000 AXPZ20 KNHC 300914 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 614 UTC Sat Dec 30 2017 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 0900 UTC. ..SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: High pressure north of the area has weakened and winds funneling into the Gulf of Tehuantepec have diminished. Overnight scatterometer pass indicates a large area of 30 kt winds over the Gulf of Tehuantepec. Despite this, have decided to keep the gale warning up until early morning as there remains a large area of gale force winds at 30 meters. Overnight hours have the added component of nocturnal drainage flow as well as mixing of the 30 meter winds to the surface. The gale warning will be brought down this morning when the drainage flow and mixing of winds decreases. Winds over the southwest Gulf of Mexico will veer today and Sunday. This will further diminish winds funneling into the Gulf of Tehuantepec. By Sunday, winds will diminish to 20 kt or less, bringing an end to the latest Gulf of Tehuantepec gap wind event. Refer to the latest high seas forecast issued under AWIPS/WMO headers HSFEP2/FZPN03 for more details. Gale Warning: Deepening low pressure will approach the northwest portion of the forecast area Sunday. The pressure gradient between this deepening low and high pressure to the west of the forecast area will bring a period of gale force winds over the far NW waters, mainly north of 28N and west of 138W late Sunday night into Monday morning before winds diminish. The winds will also usher in a large set of NW swell, with seas peaking near 22 ft by Monday morning. Seas will slowly subside while propagating southeastward over the week. By midweek, combined seas of 8 ft or greater will cover much of the waters north of 10N and west of 120W. Refer to the latest high seas forecast issued under AWIPS/WMO headers HSFEP2/FZPN03 for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 07N77W to 07N97W. The ITCZ extends from 07N97W to 08N116W to 09N128W. It resumes from 09N131W to 09N140W. Scattered moderate isolated strong convection was noted north of 06N between 79W and 83W. Scattered moderate isolated strong convection was noted from 06N to 09N between 101W and 105W. Scattered moderate isolated strong convection was noted from 07N to 13N between 110W and 120W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: Please refer to the special features section above for details on the latest Gulf of Tehuantepec gale event. Looking ahead, a strong cold front will push into the Gulf of Mexico late on Sunday. The front will reach the Bay of Campeche Monday, with strong high pressure in its wake expected to induce the next gale force gap wind event over the Gulf of Tehuantepec. This next gale force gap winds event has the potential to be a strong and long lasting event, persisting for much of the next work week. Elsewhere, tranquil marine conditions are expected with light to gentle winds prevailing over the forecast waters. Seas in the range of 3 to 5 ft will continue over the offshore waters, while seas in the 1 to 3 ft range will prevail in the Gulf of California. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... NE winds will pulse to fresh to strong over the Gulf of Papagayo through the middle of next week. Light to gentle NE to E winds will prevail elsewhere N of 09N, with gentle to moderate S to SW winds expected S of 09N. REMAINDER OF THE AREA... Please see above in special features section for more on the gale warning over the NW waters, and associated swell. A cold front has moved into the NW waters, currently extending from 30N139W to 26N140W. Scattered moderate and isolated strong convection is noted within 30 NM east of the front. Latest scatterometer pass suggests winds of 20 to 25 kt north of 28N within 30 nm east of the front. A fresh set of NW swell has moved into the NW waters with this front, with combined seas reaching near 9 ft. Winds and seas associated to this front will fall below advisory criteria today. Latest scatterometer pass indicates a weak surface trough has developed from 18N122W to 11N124W, and depicts fresh to strong winds from 16N to 18N east of the trough to around 121W. Winds and seas associated to this trough are expected to diminish below advisory criteria today. $$ AL