000 AXPZ20 KNHC 040737 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 900 UTC Mon Dec 4 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 0830 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough reaches from 10N84W to 07N100W, where it transitions to the intertropical convergence zone and continues to 06N105W to 09.5N115W to 08N123W to beyond 11N140W. Scattered moderate convection is from 10N to 15N between 115W and 120W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of California: Strong high pressure will build well north of the area, over the U.S. Great Basin and northern Rockies through the early part of the week. This will support strong northerly winds over the northern Gulf of California starting this morning, spreading into the central Gulf tonight and early Tue, and the southern Gulf Tue night into Wed. Seas are expected to build up to 10 ft across the north part of the basin by late Tue and to 6- 9 ft across the rest of the basin Wed through Thu. Winds may reach to near gale force over the northern Gulf Mon night and Tue, with strong northeasterly gap winds penetrating across areas in Baja California Norte into the Bay of San Sebastian. The winds will diminish slightly Wed, but will increase again late in the week as reinforcing high pressure builds north of the region, and produce another period of strong to near gale force winds. Gulf of Tehuantepec: Higher pressure north of the area continues to support fresh to strong gap winds through the Gulf of Tehuantepec. Associated seas are 7-9 ft in shorter period swell generated from the strong gap winds reaching 200 to 300 nm downstream of the Gulf of Tehuantepec, mixed with longer period NW swell. The high pressure will weaken through into the morning, allowing for the plume of stronger winds to shrink. Even so, winds will continue to pulse, mainly at night, to fresh to strong through Thu morning, possibly increasing to gale force by late Thu night or early Fri morning as a cold front pushes across the western Gulf of Mexico and through southern Mexico. Looking ahead, strong high pressure building north of the area behind a Gulf of Mexico cold front will 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 NW swell is producing seas of 7 to 9 ft swell propagating across all open waters, except within 100 to 200 nm off the coast south of Los Cabos and the central Mexican coast. The swell will gradually decay to less than 8 ft across all offshore waters by Tue. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Moderate to fresh winds across the Papagayo region will pulse to strong with seas downstream building to 6 to 8 ft Tue and Tue night. Winds and seas diminish through late week as strong trades winds over the southwest Caribbean diminish and veer SE. Looking ahead, strong high pressure will build north of the region, allowing strong gap winds and building seas to reappear by late Sat. Elsewhere, light to gentle N to NE winds are expected N of the monsoon trough, and mainly moderate S to SW winds are expected to the S of the monsoon trough. Seas are in the 4 to 6 ft range, but are expected to build to 5 to 7 ft in SW swell to the S of the monsoon trough, subsiding to 4 to 6 ft through mid week. REMAINDER OF THE AREA... A negatively tilted, mid level short wave trough from 10N to 15N between 120W and 125W is supporting a surface trough along the ITCZ between 115W and 117W. Upper divergence on the southeast side of the trough along with convergence of moderate to fresh trade winds at the surface are supporting scattered moderate convection from 10N to 15N between 115W and 120W. The trough will lift weaken as it lifts W-NW through mid week. An upper low centered near 30N140W continues to support a surface trough reaching from 24N135W to 12N139W. A tight pressure gradient between the trough and high pressure north of the region is supporting fresh to strong easterly winds from 25N to 30N between 130W and 140W. Divergence aloft associated with the upper low is supporting scattered moderate convection from 20N to 25N between 130W and 135W. An earlier scatterometer satellite pass indicated winds to gale force in the area of convection, but this was short lived and has diminished to below gale force as the convection has dissipated. Elsewhere, NW swell greater than 8 ft covers almost the entire discussion waters beyond 250 nm offshore of Central and South America. These seas will gradually decay through the early part of the week. $$ Christensen