000 AXPZ20 KNHC 200344 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Tue Dec 20 2016 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 0300 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec...A storm warning is in effect for the Gulf of Tehuantepec. A strong Gulf of Tehuantepec gap wind event commenced Sunday night due to a cold front that crossed the Gulf of Mexico. Cooler, drier air behind the front has been moving across the isthmus of Tehuantepec into the Gulf of Tehuantepec. Unfortunately, no recent wind observations have been available in the Gulf. There was, however, a 2150 UTC TOPEX altimeter pass showing peak wave heights of 14-16 ft. Peak winds currently are around 45 kt with peak wave heights of around 18 ft. The winds should further intensify to storm force conditions by early Tuesday. Seas likely to reach as high as 20 ft by Tuesday morning given the strength and extent of the storm and gale winds. Winds should very gradually diminish below gale force with subsiding seas by Thursday as the air mass to the north modifies and shifts east. After a brief hiatus on Thursday, the next cold front moving across the Gulf of Mexico is likely to reinforce the Tehuantepec event on Friday. Another gale force event is thus likely to occur Friday and early Saturday, before diminishing for good by late Saturday. Gulf of California...A gale warning is in effect for the northern Gulf of California. Unfortunately, no recent wind observations have been available in the Gulf. There was, however, a 2140 UTC TOPEX altimeter pass showing peak wave heights of 8-10 ft. Peak winds currently are around 35 kt with peak wave heights of around 10 ft. The gale winds are the result of a strong pressure gradient between a 1042 mb high over Colorado and trough along the southern Gulf of California. It is likely that these conditions are the peak for the event, as the gradient should diminish later today as the high weakens and shifts eastward, leaving areas of 20 to 25 kt winds across the Gulf. Winds should diminish below 25 kt by early Wednesday. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 07N78W to 06N100W. The ITCZ continues from 06N100W to 12N119W to beyond 06N140W. Scattered moderate convection is occurring within 120 nm south of the ITCZ between 118W and 125W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A storm warning has been issued for the Gulf of Tehuantepec and gale warning is in effect for the northern Gulf of California. Please, see Special Features section above for details. Elsewhere offshore of Mexico, winds are 20 kt or less and seas below 8 ft. Later today, a strong cutoff low will induce a trough along 117W between 15N and 20N. Easterly winds up to near gale should develop east of the trough by late Tuesday with seas picking up to about 10 ft. This should quickly diminish on Wednesday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to strong northeast winds are expected to pulse from the Gulf of Papagayo during the overnight and early morning hours through Wednesday morning, with the assistance of the nocturnal drainage flow. Locally, these winds will produce up to 8 ft seas. But the northeast swell will merge with the Gulf of Tehuantepec gap wind event to provide a large area of 8-12 ft seas from 05N to 14N between 90W and 105W Tuesday night, and from 02N to 13N between 90W and 115W on Wednesday night. Elsewhere in the region, winds will remain 20 kt or less and seas below 8 ft through Saturday. REMAINDER OF THE AREA... A 1033 mb high pressure is centered north of the area near 35N136W supporting a broad area of fresh to strong northeast to east winds over much of the forecast waters north of 13N and west of 125W. Seas to 12 ft are noted from a 2330 UTC TOPEX altimeter pass, within the area of these fresh to strong winds. The high pressure is forecast to move SE while slightly weaken. As a result, the aerial coverage of fresh to strong winds will decrease by Wednesday and remain limited through Saturday. $$ CWL