000 AXPZ20 KNHC 020834 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 834 UTC Sat Dec 2 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 will continue to support gap winds to gale force through this morning with a plume of seas 8 to 12 reaching as far as 240 nm downstream. Another area of seas to 9 ft covers the area from 05N to 12N between 95W and 100W in a mix of NE swell from originating from the gales and longer period NW swell. Winds will gradually diminish to 20 kt or less and seas to less than 8 ft by early Mon as the high pressure weakens. 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 09N85W TO 07N110W where it transitions to the intertropical convergence zone and continues to 11N130W to beyond 09N140W. Scattered moderate convection is from 07N to 10N between 95W and 97W, and from 09N to 14N between 110W and 125W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... An upper level disturbance moving slowly across Baja California Norte this morning will continue eastward into northern Mexico later today, and likely produce scattered light rainshowers and isolated elevated thundershowers across the northern Gulf of California through this morning. 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 couple of days has reached to near 100W, and is producing 6 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 and the Revillagigedo Islands. The swell will 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 will peak near 25 kt during the late night and early morning hours. Seas downstream will build to 6-8 ft during the time of 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. A mid level disturbance near 20N125W will move very slowly ENE through today, and will interact with low level ITCZ moisture to produce active convection to the E and SE of this feature through late today. A cold front NW of the area is closing off a surface low near 32N140W this morning as a short wave mid level trough deepens in the central Pacific. This low will deepen tonight and drift southward, staying west of 140W with associated strong winds. Another mid to upper level disturbance will support the develop of a trough from 10N to 20N between 130W and 140W through early next week. The gradient between the trough and high pressure north of the area will result in fresh to strong easterly winds from 20N and 30N between 130W and 140W with seas to 9 ft early next week. $$ Christensen