000 AXPZ20 KNHC 030816 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 630 UTC Sun Dec 3 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. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monoon trough extends from Monsoon Trough extends from 07N74W to low pres near 06N78W to 08N85W TO 05.5N94W to low pres near 08N110W TO 08N115W, where it transitions to ITCZ, and continues on to 09N120W TO 09N131W TO beyond 09.5N140W. Scattered to locally numerous moderate to strong convection is occurring from 07N to 13N between 106W and 116W. Scattered moderate isolated strong convection is from 10N to 17.5N between 117W and 130W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Higher pressure north of the area continue to support fresh to strong gap winds through the Gulf of Tehuantepec. Associated seas including shorter period swell generated from the strong gap winds reach 200 to 300 nm downstream of the Gulf of Tehuantepec, mixed with longer period NW swell. The high pressure weakens through tonight, allowing winds to diminish below 20 kt and seas to subside below 8 ft by late Mon, with minor pulse to 25 kt again Mon night due to local drainage flow. Strong gap winds return by Tue night, possibly increasing to gale force by late Wed due as a cold front pushes across the western Gulf of Mexico and through southern Mexico. Looking ahead, strong high pressure builds north of the area behind the front, supporting a persistent strong gale event across the Gulf of Tehuantepec through late in the week. Elsewhere off the Pacific coast of Mexico, weak high pressure is maintaining gentle to moderate breezes across the region. Long period 8 to 10 ft swell is propagating across all open waters, except within 150 nm of the coast south of Los Cabos. The swell will gradually decay below 8 ft in all offshore waters by Tue. For the Gulf of California, strong high pressure will build well north of the area, over the Great Basin and northern Rockies early next week. This will support strong NW winds over the northern Gulf of California by early Mon, spreading into the central Gulf Mon night and early Tue, and the southern Gulf Tue night into Wed with seas to 9 ft. Winds may reach near gale force over the northern Gulf late Tue, with strong easterly gap winds penetrating across areas in Baja California Norte into the Bay of San Sebastian. The winds will diminish slightly Wed, but increase again late in the week as reinforcing high pressure builds north of the region. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh to strong offshore gap winds across the Papagayo region will peak to 25 kt during the late night and early morning hours through Monday. Seas downstream from the gulf will build to 6-8 ft during the time of peak winds, subsiding slightly each afternoon and evening. Elsewhere, light to gentle N to NE winds are expected north of the monsoon trough and mainly moderate S to SW winds are expected to the south of the monsoon trough. Seas are in the 4-6 ft, but are expected to build to 5-7 ft in a SW swell to the south of the monsoon trough beginning on Sunday afternoon and into Monday. 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 100W. 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. Very Active convection is occurring near and north of the monsoon trough between 106W AND 116W, where a 1007 mb low pressure is along the trough near 08N110W. 20-30 kt E winds across the N portions of the low are kicking up wind waves that are combining with the NW swell moving through the regional waters to produce seas of 10-13 ft. A cold front remains across the NW corner of the area from 30N138.5W TO 26N140W this evening, and is connected to a 1010 surface low near 31N141. This low will deepen tonight and drift generally southwestward, staying to the west of 140W with associated gale force winds. Another mid to upper level disturbance will support the development of a trough near a position from 19N137W TO 24N134W by Sunday afternoon. The gradient between the trough and high pressure to the north of the area will result in fresh to strong easterly winds from 20N and 30N between 130W-140W with seas building to 8-11 ft through early next week as the trough slowly moves westward. $$ Christensen