000 AXPZ20 KNHC 210315 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 026 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 0000 UTC surface analysis and satellite imagery through 0245 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A cold front over the eastern Gulf of Mexico has already introduced a strong ridge of high pressure along the Sierra Madre Oriental. A tight pressure gradient over the area between the ridge and lower pressure associated with surface troughing over the eastern Pacific is ushering in the current gale force gap wind event. Winds will abruptly increase to gale force this evening, then to strong gale force by Fri morning. The plume of strong gap winds will reach about 500 nm to the SW of the Gulf of Tehuantepec by late Fri, with seas building as high as 19 ft within the area of strong winds. The gales will persist through Fri night, then diminish on Sat as the high pressure N of the area shifts east. Fresh to strong gap winds will then persist across the Gulf of Tehuantepec through Sun. Another possible gale is forecast for the Gulf of Tehuantepec Sun night through Mon night. Gulf of Papagayo Gale Warning: High pressure will continue to build SE in the wake of the cold front moving from the Gulf of Mexico into the NW Caribbean. This will tighten the pressure gradient over central America and support strong gap winds across the Gulf of Papagayo by late Fri. Winds are expected to further increase and reach gale force Fri night. Winds will diminish below gale force 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, but the areal coverage of the winds will gradually decrease. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 09N74W to 04N80W to 04N99W. The ITCZ continues from 04N99W to 06N108W to 08N122W to 08N132W to beyond 07N140W. Scattered moderate and isolated strong convection is noted from 05N to 07N between 82W and 89W and from 10N to 13N between 117W and 121W. Scattered moderate convection is found from 05N to 11N between 130w and 138W. ...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 offshore waters of the discussion area. Seas in the 10 to 12 ft range will linger off the coast of Baja California Norte this evening but have begun to subside. Seas everywhere outside the Gulf of Tehunatepec will continue to subside and fall below 8 ft through early Sat. The next round of large swell will reach the Baja offshore waters by late Mon. Elsewhere, high pressure over the Great Basin has weakened enough to allow the strong NW winds over the central Gulf of California to become fresh. These winds will diminish to light and variable by Fri evening as the area of high pressure weakens further. 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 30N134W to 26N140W, where it becomes stationary. The front introduced a fresh set of NW swell into the forecast waters yesterday, but seas in the vicinity of the front have already subsided to between 10 and 11 ft as the swell have begun to decay. The front will gradually become diffuse tonight and Fri. High pressure building behind the front will support an area of fresh to strong winds over the trade wind belt N of the ITCZ, W of 135W tonight through Tue night. NW swell continues to prevail across the discussion area. Seas of 8 ft or greater are noted W of 93W. The swell are decaying and seas will subside N of 20N and W of 120W tonight through Sat. An area of confused seas will develop south of 15N between 100W and 110W by late Sat as lingering NW swell mixes with shorter period swell from the Tehuantepec and Papagayo gap events. $$ CAM