000 AXPZ20 KNHC 010949 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 641 UTC Fri Dec 1 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: High pressure north of the area is supporting a pressure gradient tight enough to result in pulses to gale force through the Gulf of Tehuantepec through Saturday morning, when the high pressure shifts eastward allowing wind to diminish slightly. Seas are reaching 14 ft in the Gulf of California with seas to 8 ft extending as far as 650 nm downstream to the WSW of the Gulf, and is starting to mix with longer period NW swell. Seas will subside to 8 to 10 ft through Sunday as the winds diminish. Winds will diminish to less than 20 kt and seas subside to less than 8 ft by early Monday. Looking ahead, another gale event is expected starting mid week related to a strong cold front moving across the western Gulf of Mexico into southern Mexico. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N85W to 07N93W to 08N105W, where it transitions to the intertropical convergence zone and continues 08N140W. Scattered moderate convection is noted within 120 nm north of the monsoon trough between 95W and 100W, and within 120 nm north of the ITCZ between 110W and 115W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see Special Feature section for detail concerning the gale warning in the Gulf of Tehuantepec. Elsewhere, an upper disturbance will bring a few showers to Baja California Norte and the northern Gulf of California through Sat. Weak ridging across the region will support gentle to moderate northerly winds throughout the area into early next week. Long period northwest swell propagating across the waters offshore of Baja California the past 2 days has reached to near 105W, and is producing seas of 6 to 9 ft across the waters from Baja California sur to south of Manzanillo. Reinforcing NW swell is also moving into the waters off Baja California Norte, producing combined seas 8 to 13 ft. This new pulse of swell will reach as far south as the Revillagigedo Islands at 10 ft swell by early Sat, then decay below 8 ft by late Mon. High pressure building in the wake of a cold front moving across the southwest U.S. Sunday night through Monday night and will force strong NWly winds through the full length of the Gulf of California Monday through Tuesday. Looking ahead, the high pressure will build through mid week, possibly bringing winds to gale force to the northern Gulf of California with seas 8 to 12 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: A modest pressure gradient between high pressure over the western Gulf of Mexico and lower pressure across the southwest Caribbean is producing fresh offshore gap winds across the Papagayo region. These winds will be enhanced with overnight drainage effects for the next few days, peaking near 25 kt during the late night through late morning hours. Seas downstream will build to 6 to 8 ft during the peak winds, with the winds and seas diminishing slightly each late afternoon through evening. Light to gentle N to NE winds, and 4 to 5 ft seas are expected elsewhere through Sat north of the monsoon trough. Moderate southerly winds, and 4 to 6 ft seas, are forecast south of the monsoon trough. Northerly swell generated in the Gulf of Tehuantepec will reach the area beyond 150 nm off Guatemala through the end of the week. REMAINDER OF THE AREA... A large area of NW swell producing seas of 8 to 13 ft will continue to propagate across the region west of 110W. 1029 mb high pressure near 32.5N137W is enhancing fresh winds north of 15N and west of 125W, and fresh to strong trade wind flow between 10N and 15N west of 130W. The ridge will weaken through tonight, allowing these winds to diminish. A mid to upper level disturbance near 20N120W will persist through Sat, supporting the development of a surface trough along 135W between 15N and 20N. The trough will amplify and drift NW through early next week as an upper cyclone stalls near 30N140W. The gradient between the surface trough and ridging north of the region may support fresh to strong easterly winds north of 20N and west of 130W Mon into Tue. The long period swell will decay below 8 ft south of 20N through early next week, but persist north of 20N due to reinforcing NW swell entering the region. $$ Christensen