000 AXPZ20 KNHC 012204 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Fri Dec 01 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: High pressure north of the area supports a tight pressure gradient across the Isthmus of Tehuantepec and pulsing gale force northerly across the Gulf of Tehuantepec today, with gales expected to continue through Saturday morning. Max seas this afternoon are 11-2 ft and will increase to 13-14 ft early Saturday morning during peak winds of 35-40 kt. The resultant plume of N to NE winds extending downstream of the gulf will produce an area of seas to 8 ft and greater extending 650 nm downstream SW of the gulf. Seas will subside to 8 to 10 ft by Sunday as winds gradually diminish to 20-30 kt. Winds will diminish to less than 20 kt with seas subsiding to less than 8 ft by early Monday. Another gale event is expected to 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 09N75W to 07N98W, where it transitions to the ITCZ, which continues to beyond 07N140W. Scattered moderate convection is noted from 06N to 09N between 77W and 84W, and from 06N to 10N between 93W and 110W. Scattered moderate to strong convection is noted from 08N to 18N between 112W and 133W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... An upper level disturbance moving onshore across Baja California Norte this afternoon and tonight will bring scattered showers and isolated elevated thundershowers 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 102W, and is producing 7 to 10 ft seas across the offshore waters of north and central portions of Baja California, and 5 to 9 ft seas from Baja California Sur to south of Manzanillo. 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 entire 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. Please see Special Features section for details about the gale warning in the Gulf of Tehuantepec. 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 far 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 being enhanced by diurnal drainage effects, and 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 to less than 8 ft south of 20N through next week, but persist at 8 ft and greater north of 20N due to reinforcing NW swell entering the region. High pressure near 31N135W supports fresh winds north of 15N and west of 125W, and is enhancing fresh to strong trade winds between 10N and 20N west of 130W. Winds will diminish tonight as the ridge weakens. A mid level disturbance near 20N126W 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 just to the W of 30N140W and create a tight pressure gradient and near gale force winds north of the low center. This is expected to produce an area of 10-14 ft seas 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. $$ Stripling