000 AXPZ20 KNHC 212204 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Tue Feb 21 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 2100 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec Gale Warning...High pressure is building southward across eastern Mexico in the wake of a frontal system moving slowly eastward across the Gulf of Mexico today. Strong winds generated west of the front are beginning to funnel through the Chivela pass into the Gulf of Tehuantepec, and are believed to have increased to 20-30 kt late this afternoon. These northerly gap winds are expected to increase further to gale force through this evening, with seas building to 12 ft tonight. This gap wind event will be brief as winds peak at minimal gale force this evening and tonight, then diminish below gale force by sunrise Wednesday morning and then gradually diminish to 20-25 kt Wednesday afternoon. Refer to the High Seas Forecast product under AWIPS/WMO headers MIAHSFEP2/FZPN03 KNHC for additional details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... There is no ITCZ over the forecast waters north of the equator. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see above for information on the Gulf of Tehuantepec gale force gap wind event. Moderate to fresh northerly winds prevail across much of the forecast waters west of Baja as indicated by the latest satellite-derived wind data. Seas continue in the 6-9 ft range in NW swell across the Baja offshore waters, and 5-8 ft across the waters adjacent to southwest Mexico. A modest pressure gradient between a 1026 mb high pressure centered near 28N123W and lower pressure across the western flanks of the Sierra Madres is producing fresh to locally strong northwesterly winds across most of the Gulf of California, where seas are running 3- 6 ft. These winds will diminish very slowly over the next 24 hours while the strongest winds shift into N portions of the gulf. A fresh pulse of NW swell generated by a cold front west of the area is moving toward the Baja California Norte offshore waters this afternoon. This swell will continue to propagate across the waters off the west coast of the Baja California peninsula and maintain seas in the 8-12 ft range over this area through early Friday. Building high pressure west of Baja California is expected to produce fresh to strong NW winds along the western Baja California coast north of 25N Wednesday night through Thursday night and over the Gulf of California N of 30N on Thursday morning. Winds will subside as the high weakens in response to low pressure approaching from the west. Seas are then expected to subside below 8 ft in this area Friday night through the weekend. Another cold front could bring yet another round of NW swell to Baja waters on Monday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Moderate to locally fresh winds this morning will subside by this evening. Gulf of Panama: Moderate winds will become light on Wednesday. Otherwise, winds will be in the light to gentle range over the forecast area. REMAINDER OF THE AREA... High pressure of 1026 mb is stationary ear 28N123W. A frontal boundary has stalled across the northern waters from 30N125W TO 21N140W. Winds in the vicinity of this front have diminished to 20 kt or less. Large NW swell generated north of the front continues to produce peak seas of 12-15 ft near 29N133W and propagate SE across the forecast waters. The front is beginning to weaken, and is expected to dissipate later today. This NW swell will continue to dominate the forecast waters, with seas greater than 8 ft covering much of the forecast waters north of 10N and west of 110W. A small area of 20 to 25 kt NE winds is expected to affect the waters from 22N to 25N west of 133W along the dissipating frontal boundary Wednesday and Wednesday night. Areal coverage of seas greater than 8 ft will start to decrease the second half of the week. $$ Stripling