000 AXPZ20 KNHC 250955 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 801 UTC Mon Dec 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 0600 UTC surface analysis and satellite imagery through 0830 UTC. ..SPECIAL FEATURE... ...Gulf of Tehuantepec Gale-Force Winds... A high pressure ridge extending S over the Sierra Madre Oriental range from Texas is maintaining a gap wind event over the Gulf of Tehuantepec. Gale force winds will persist until Tue morning as a reinforcing shot of cold air enters the Gulf of Mexico. Thereafter, fresh to strong winds are expected to persist over the Gulf through Thursday night. Winds will be strongest at night due to nocturnal drainage flow. Seas in the Gulf of Tehuantepec should peak around 14 ft on Tuesday morning, Strong to near gale force winds will sustain wave heights of 8 ft or greater through Thursday night. Another cold front entering the Gulf of Mexico could usher in the next gap wind event beginning on Fri. Please refer to the latest high seas forecast issued under AWIPS/WMO headers HSFEP2/FZPN03 for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... An east to west surface trough extends from 10N75W to 09N84W to 06N95W. The ITCZ continues from 06N95W to 08N108W to 09N121W to 08N130W to beyond 11N140W. Scattered moderate and isolated strong convection is observed from 05N to 09N between 77W and 81W. Scattered moderate convection is seen from 05N to 08N between 100W and 103W. A surface trough extends from 19N121W to just north of the ITCZ axis near 10N121W. Scattered moderate and isolated strong convection is found from 10N to 15N between 112W and 120W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the special features section above for details on the Gulf of Tehuantepec Gale event. Elsewhere, mainly gentle to moderate winds with benign marine conditions are expected through Thu. NW swell of 6 to 8 ft generated by strong winds off the coast of California could enter the far NW offshore waters of Baja California Norte. Low pressure over interior Mexico could combine with high pressure NW of the area to generate fresh to strong winds between Cabo San Lucas and Cabo Corrientes on Friday afternoon and evening. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Strong gap winds over the Gulf of Papagayo will continue pulsing through Friday night, with the broadest extent of the winds occurring tonight and Tue night. Seas will peak between 8 and 9 ft during this time frame. NE swell to 9 ft will sideswipe the western offshore waters of Guatemala Monday and Tuesday as swell disperse from the Gulf of Tehuantepec gap wind event. Otherwise, gentle to moderate winds and seas of 5 to 7 ft can be expected through Fri. REMAINDER OF THE AREA... A stationary front crosses the NW corner of the discussion area from 30N136.5W and extends to 24.5N140W. The front has begun to weaken. Fresh to strong S winds that were formerly present N of 27N and up to 120 nm east of the front have subsided. The front will complete the transition to a surface trough by this evening. Residual NW swell of 8 to 11 ft generated to the NW of this boundary earlier will slowly propagate SE and disperse through Wednesday as seas W of 120W and N of 10N subside to around 8 ft. A reinforcing round of NW swell will maintain sea heights between 8 and 9 ft N of 20N and W of 130W on Wed and Wed night. Forecast models are also hinting at increasing winds late Tue and Wed as the pressure gradient tightens between a nearly stationary surface trough currently extending from 19N120W to 10N121W and high pressure building to the north. Winds in the vicinity of the trough are currently forecast to reach fresh speeds Tue night through Thu. The combination of the wind waves and NW swell will cause seas to build to between 8 and 9 ft in this area. Elsewhere, moderate to fresh winds will prevail as seas generally run between 6 and 8 ft. $$ CAM