000 AXPZ20 KNHC 061605 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1517 UTC Wed Dec 6 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 1200 UTC surface analysis and satellite imagery through 1545 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 elsehwere 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 soutward to 26N and while the winds veer around to the N-NE. Also of significane is that wavehight 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 maxumim 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 maximun waveheights building to around 11 ft per latest 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 seas of 9-11 ft today. The front west of the area will then weaken Thu and dissipate just NW of the discussion area early Fri as winds diminish over the area. Although winds will diminish, additional NW swell greater than 8 ft will continue to affect these waters through the end of the week. Looking ahead, strong southerly flow will return late Sat north of 25N and of 135W ahead of yet another cold front approaching from the NW, along with a fresh set of large NW swell. Elsewhere, long period swell to 8 ft persisting across much of the area south of 15N will decay below 8 ft through Fri. A new round of NW swell to 9 ft will propagate into the discussion area, encompassing the region north of 15N and west of 130W by Thu night, then most of the area west of 120W by late Fri into Sat, mixing with shorter period NE waves north of 20N and east of 125W. $$ Aguirre