000 AXPZ20 KNHC 011527 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: High pressure north of the area supports a tight pressure gradient and wind pulses to gale force across the Gulf of Tehuantepec through Saturday morning. Max seas are reaching 13-14 ft, with seas to 8 ft extending 650 nm downstream WSW of the source region, with the NE wind waves mixing with longer period NW swell. Seas will subside to 8 to 10 ft by Sunday. Winds will diminish to less than 20 kt with seas subsiding to less than 8 ft by early Monday. Another gale event may develop mid-week as a strong cold front moves into the Gulf of Mexico and southern Mexico. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N84W to 07N102W, where it transitions to the ITCZ, which continues to 08N140W. Scattered moderate convection is noted within 120 nm north of the ITCZ W of 121W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see Special Features section for details about a gale warning in the Gulf of Tehuantepec. An upper level disturbance will bring isolated showers to the northern Gulf of California through Sat. Weak ridging over the region will support gentle to moderate northerly winds across the area into early next week. Long period NW swell propagating across the waters offshore of Baja California the past 2 days has reached to near 105W, and is producing 6 to 9 ft seas from Baja California Sur to south of Manzanillo. Reinforcing NW swell moving into the waters off Baja California Norte is producing 8 to 13 ft seas. This swell will reach the Revillagigedo Islands at 10 ft by early Sat, then slowly decay below 8 ft by late Mon. High pressure building in the wake of a cold front moving across the SW U.S. Sunday night through Monday night will induce strong NW winds through the length of the Gulf of California Monday and 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 a high over the western Gulf of Mexico and lower pressure in the southwest Caribbean is producing fresh to occasionally strong offshore gap winds across the Papagayo region. Winds are enhanced by diurnal drainage effects, peaking near 25 kt during late night and early morning hours. Seas downstream will build to 6-8 ft during peak winds, diminishing slightly each afternoon and evening. Elsewhere, light to gentle N to NE winds and 4-5 ft seas are expected through Saturday north of the monsoon trough. Moderate S winds and 4-6 ft seas are forecast south of the trough axis. REMAINDER OF THE AREA... A large area of long period NW swell producing seas of 8-12 ft will continue to propagate across the region west of 110W. The swell will decay south of 20N through next week, but persist north of 20N due to reinforcing NW swell entering the region. High pressure near 32N137W supports fresh winds north of 15N and west of 125W, and enhancing fresh to strong trade winds between 10N and 15N west of 130W. Winds will diminish tonight as the ridge weakens. A mid level disturbance near 20N120W will persist through Sat. A cold front NW of the area is expected to close off a surface low near 32N140W in about 24 hours as a short wave mid level trough deepens in the central Pacific. This low will deepen Sat night near 30N140W and create a tight gradient and near gale force winds north of the low center. This is expected to produce an area of 10-14 ft sea in the NW part of the forecast area in about 36 hours. The low will drift SSW and weaken Sunday, with associated seas subsiding to 8-10 ft by early Mon. $$ Mundell