000 AXPZ20 KNHC 061558 CCA TWDEP Tropical Weather Discussion...Corrected NWS National Hurricane Center Miami FL 1530 UTC Sat Jan 6 2018 Corrected to add Monsoon Trough/ITCZ paragraph 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 1500 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A tight pressure gradient over southeastern Mexico continues to support gale force N-NE winds in the Gulf of Tehuantepec. Gale winds are expected to persist until Sunday morning, then continue below gale force through Sun evening. NE swell generated by the persistent strong winds will propagate downstream, with seas 8 ft or greater reaching beyond 10N and westward to beyond 100W tonight. Please refer to the latest high seas forecast issued under AWIPS/WMO headers HSFEP2/FZPN03 for more details. A strong low pressure system is located near 28N131W with a pressure of 1010 mb. A stationary front extends southward to 17N132W. The surface low is related to an upper level cyclone and sharp trough anchored to the northwest, which is also supporting a broad area of showers and a few thunderstorms from 15N to 30N between 125W and 130W, or within 300 nm east of the stationary front. Earlier scatterometer satellite passes have shown periods of winds reaching minimal gale force near the storm center, possible related to short term thunderstorms. The low pressure is expected weaken very slowly through the next 24 to 36 hours as it drifts north of the area, with the probability of winds reaching gale force will gradually decrease accordingly over the next several hours. The supporting upper trough will support development of another surface low near forming by Sunday near 25N125W, which will lift north following the first low through early next week. An earlier altimeter pass showed seas at 15 ft near the center of the low. This will subside, but will be overtaken by longer period NW swell 8 ft or greater through mid week. Please 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 08N78W to 05N95W. The intertropical convergence zone continues from 05N95W to 11N130W, and from 10N135W to 06N140W. From 04N to 08N between 83W and 88W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see Special Features section above for more details about the ongoing gale force wind event in the Gulf of Tehuantepec. Looking ahead, another gale wind event is possible in the Gulf of Tehuantepec early next week as high pressure builds behind the next cold front forecast to move into the Gulf of Mexico. NW swell will propagate into the offshore waters off Baja California Norte Tuesday, with seas building to around 13 ft by Tue night. Elsewhere, relatively tranquil marine conditions are expected during the period. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Winds will pulse to 30 kt in the Gulf of Papagayo tonight, and again Sunday night into early Monday. The Papagayo gap winds will diminish through mid week. Light to gentle NE-E winds will prevail elsewhere to the N of 09N, with gentle to moderate S to SW winds expected S of 09N. REMAINDER OF THE AREA... Please see Special Features section above for details regarding a gale force low center near 130W. A sharp upper trough remains quasi-stationary along 135W, supporting showers and thunderstorms from 15N to 30N between 125W and 130W. The subtropical ridge remains fairly week due the presence of the active low pressure areas, keeping trade wind flow and local wind waves relatively modest. Long period NW swell 8 ft or greater will propagate across most the area through mid week. $$ Christensen