000 AXPZ20 KNHC 200956 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 917 UTC Sun Nov 20 2016 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: Impressive high pressure ridging continues to surge southward along eastern Mexico while a strong cold front pushes through the southwest Gulf of Mexico. Gale to near storm force winds are howling out of the north early this morning and will persist through the day and tonight. Winds will diminish below gale force Monday afternoon, although another gale force wind event is anticipated Wednesday night through at least the end of the week. Seas will build to 20 to 24 ft with the persistent and strong winds through early Monday. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N79W to 06N100W. The intertropical convergence zone axis extends from 06N100W to low pressure near 09N125W to 10N140W. Scattered moderate convection is from 07N to 09N between 82W and 89W, and also from 08N to 10N between 109W and 113W. Scattered moderate convection is from 14N to 18N between 116W and 121W, under an area of upper level diffluence. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the special features section for information on the gale warning in the Gulf of Tehuantepec. In the Gulf of California, scatterometer data showed moderate to fresh northwest flow while an altimeter pass sampled 1 to 3 ft seas. Low pressure is forecast to develop along a trough in the northern gulf tonight which will precede an approaching cold front. Winds will become southerly in the northern gulf on the southeast side of the low, increasing to 20 to 30 kt this evening. Seas will build up to 8 ft as a result of the winds. The cold front will move across the northern gulf Monday afternoon and night while weakening, with winds shifting to the north behind it. A tight pressure gradient will develop across the region by Thursday, and northwest flow will increase to 20 to 30 kt west of 110W for the end of the week with seas building up to 8 ft. Elsewhere, northwest swell continues to decay, with combined seas at 4 to 7 ft, the highest of which can be found in the vicinity of the Revillagigedo Islands. A cold front will move into the area from the northwest late tonight through Monday. Seas will build to 8 to 11 ft from northwest to southeast today through the early part of the week. As mentioned above, the pressure gradient will tighten across the region Thursday, and northwest winds offshore of Baja California Norte will increase to fresh to strong. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... In the Gulf of Papagayo, moderate to locally fresh offshore winds will increase to fresh to strong in the next few hours as a persistent cyclonic circulation in the western Caribbean Sea combines with strengthening high pressure ridging over Central America. The fresh to strong northeast winds will persist through Tuesday before diminishing. Winds will also briefly pulse to fresh to strong offshore of the Gulf of Fonseca tonight. Elsewhere, light to gentle northerly winds and combined seas of 3 to 5 ft are occurring north of the monsoon trough, which continues to meander from east to west along about 09N, while moderate to locally fresh southwest flow is observed south of the monsoon trough, with combined seas of 3 to 5 ft primarily in long-period southwest swell. Little change is forecast through the start of the upcoming week. REMAINDER OF THE AREA... A cold front is sweeping across the northern waters, currently analyzed from 30N125W to 22N140W. Associated winds greater than 20 kt are found just north of the discussion waters, while northwest swells of 8 to 15 ft, highest along 30N, continue to propagate to the southeast. The front will weaken as it continues across the northern waters, with the swell beginning to outrun the boundary itself. High pressure will quickly build in the wake of the front, which will tighten the pressure gradient, especially across the west- central waters. Trades will then increase to fresh to strong southwest of the ridging later today through the week. A new cold front will drop into the northern waters by the end of the week ushering in a reinforcing set of northwest to north swell. $$ LEWITSKY