000 AXPZ20 KNHC 110915 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Thu Jan 11 2018 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 0900 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec Gale Warning: A strong cold front will blast southward through the western Gulf of Mexico tonight into Fri, setting the stage for a sustained robust gap wind event expected to begin abruptly around dawn Fri. Winds will quickly increase to gale force. Once winds increase to gale force, they are not expected to fall below gale force until at least Wed night. This event is forecasted to peak at storm force on Sun. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 08N78W to 09N84W to 06N90W to 05N97W. The ITCZ continues from 05N97W to 09N140W. Scattered moderate isolated strong convection is within 75 nm of a weak low centered near 07N134W. An area of scattered moderate showers is noted from 15N to 18N between 130W and 134W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See special features section for information about a gale warning, later expected to be upgraded to a storm warning, in the Gulf of Tehuantepec. A dissipating cold front SE of Baja California Sur extends from 23N107W to 17N116W with no convection. Moderate NW winds and large seas of 10-12 ft are located north of 27N west of Baja California. Winds in the vicinity of the front will diminish today, and seas will gradually subside through Fri. Strong high pressure building over the U.S. Great Basin will generate strong NW winds over the southern two thirds of the Gulf of California Thu evening through Fri, with seas peaking close to 8 ft around dawn on Fri morning near 26N. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A weak pressure gradient over central America is maintaining moderate to fresh gap winds over the Gulf of Papagayo. Strong winds are expected to redevelop there Sat morning as high pres builds over the western Caribbean. Winds could reach gale force on Mon morning. The area of seas developing S of the Gulf of Papagayo will merge with the larger area of seas that will be present south of Tehuantepec on Sun. Elsewhere, light to moderate SW winds will persist S of Costa Rica and Panama. Seas will remain generally between 3 and 5 ft. N winds over the Gulf of Panama could become fresh by Mon morning. REMAINDER OF THE AREA... The pressure gradient between high pres centered near 31N132W and lower pressure in the vicinity of the ITCZ will support fresh trade winds from 15N to 18N between 122W and 137W today. The areal coverage of seas 8 ft or greater will peak today, encompassing waters W of 110W and N of 10N. This large area of high seas will slowly decay Fri and Sat. A cold front reaching the NW part of the discussion area Sun will generate large long period NW swell, and building seas to as high as 21 ft in far northwest waters near 30N140W by Sun evening. $$ Mundell