000 AXPZ20 KNHC 072135 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2026 UTC Fri Oct 7 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 1800 UTC surface analysis and satellite imagery through 2130 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning...high pressure building southward over eastern Mexico and the Gulf of Mexico will tighten the pressure gradient across the isthmus of Tehuantepec, allowing fresh gap winds which combined with overnight drainage effects will result in string to near-gale force winds overnight. The gradient will tighten even more through Saturday with minimal gale force winds expected Saturday night into Sunday. A cold front will move across the Gulf of Mexico late this weekend which will allow dense, cooler, and drier air to push into the Gulf of Tehuantepec, increasing the winds to 30 to 40 kt Sunday night. Gap winds will diminish slightly thereafter as the airmass to the north modifies and shifts east. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N86W to 11N91W, then resumes from 12N106W to 11N125W to 11N140W. Scattered moderate to strong convection was noted within 240 NM south of the axis between 114W and 118W, and from 10N to 14N between 100W and 104W. Scattered moderate isolated strong convection was noted within 120 NM south of axis between 80W and 100w. Scattered moderate convection was noted elsewhere within 240 NM south of the axis between 105W and 120W, and within 120 NM south of the axis between 128W and 135W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A sub-tropical ridge axis extends from northwest to southeast across the Pacific waters to the Revillagigedo Islands. Strong northerly winds off the coast of California to the north of the region is supporting a surge of northerly swell as far south as 27N between 121W and 125W, impacting the offshore zones off of Baja California Norte. This swell is expected to decay to less than 8 ft tonight, although swell of 5 to 7 ft will persist through Saturday. Otherwise, gentle to moderate northwest to north flow is observed elsewhere across the open Pacific waters west of 110W. The pressure gradient will relax late through today, with the northwest flow diminishing to 5 to 10 kt, and associated seas forecast at 3 to 6 ft everywhere west of 105W by late today. Little change then expected through next Tuesday. Moderate to occasionally fresh northwest winds expected across the Gulf of California north of 30N through early Saturday with seas building to 5 ft. Winds will diminish to a gentle northwest flow by late Saturday and persisting through early next week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light to gentle westerly winds are expected through tonight north of the monsoon trough which is meandering east to west along about 11N, while moderate southwest flow is expected south of the monsoon trough through the upcoming weekend. Winds will become light and variable across the waters north of 11N on Saturday, with little change except moderate easterly flow possible across the Gulf of Papagayo on Sunday night. Combined seas of 3 to 6 ft, primarily in long-period southwest swell, is expected across the offshore waters later in the period from the early to middle part of next week. Fresh trade wind flow is likely between 10N and 15N between the low pressure areas, and the mostly stationary ridge to the north early next week. REMAINDER OF THE AREA... High pressure 1021 mb was centered north of the area near 35N132W will shift southeastward through the next couple of days, ahead of a cold front moving toward the region by early next week. Areas of moderate to fresh trade winds persist north of the monsoon trough to near 20N, with seas of 5 to 7 ft. Global models are in good agreement showing a series of weak low pressure areas forming along the monsoon trough. Although the model depictions differ somewhat in precise locations, there is some general agreement of low pressure forming between 115W and 125W through late Saturday, and there is a moderate chance of tropical cyclone development with this low early next week as it tracks westward along the monsoon trough west of 125W. At any rate, it is plausible there will be areas of 20 to 25 kt winds and seas to 8 ft near this migratory low pressure area. $$ COBB