000 AXPZ20 KNHC 170317 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Fri Feb 17 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 0300 UTC. ...SPECIAL FEATURES... Gale Warning: A major Pacific storm moving eastward toward the State of California will push a cold front across the northern forecast waters. This front will bring gale force winds and very large seas. The cold front is forecast to reach a position from 30N127W to 22N140W on Friday at 1200 UTC. At that time, minimal gale force southerly flow will develop within about 90 nm ahead of the front while NW winds in the 30-40 kt range and building seas up to 24-25 ft are expected behind the front, particularly north of 27N west of the front to 138W. These hazardous marine conditions will shift E across the north waters Friday and Friday night. The southerly gale conditions will reach the far offshore waters of PMZ009 and PMZ011 late Friday, then diminish to near gale force on Fri night. The northwesterly gale conditions will just briefly reach the far offshore waters of these two zones early on Saturday morning, then diminish to strong to near gale force flow that will shift E across the waters N of 20N through late Saturday. Seas will begin to build across the offshore waters west of Baja California tonight, with large NW swell, in the form of 8 to 20 ft seas, reaching the entire coast of Baja California Friday night into Saturday. Seas will subside 8 to 16 ft on Sunday, and to 12 ft or less on Monday. See statements from your local meteorological agency on this significant marine event for information on dangerous beach and surf conditions. Gulf of California Gale Warning: Gentle to moderate southerly flow will develop tonight across the Gulf of California with increasing winds to 20-30 kt across the waters N of 30N on Friday. Then winds will further increase to minimal gale force across the north waters by Fri evening ahead of the major cold front described above, that will move across the gulf waters Friday night and Saturday. Minimal gale force southerly winds are possible over the gulf waters S of 28N on Saturday. Strong to gale force winds are also expected over the Baja California Peninsula mainly north of 28N late Friday and Friday night. Strong southerly winds, with frequent gusts to gale force are also expected to affect the States of Sonora and Sinaloa on Saturday. See statements from your local meteorological agency on this significant weather event forecast to produce a high impact across the EPAC waters, California and NW Mexico. Refer to High Seas forecast under AWIPS/WMO headers MIAHSFEP2/ FZPN03 KNHC for additional details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The ITCZ and associated convection is located S of the area. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of California: See Special Features section above for details. Gulf of Tehuantepec: Mainly northerly winds to 10 kt and seas of 5-7 ft in long period SW swell are expected tonight and Friday. Then, mainly light to gentle winds will prevail across this gulf most of the forecast period with seas sudsiding to 3-4 ft during the upcoming weekend. Scatterometer data show gentle to moderate NW winds across the waters W of the Baja Peninsula with seas of 4-6 ft. Another round of NW swell will reach the coast of Baja to the N of 25N tonight, then spread SE across all waters W of Baja Peninsula by late Friday. The focus then turns to an approaching cold front with gale conditions expected to develop on both side of the front, and very large NW swell in excess of 15 ft through the weekend. Refer to Special Features section above. Light winds and 4-6 ft seas in long period SW swell are forecast elsewhere across the offshore waters N of the Gulf of Tehuantepec through Fri. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: moderate to locally fresh NE-E winds are expected tonight and early Friday with mainly gentle to moderate winds thereafter. Gulf of Panama: Moderate to fresh northerly flow is generally expected through Sat. Cross equatorial long period SW swell continues to affect the waters between Ecuador and the Galapagos Islands (except in the lee of the islands), raising seas to 6-7 ft based on an altimeter pass. This swell event is affecting the pacific coast of Central America. Seas will subside to 5-6 ft on Friday. REMAINDER OF THE AREA... A cold front is over the NW part of the forecast area and extends from 30N130W to 25N140W. A second cold front has reached the NW corner of the forecast region and stretches from 30N136W to 28N140W. Fresh to strong winds, with frequent gusts to gale force are expected on either side of the fronts tonight. These front will merge by early Friday morning. Then, gale conditions are forecast behind and ahead of the merging front. Please, see Special Features for details. A 1020 mb high pressure is center near 25N123W. This system will dissipate in about 24 hours as the above mentioned cold front moves eastward across the north waters. A couple of weak trough are also noted. One extends from 14N108W to 07N111W. Isolated moderate convection is on the east side of the trough near 12N106W. The other trough extends from 04N94W to a 1010 mb low pressure located near 03N97W to 01N105W. Scattered moderate convection is from 02N to 04N between 92W and 97W. $$ GR