000 AXPZ20 KNHC 280320 CCA TWDEP Tropical Weather Discussion...Corrected NWS National Hurricane Center Miami FL 2205 UTC Wed Dec 27 2017 Corrected Special Features Section 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: Building high pressure over the western Gulf of Mexico and eastern Mexico will induce gale force northerly winds through the Chivela Pass into the Gulf of Tehuantepec tonight, and continue through Friday morning. Waveheights are expected to reach a range of 10-14 ft early on Friday with these gale force winds. As the tight pressure gradient over southeastern Mexico weakens during Friday and through Saturday, this will allow for winds and seas. Beyond Thursday, a strong cold front will enter the Gulf of Mexico by Sunday night, and move across the western Gulf of Mexico on Monday. Strong high pressure will ridge southward in the wake of the front along the Sierra Madre Oriental mountains, with the associated tight pressure gradient expected to usher another round of winds to gale force across the Gulf of Tehuantepec. Presently, model guidance indicates that these winds may reach strong gale force category. There may be a possibility that even storm strength winds could occur. 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 axis extends from a 1009 mb low near 05N78W to 07N87W to 06N98W to 06N109W, where latest scatterometer data indicates it transitions to the Intertropical Convergence Zone and continues westward to 10N120W to 10N129W and to beyond 08N140W. No significant convection is noted at the present time. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the special features section above for details on a Gulf of Tehuantepec Gale event. A fairly tranquil synoptic pattern associated with a nearly stationary subtropical high to the W of California and a surface ridge extending SE from the high will persist for several days. This will maintain gentle to moderate NW to N winds off Mexico through the weekend. Seas will be in the general range of 4-6 ft over the offshore waters and 2-4 ft in the Gulf of California. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate high pressure gradient in the western Caribbean will continue to support fresh to strong NE winds from 09N to 11N east of 90W, including the Gulf of Papagayo, through Sun night with seas to 7-9 ft primarily from NE wind waves. Mainly gentle winds are expected elsewhere through the end of the week, with offshore seas generally 4-5 ft. REMAINDER OF THE AREA... Long-period NW swell is producing 8-10 ft seas north of 15N and west of 125W. Seas will continue to gradually diminish today as the peak swell continues moving SE. Divergence aloft on the southeast side of an upper trough along 120W along with jet stream energy along the jet stream branch that stretches from the base of the trough northeastward to just S of Baja California and towards central Mexico is supporting an area of scattered showers and thunderstorms from 10N to 18N between 109W and 119W. A surface trough and weak low pressure area is expected to form along the intertropical convergence zone on Thursday between the area area roughly between 120W and 123W in association to the upper trough. The trough and low pressure is expected to drift westward over the next 48 hours then dissipate. The gradient between these features and the high pressure over the northern waters will tighten enough to increase the trades slightly from 15N and 20N between 118W-130W through Friday, with seas building to 8-9 ft due to a mix of NE wind waves and longer period NW swell. There are expected to be pockets of strong trades from about 18N- 21N between 123W-127W. $$ Aguirre