000 AXPZ20 KNHC 192206 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Mon Dec 19 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 1800 UTC surface analysis and satellite imagery through 2100 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 last 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. A pair of ASCAT scatterometer passes at 1538 and 1624 UTC indicated peak N winds of 40 kt in the northernmost Gulf of Tehuantepec with gales extending south to 14N. The winds should further intensify to storm force conditions this evening and early on Tuesday. Seas likely to reach as high as 18 ft by Tuesday morning given the strength and extent of the gales. 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 and Saturday. Another gale force event is likely. Gulf of California...A gale warning is in effect for the northern Gulf of California. An 1800 UTC ASCAT-A scatterometer pass showed NW 35 kt winds north of 30N in the Gulf this afternoon. A TOPEX altimeter pass showed peak wave heights of 9- 10 ft around 1100 UTC. The gale winds are the result of a strong pressure gradient between a 1053 mb high over Colorado and 1018 mb trough over the southern Gulf of California. It is likely that these conditions are the peak for the event, as the gradient should diminish through early Tuesday 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 06N77W to 07N96W. The ITCZ continues from 07N96W to 10N120W, then resumes at 08N125W to beyond 06N140W. No significant deep convection is occurring in association with the monsoon trough or ITCZ. ...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. Moderate to fresh northerly flow persists over the waters off Baja California today, with seas of 6 to 8 ft based on an altimeter pass. Elsewhere offshore of Mexico, and outside of the Gulf of Tehuantepec and Gulf of California, gentle to moderate breezes and 3 to 5 ft seas will persist. 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 to the Gulf of Fonseca during the overnight and early morning hours through Wednesday morning, with the assistance of the nocturnal drainage flow. Seas should build to 10-11 ft west of 90W. Northeast swell will merge with the Gulf of Tehuantepec gap wind event to provide a large area of 8-12 ft seas from 08N to 13N to 107W Tuesday morning, and from 05N to 13N to 110W on Wednesday morning. Northerly moderate to fresh breezes will pulse across the Gulf of Panama through the end of the week. REMAINDER OF THE AREA... A 1034 mb high pressure is centered north of the area near 35N133W supporting a broad area of fresh to strong northeast to east winds over much of the forecast waters north of 07N and west of 125W. Farther east, a surface trough extends from 08N122W to 15N121W. The trough will drifts northwest into the ridge through the next couple of days. The tighter pressure gradient on the north side of this system will enhance the area of northeast winds through mid week. Seas to 11 ft are noted, per altimeter data, 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. $$ GR/CWL