000 AXPZ20 KNHC 051533 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1533 UTC Tue Dec 5 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 currently building from the U.S. Great Basin and northern Rockies southward towards the desert SW of the U.S., and supports near gale to gale force NW winds in the far northern Gulf N of 30N. Fresh to strong NW winds extend as far S as 28N. The gale-force winds are expected to diminish below gale this evening as the pressure gradient relaxes somewhat. Meanwhile, the fresh to strong winds will continue to spill southward across the entire Gulf through Wed night. Another area of strong high pressure will build across the region Wed night through Thu and is expected to initiate another round of gales across N and north-central portions Thu. Seas are expected to build up to 9 ft across the northern part of the basin today and to 6 to 9 ft across the remainder of the basin Wed through Thu. Also, as the strong winds develop across the Gulf, strong northeasterly gap winds will bleed through gaps in the mountain peaks across the northern peninsula and spill across the Bay of San Sebastian. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 08N82W to 08N96W. The ITCZ extends from 08N96W to 07N110W to 11N123W to 08N140W. Widely scattered moderate convection is N of 05N E of 81W. Scattered moderate convection is from 07N to 17N between 122W and 127W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: The effects of overnight residual drainage effects are allowing moderate to fresh gap winds early this morning. These winds will gradually diminish by the early afternoon, but will pulse again to 20 to 25 kt tonight. Winds will increase to fresh to strong late Wed ahead of a cold front moving across the western Gulf of Mexico, arriving in southern Mexico Thu. Winds will further increase to minimal gales by Thu night as the cold and dry air pushes into the Gulf of Tehuantepec. Seas will build to 15 ft by early Fri, with seas 8 ft or greater reaching as far as 500 nm downstream to the W-SW of the Gulf of Tehuantepec. Looking ahead, strong high pressure building behind the front across central Mexico will support 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 to 9 ft is noted beyond 120 nm off Baja California in recent altimeter satellite passes. This swell will subside below 8 ft through late today. High pressure building north of area will result in strong gap winds pushing across low lying areas of Baja California Norte and into adjacent waters Thu. A larger plume of strong NE winds will push off the coast of Baja California Sur north of Cabo San Lazaro Thu night and Fri, with seas 8 to 10 ft reaching beyond 250 nm offshore. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Moderate to fresh NE winds across the Papagayo region will persist with seas downstream maintaining a range of 6 to 8 ft. Winds and seas will diminish likely Thu as strong trades winds across the SW Caribbean Sea diminish and veer SE. Looking ahead, strong high pressure will build N of the region, allowing strong gap winds and building seas to reappear late Sat night into Sun. Winds may even approach minimal gale force Mon. Elsewhere, light to gentle N to NE winds are expected N of the monsoon trough, and mainly gentle to moderate S to SW winds are expected to the S of the monsoon trough. Seas are in the 5 to 7 ft range in SW swell this evening to the S of the monsoon trough, and will subside to 4 to 6 ft through mid week. REMAINDER OF THE AREA... An upper level short wave trough noted on water vapor imagery in the vicinity of 30N135W continues to lift N of the area today. This troughing supports a 1010 mb complex surface low centered near 28N136W. Overnight scatterometer passes indicated 20 to 30 kt easterly winds between 25N and 30N between 130W and 139W, between the complex low pressure area and high pressure north of the area. Seas are 8 to 14 ft in this area, due in part to lingering long period NW swell. Divergence aloft to the E of the upper level trough is generating scattered showers and tstms from 07N to 27N between 121W and 132W. Residual fresh to strong SE to S winds will persist through late Wed N of 27N between 130W and 140W as the upper support lifts north, and ahead of a cold front approaching the area from the W-NW. Scattered showers and a few tstms will persist in this area as well. The next cold front will approach the NW corner of the discussion area Wed, stall along 141W and then dissipate just NW of the discussion area early Fri. Looking ahead, strong southerly flow will return Sat N of 28N W of 135W ahead of yet another cold front approaching from the NW. Elsewhere, long period swell to 9 ft persisting across much of the area south of 20N will decay below 8 ft through Fri. A new round of NW swell to 9 ft will propagate into the discussion area, encompassing the region N of 15N W of 130W by Thu, then most of the area W of 120W by late Fri into Sat, mixing with shorter period NE waves N of 20N and E of 125W. $$ HUFFMAN