000 AXPZ20 KNHC 180317 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Sat Feb 18 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 powerful Pacific storm system moving eastward toward the State of California has pushed a cold front across the northern forecast waters. At 0000 UTC, the front extends from 30N120W to 20N130W to 19N140W. Scatterometer data indicate gale force winds on both sides of the front. Very large seas follows the front with seas greater than 12 ft affecting most of the waters N of 23N W of 120W. These hazardous marine conditions are expected to shift eastward across the north waters tonight. The southerly gale conditions and leading edge of large NW swell are already reaching the offshore waters of PMZ009 and PMZ011 and these conditions will persist through late tonight. The northwesterly gale conditions will just briefly reach the far offshore waters of these two zones early on Saturday morning before diminishing to strong to near gale force Saturday evening. Seas behind the front are currently peaking around 25-26 ft across the NW and N central waters then subside very slowly to near 20 ft across the NE waters Saturday afternoon and Saturday night. This large and dangerous swell event will reach the coast of Baja California Norte tonight, and spread southward across the entire western coast of Baja California on Saturday, then reach the Revillagigedo Islands on Sunday, and the Cabo Corrientes region of Mexico Sunday night. See statements from your local meteorological agency on this significant marine event for information on high seas, and associated dangerous beach and surf conditions. Gulf of California Gale Warning: Southerly winds of 20-30 kt across the waters N of 30N will further increase to minimal gale force tonight, ahead of the approaching cold front mentioned above. The front will move east-southeast across the gulf waters tonight 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 tonight. 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 that is expected to produce significant impacts across the Baja California, the Gulf of Baja California or Sea of Cortez and NW Mexico. The GFS computer model suggests that this strong cold front will move SE across the entire Gulf of California tonight through Sat night, probably reaching a position midway between Los Cabos and The Maria Islands. It is unusual to see a cold front from the Pacific moving so far south. Refer to High Seas forecast under AWIPS/WMO headers MIAHSFEP2/ FZPN03 KNHC for additional details on these gale force wind conditions. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The ITCZ and associated convection is located S of the area. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See Special Features section above for more information on the gale warning in the Gulf of California. A strong cold front is approaching the offshore waters W of Baja California Peninsula. The most recent scatterometer pass showed fresh to strong southerly winds across forecast zone PMZ009 and across parts of zones PMZ011 and PMZ013. Gale conditions are expected tonight across these forecast zones with seas building up to 18-20 ft late tonight into Saturday. Refer to Special Features section above for more information. The next Gulf of Tehuantepec gap wind event is expected on Tuesday, reaching minimal gale force winds Tuesday night into early Wednesday morning. This event will be associated with a building ridge across the eastern slopes of the Sierra Madre Mountains and the western Gulf of Mexico. This forecast package shows gale conditions possible across forecast zone PMZ027. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: mainly gentle to moderate winds are expected through most of the forecast period. Gulf of Panama: Moderate to fresh northerly flow is generally expected through Saturday. Cross equatorial long period SW swell continues to affect the waters between Ecuador and the Galapagos Islands (except in the lee of the islands), with seas in the 5-6 ft range affecting the pacific coast of Central America. REMAINDER OF THE AREA... A strong cold front is moving across the north waters producing a large area of gale force winds and very large seas. See the Special Features section for more details. High pressure of 1016 mb centered just south of Los Cabos near 21N109W will dissipate in about 12-24 hours as the above mentioned cold front moves eastward across the north waters, reaching Baja California later tonight. Northwesterly swells with seas greater than 8 ft are currently covering much of the waters W of 120W. This swell event will propagate southeastward covering much the area N of 05N W of 110W on Saturday. Another strong cold front is forecast to approach the far NW corner on Sunday. Fresh to strong SW winds are expected ahead of the front, forecast to enter the discussion area by Sunday evening. Strong to near gale force winds and additional pulses of long period NW swell will follow the front, raising seas to 20-21 ft near 30N140W by Sunday night. $$ GR