000 AXPZ20 KNHC 061637 CCA TWDEP Tropical Weather Discussion...Corrected NWS National Hurricane Center Miami FL 1605 UTC Wed Dec 6 2017 Corrected header time 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 1600 UTC. ...SPECIAL FEATURES... Gulf of California: An extensive area of strong high pressure from the U.S. Great Basin and northern Rockies will continue to support fresh to occasionally strong NW winds over the northern Gulf through late tonight. The gradient will tighten further into Thursday morning as reinforcing high pressure follows in behind a cold front moving southward along the front range of the Rockies. This will allow for the fresh to occasionally strong winds to develop into gale force 30-35 kt winds over the section of the gulf that covers from 27N to 29.5N by around 12Z on Thursday. NW winds of 20-30 kt are expected elsewhere across the gulf N of 26N. Latest model guidance impressively shows that these gale wind conditions will persist through late Thursday night as they surge southward to 26N and while the winds veer around to the N-NE. Also of significance is that waveheight model guidance indicates that seas will build to maximums of 10 and 11 ft over the northern gulf waters by early Thursday afternoon and to include the central portion of the gulf by late Thursday night. Winds and seas will then diminish into Sunday as the aforementioned high pressure N of the area weakens. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The Monsoon Trough axis extends from 10N85W to 07N90W to 07N100W, where it transitions to the Intertropical Convergence Zone (ITCZ) and continues to 08N105W to 09N120W to 11N128W where it ends. It then resumes at 11N135W southwestward to beyond the area at 09N140W. Scattered moderate to isolated strong convection is within 60 nm of the axis between 110W-116W. Scattered moderate convection is within 60 nm N of the axis between 116W-119W, and also within 30 nm of 08N104W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: N to NE winds of 20-25 kt are funneling into the gulf with maximum waveheights up to 9 ft. These winds will continue through early tonight before increasing to 20-30 kt late tonight as a strong cold front drops southward over the western Gulf of Mexico waters and southeastern Mexico. The tight pressure gradient over southeastern Mexico will keep this wind range through Friday, with maximum waveheights building to around 11 ft per latest TAFB NWPS wave guidance. Looking ahead, strong high pressure will press southward in the wake of the strong Gulf of Mexico cold front will favor the development of a persistent strong gale event for the Gulf of Tehuantepec beginning on Friday night and to possibly continue through the upcoming weekend. Elsewhere off the Pacific coast of Mexico, weak high pressure is maintaining gentle to moderate breezes across the region. High pressure building to the N of the area will result in strong gap winds pushing across low lying area of Baja California Norte and into adjacent waters Thu. A larger plume of strong NE winds will push off the coast of Baja California Sur north of Cabo San Lazaro beginning on Thursday night and through Friday before diminishing Friday night and Saturday. Waveheights associated with these winds are expected to build to a maximum of 10 or 11 ft reaching from near shore to beyond 250 nm offshore. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: NE winds of 20-25 kt through the Gulf of Papagayo will diminish to 15-20 kt this afternoon, then pulse back up to 20-25 kt tonight and diminish back to 15-20 kt Thursday morning. Elsewhere, light to gentle N to NE winds are expected N of the monsoon trough, and mainly gentle to moderate S to SW winds are expected to the S of the monsoon trough. Seas are in the 5 to 7 ft range in SW swell this evening to the S of the monsoon trough, and will subside to 4-6 ft through mid week. Large NW swell of 8-10 ft from the upcoming Tehuantepec gap wind event will spread across the offshore waters of Guatemala late this week and over the weekend. REMAINDER OF THE AREA... The pressure gradient is tightening over NW waters ahead of an approaching cold front. This will lead to fresh to strong SE to S winds NW of a line from 32N132W to 26N140W with waveheights in the range of 9-11 ft today. The front is forecast to weaken as near the far NW corner of the area late tonight, at which time the area of fresh to strong SE to S winds will be confined to N of 29N between 133W-135W with maximum waveheights reaching to 10 ft. By early on Thursday, the cold front is forecast to be weakening from near 32N138W to SW of the area at 28N140W as a second cold front makes headway towards the over waters within 400 nm NW of the discussion domain. This next cold front is forecast be just the NW corner of the area by early on Friday. The area of fresh to strong SE to S winds is forecast to diminish to 15-20 kt by 12Z Friday, however, of significance with respect to marine interests is a very large area of NW swell that expected to encompass a large chunk of the W and central sections of the area to the W of a line from 32N127W to 20N125W to 08N140W by early on Friday with induced waveheights in the range of 8-12 ft. The highest of this range to be located in the far NW portion. A surface trough along 128W/129W from 09N-18N is drifting westward. A tight gradient will develop N and NE of this trough between it and strong high that shifts eastward over the central and NE waters. This will lead to NE-E 20-25 kt from 19.5N-22N between 128W-131W Thursday evening with induced waveheights of 8- 10 ft, and within 60 nm of a line from 21N125W to 20N129W early on Friday as trough will be along 21N125W to 15N132.5W with same type of seas. The trough will weaken on Friday night allowing for the tight gradient to slacken. This will diminish the winds to 15-20 kt. Elsewhere, long period NW swell producing seas of 8 ft to the S of 14N between 98W-117W and also S of 05N between 117W-126W will gradually diminish in coverage through late Thursday night, with seas subsiding to less than 8 ft and winds to 20 kt or less early on Friday. $$ Aguirre