000 AXPZ20 KNHC 091605 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1456 UTC Tue Jan 9 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 1200 UTC surface analysis and satellite imagery through 1430 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec Gale Warning: High pressure building southward along the Sierra Madre Oriental behind a cold front over the Isthmus of Tehuantepec is maintaining gale force winds over the Gulf of Tehuantepec. However, the ridge is beginning to weaken. This will allow gale force winds to subside by 00Z this evening. Seas of up to 14 ft this morning will subside to below 8 ft by dawn on Wed. Modest winds and seas will then follow through Thu night. Looking ahead, a much more robust Gulf of Tehuantepec gale event is expected to commence Fri morning. This event may reach storm force on Sat and will continue to beyond Tue. This next event could generate a large downstream area of seas greater than 8 ft. 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 10N84W to 05N90W. The intertropical convergence zone continues from 05N90W to 05N94W to 06N103W to 09N124W. The ITCZ resumes from 09N134W to beyond 09N140W. Scattered moderate and isolated strong convection is present from 04N to 08N between 83W and 89W. A surface trough extending from 07N127W to 14N127W divides the ITCZ. Scattered moderate and isolated strong convection cover as an area from 10N to 18N between 125W to 128W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Feature section above for more details concerning gale force wind event currently in progress over the Gulf of Tehuantepec and the potentially stronger event expected to commence on Fri morning. Weak 1020 mb high pressure currently centered near 21N116W will maintain light winds over the forecast waters in the vicinity of Baja California Sur and Cabo Corrientes today and tonight. A cold front extending from 30N120W to 25N123W to 22N130W will sweep E to NW Baja California Norte today, and to the northern Gulf of California tonight. Fresh to locally strong NW winds and NW swell in excess of 8 ft will accompany the front. The swell will arrive in the offshore waters of Baja California Norte this morning, with seas building to around 13 ft in the far NW waters by dawn on Wed. Strong SW winds are preceding the front and are developing over the far northern portion of the Gulf of California. These strong winds will continue until around midday Wed. Strong gap winds could be in the offing as well tonight 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 Thu evening before subsiding. Strong high pressure building over the great Basin of the United States could generate strong NW winds over the southern two thirds of the Gulf of California Thu night and Fri. Seas could peak around 8 ft on Fri morning near 26N110.5W. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... High pressure north of the Caribbean Sea has weakened and shifted east. Only 15-20 kt winds are pulsing through the Gulf of Papagayo. Strong gap winds could redevelop over the Gulf of Papagayo on Sat morning as high pres builds over the western Caribbean in the wake of another strong cold front. Elsewhere 10-15 kt SW flow will persist S of Costa Rica and Panama. Seas will remain generally between 3 and 5 ft. Expect scattered nocturnal showers and thunderstorms south of Panama through Wed night. REMAINDER OF THE AREA... A sharp upper-level trough is supporting the surface front W of Baja California. The cold front will affect the waters N of 28N with strong NW winds until around midday today. Corresponding seas in this area will run between 12 and 14 ft during this time frame. Long period NW swell generated by NW winds behind the cold front will cause seas to build in excess of 8 ft north of 20N and west of 115W by Thu morning. This area of seas will slowly decay on Fri and Sat. A cold front approaching 30N140W on Sun will generate large long period NW swell. These swell could cause seas in the vicinity of 30N140W to build to 20 ft by Sun evening. $$ CAM