000 AXPZ20 KNHC 032205 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Jan 3 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A very tight pressure gradient continues along the eastern slope of the Sierra Madre Oriental as a 1036 mb high is analyzed over the Texas/Mexican border at 18 UTC. This tight gradient is inducing northerly gale through the Isthmus of Tehuantepec and out across the Gulf of Tehuantepec. Seas associated with these winds are in the range of 12-15 ft. The gale force winds are forecast to peak near 45 kt late tonight, with seas reaching up to near 19 ft. Model guidance suggests that these winds will slowly diminish to 40 kt after late tonight, and to minimal gale force by early Friday, then to strong N-NE winds on Friday afternoon, with seas in the range of 9-12 ft. The guidance indicated that respite of strong N-NE winds on Friday afternoon will be short-lived as the tight pressure gradient will tighten up again over southeastern Mexico beginning late on Friday afternoon allowing for these northerly winds to increase back up to gale force through the upcoming weekend. Swell generated from the persistent gale force winds will propagate downstream of the Gulf of Tehuantepec, with seas 8 ft or greater reaching as far S as 05N and west to 110W by Friday afternoon. 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 08N82W to 05N99W to 06N111W, where latest scatterometer data depicts that the ITCZ axis then begins and continues to 08N127W to beyond the area at 10N140W. Scattered moderate within 30 nm N of axis between 83W and 84W, and also within 30 nm S of axis W of 138W. ...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. Relatively tranquil marine conditions will persist through Friday allowing for light to gentle winds prevailing across the forecast waters. Seas in the range of 3-5 ft will continue over most of the offshore waters, while seas in the 1-3 ft range will prevail in the Gulf of California. NW swell will induce seas in the range of 5-7 ft through the waters offshore Baja California Norte beginning Thursday night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... NE winds will pulse to fresh to strong in the Gulf of Papagayo through Thursday afternoon, then increase further to near gale force Thursday night into Friday morning as high pressure N of the area intensifies the pressure gradient. Light to gentle NE-E winds will continue elsewhere to the N of 09N, with gentle to moderate S to SW winds expected S of 09N. REMAINDER OF THE AREA... NW swell is propagating across the NW waters. Seas of 8 ft or greater are covering the waters west of a line from 30N124W to 21N127W to 14N140W, with seas peaking near 11 ft over the far NW waters. The swell will continue to propagate southeastward, with seas 8 ft or greater covering much of the water north of 10N and west of 125W by the end of the week. Low pressure is expected to develop over the western portion near 19N132W by early on Friday, with a trailing trough to 15N134W to near 12N137W. The gradient will quickly tighten around the low bringing an increase in winds and seas over the waters mainly N of 20N and to the W 125W. Stay tuned for updated information regarding winds and seas associated with this forecast system in future discussions. The next cold front is expected to move into into the NW corner of the area late on Monday of next week followed by possible gale force northerly winds and building seas. $$ Formosa