000 AXPZ20 KNHC 210915 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Fri Dec 21 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 FEATURES... Gulf of Tehuantepec Gale Warning: High pressure building southward in the western Gulf of Mexico behind a cold front has induced gale force winds funneling through the Isthmus of Tehuantepec into near-shore waters. A scatterometer pass at 0300 UTC and an oil tanker, the Genmar Compatriot, both reported surface winds to 40 kt. The plume of strong gap winds will reach about 500 nm to the SW of the Gulf of Tehuantepec by this afternoon, with seas building as high as 19 ft within the area of strong winds. The gales will persist through tonight, then diminish on Sat as high pressure N of the area shifts east. Gulf of Papagayo Gale Warning: High pressure will build behind a cold front moving into the NW Caribbean, tightening the pressure gradient over Central America. Winds are expected to increase to gale force tonight, then diminish below gale force by early Sat. Seas could top out around 13 ft between 60 and 150 nm downstream of the Gulf Sat morning. Strong gap winds will continue flowing over the Gulf of Papagayo through Tue night. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 08N78W to 05N93W. The ITCZ continues from 05N93W to 07N121W to 05N140W. Scattered moderate convection is noted from 04N to 07N between 85W and 89W and from 06N to 08N between 104W and 108W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features Section for more on the gale force gap wind event commencing over the Gulf of Tehuantepec. Subsiding long period NW swell will continue to propagate across the region. Seas of 8 ft or greater cover much of the open ocean waters in the discussion area. Seas everywhere outside the Gulf of Tehunatepec will continue to subside through early Sat. The next round of large swell will reach Baja California offshore waters by late Mon. Elsewhere, weakening high pressure over the Great Basin supports fresh NW winds in the central Gulf of California, which will become light and variable by tonight. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please the Special Features Section for more on the upcoming gale force gap wind event over the Gulf of Papagayo. Strong N winds are expected over the Gulf of Panama Fri night through Sun night. Seas will peak around 8 ft Sun morning. Elsewhere, gentle to moderate winds will persist, with seas in the 4 to 7 ft range. REMAINDER OF THE AREA... A cold front extends from 30N133W to 26N135W to 25N140w. Seas in the vicinity of the front are 9-10 ft as NW swell begins to decay. The front will slowly become diffuse today. High pressure building behind the front will induce an area of fresh to strong winds north of the ITCZ and west of 135W through the weekend. NW swell across the discussion area is decaying and seas will subside N of 20N and W of 120W through Sat. An area of mixed swell will develop south of 15N between 100W and 110W by late Sat as lingering NW swell mixes with shorter period NE swell from the Tehuantepec and Papagayo gap wind events. $$ Mundell