on Thu night and rapidly increase to near gale force early Friday morning, with seas building to 10 ft downstream of the gulf near 15N95W. Guidance is beginning to suggest minimal gale conditions beginning late Sun night. 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. Fresh to strong ENE winds may visit this area Sat night and Sun night. 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 is forecast on Thu night. Light to gentle winds, and combined seas of 3 to 4 ft, are generally occurring elsewhere. REMAINDER OF THE AREA... A ridge extends SE from 1029 mb high pressure centered near 32N138W to the vicinity of the Revillagigedo Islands at 18N111W. Large NW swell and combined seas to 14 ft are spreading SE across the discussion waters W of 92W. See special features section for details about a developing low and associated gale conditions. $$ Ramos