000 AXPZ20 KNHC 142159 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2145 UTC Tue Nov 14 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 FEATURES... A gale warning remains in effect for the Gulf of Tehuantepec. An earlier scatterometer pass showed 35-40 kt winds within about 60 nm of the coast in the Gulf of Tehuantepec. High pressure north of the area along with lower pressure reaching from the southwest Caribbean to the south of Tehuantepec will continue to support the strong to gale force gap winds through tonight into early Wednesday morning. The ridge will weaken slightly, allowing winds to diminish below gale force, but strong gap winds will persist into Sat. Winds are forecast to increase again to gale force by Sat night as a strong cold front moves into the western Gulf of Mexico. Marine guidance suggests winds of 30-40 kt and building seas of 14-15 ft by early Sun morning. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N84W to 07N125W to 13N140W. Scattered moderate convection is observed within 60 nm either side of the monsoon trough axis between east of 95W, and between 110W and 115W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section for information regarding the ongoing Gulf of Tehuantepec gale warning. Weak ridging west of the area is supporting moderate to fresh winds and 5 to 7 ft seas off Baja California, with the help of residual northwesterly swell. The ridge will weaken and shift closer to the coastline through Wed, allowing winds to diminish through mid week through Fri. The winds increase again to 15 to 20 kt off Baja California Norte by late Fri as stronger ridging builds north of the area, then shifts eastward through Sun allowing the winds to diminish again. Weak northwest winds will persist across the Gulf of California through Fri under the weak pressure pattern. Strong northwest winds are possible by early Sat over the northern Gulf however as high pressure builds over the Great Basin north of the area. The strong winds will reach into the central Gulf of California by Sun before diminishing late Sun as the ridge weakens. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Earlier ship observations continued to show fresh southwest winds to the south of western Panama this morning. These winds are expected to increase through this afternoon to 20 to 25 kt with seas building to 9 ft mainly off the Azuero peninsula through late Thu. The winds and seas are the result of a tight pressure gradient related to 1007 mb low pressure centered over the southwest Caribbean. The fresh to strong winds and seas to 9 ft will persist off western Panama through Thu, when the low pressure weakens and starts drifting farther north. Elsewhere, gentle to moderate winds and seas of 4 to 6 ft are expected N of the monsoon trough, which will fluctuate between 08N and 10N, with moderate to locally fresh S to SW winds and seas of 5 to 7 ft S of the monsoon trough through Thu. REMAINDER OF THE AREA... A 1012 mb low pressure area is centered near 20N132W moving NW at 10 kt. An area of fresh to strong winds and seas to 10 ft is noted within about 150 nm N semicircle of low center. A swirl of low clouds is associated with this low. A passing short wave trough and dry air aloft will cause the low to weaken into a trough during the next 24 hours. Winds and seas north of low will continue to diminish today, and early on Wed winds will be less than 20 kt with seas less than 8 ft. An earlier altimeter pass indicated seas to 10 ft over the waters north of 28N and west of 135W. This is due in part to long period NW swell entering the region. A ship observation showed strong southerly winds near 29.5N135W at 17 UTC. These winds are ahead of 1013 mb low pressure which will move NE with an associated cold front entering the discussion area on Wed. Fresh winds and seas of 8 to 9 ft will follow the front forecast to reach from 30N134W to 26N140W by Wed night. The front will stall and start to dissipate from southern California to 25N140W by late Wed. Residual northerly swell to 8 ft will persist north of 26N and west of 135W through late Fri. $$ Christensen