000 AXPZ20 KNHC 080842 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 655 UTC Mon Jan 8 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 0930 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec Gale Warning: High pressure building behind a cold front moving through the western Gulf of Mexico late Mon will allow gap winds to increase to gale force into the Gulf of Tehuantepec Mon night and last until Tue night. Seas are expected to peak at 14 ft early Tue. Modest winds and seas will persist through mid week. Looking ahead, another gale event is expected Fri. Please refer to the latest high seas forecast issued under AWIPS/WMO headers HSFEP2/FZPN03 for additional details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 08N83W to 05N97W. The intertropical convergence zone continues from 05N97W to 10N126W. More ITCZ extends from 13N132W to beyond 09N140W. Scattered moderate convection is from 03N to 08N between 80W and 90W. Scattered moderate convection is also from 09N to 11N between 125W and 129W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see Special Features section above for more details about the upcoming gale force wind event in the Gulf of Tehuantepec. A weak pressure pattern continues farther north through Mon. A cold front will sweep across the region from off Baja California Norte through the northern Gulf of California Tue, before slowing and eventually dissipating over the waters off the southern Gulf of California and southwest of Los Cabos through late week. Fresh NW winds and NW swell in excess of 8 ft will accompany front. The swell will propagate into the offshore waters off Baja California Norte early Tue, with seas building to around 16 ft by Tue night. Strong SW winds will be over the far northern portion of the Gulf of California later on Tue due to the front, with the possibility of strong western gap winds Tue night in the northern Gulf of California south of San Felipe. Looking ahead, the NW swell will gradually decay off Baja California through Wed, but long period swell to 8 ft will reach the Revillagigedo Islands by early Thu before subsiding. Fresh to possibly strong NW winds will follow the front across the central and southern Gulf of California Wed into Thu with seas to 6 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... High pressure north of the Caribbean Sea is weakening and shifting east. Only fresh overnight pulses expected into the Gulf of Papagayo through mid week. Elsewhere moderate SW flow will persist into Costa Rica and Panama, with light northerly flow off the remainder of the coast of Central America. Seas will remain generally 3 to 5 ft. Expect occasional scattered showers and thunderstorms south of Panama mainly at night. REMAINDER OF THE AREA... A sharp upper trough parked along roughly 130W remains the main weather maker, supporting a surface low and trough mainly north of 15N between 125W and 130W. The latest of these is a 1010 mb low pressure area centered near 30N132W, about to move north of the area. An earlier scatterometer satellite pass indicated fresh to strong winds on the northwest quadrant of the low. Concurrent altimeter satellite passes showed seas of 9 to 11 ft, with a likely component of NW swell mixed in. The short term forecast through tonight has these winds across the region diminishing as the upper trough finally starts to dampen out and lift to the northeast. This will be ahead of another mid to upper level disturbance passing eastward to the north of the region through late Mon. An associated cold front will sweep across the waters north of 20N through Tue. This will be accompanied by strong NW winds and seas in excess of 12 ft mainly over the waters north of 28N. Long period NW swell in excess of 8 ft will also propagate across the region north of 20N through mid week, eventually cover the area north of 10N by late week. $$ Formosa