000 AXPZ20 KNHC 041522 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1522 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Gulf of California: Strong high pressure is building well N of the area over the U.S. Great Basin and northern Rockies, supporting the development of fresh to strong NW flow in the far northern Gulf. Winds will increase to minimal gale Tue morning in the northern Gulf as the pressure gradient continues to tighten, then will diminish below gale by Tue evening as it slackens slightly. Meanwhile, the fresh to strong winds will spill southward across the entire Gulf by mid-week. Seas are expected to build up to 10 ft across the northern part of the basin by late Tue and to 6 to 9 ft across the remainder of the basin Wed through Thu. Also, strong northeasterly gap winds will be penetrating across areas in Baja California Norte into the Bay of San Sebastian. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from low pressure near 06N78W to 08N83W to 07N102W. The intertropical convergence zone axis extends from 07N102W to 10N117W, then resumes from 10N120W to 08N130W to 12N140W. Scattered moderate and isolated strong convection is within 120 nm in the NW semicircle of the low near 06N78W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 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 to 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 Wed night as a cold front pushes across the western Gulf of Mexico and through southern Mexico. Looking ahead, strong high pressure building N 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 through the remainder of the morning and again tonight. Winds and seas will diminish through late week as strong trades winds over the southwest Caribbean diminish and veer SE. Looking ahead, strong high pressure will build N of the region, allowing strong gap winds and building seas to reappear by late Sat. Winds may even approach minimal gale force late Sat night through early Sun. 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 125W. Upper divergence on the SE side of the trough along with convergence of moderate to fresh trade winds at the surface are supporting scattered moderate to strong convection within an area bounded by 13N122W to 17N117W to 17N110W to 05N116W to 13N122W. The trough will lift weaken as it lifts W-NW through mid week. An upper low centered near 31N139W continues to support a pair of surface troughs, one from 26N136W to 21N136W, and a second from 20N136W to 14N140W. Scattered moderate and isolated strong convection covers much of the waters N of 10N W of 120W thanks to divergence aloft associated with the upper low. A tight pressure gradient between the troughs and high pressure N of the region is supporting fresh to strong easterly winds on the eastern periphery of the troughs. 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. $$ Lewitsky