000 AXPZ20 KNHC 130242 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Thu Oct 13 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 0000 UTC surface analysis and satellite imagery through 0300 UTC. ...SPECIAL FEATURES... A gale warning remains in effect for the Gulf of Tehuantepec for 13/0600 UTC lasting six hours. Recent scatterometer imagery indicated several wind barbs of 30 kt. Winds to minimal gale force are possible with the aid of the nocturnal drainage flow. These winds are a result of a fairly tight surface pressure gradient between high pressure over east central Mexico and lingering lower pressure south of the area in the tropical eastern Pacific. The overall pattern will improve as high pressure north of the area weakens, and 20-25 kt gap winds are anticipated by Friday night. ...TROPICAL WAVE... A tropical wave is along 92W N of 07N. Scattered moderate convection is from 08N to 11N between 91W and 93W. The wave is well depicted in the moisture products and it is forecast to reach the Gulf of Tehuantepec region on Thursday evening. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N85W to 09N91W to 14N100W to 1008 mb low pressure near 12N110W to 10N113W to 14N121W to 13N130W to 11N135W. The ITCZ extends from 11N135W to beyond 09N140W. Scattered moderate to isolated strong convection is from 06N to 11N E of 93W. Scattered moderate convection is from 11N to 14N between 132W and 136W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A ridge extends from 1023 mb high pressure centered north of the area near 31N129W to near the Revillagigedo Islands, supporting gentle to moderate northwest to north winds off the Baja coast with seas of 5-6 ft based on an altimeter pass. These winds will increase to 15 to 20 kt tonight as the ridge builds slightly eastward. The high pressure will weaken Thursday ahead of a frontal boundary moving into the northeast Pacific, allowing the winds to diminish. Looking ahead, long period northwest swell will push into the waters off Baja California Norte by Friday and Baja California Sur Friday night, with building seas of 8-10 ft by early Saturday morning. Winds to 25 kt with seas to 11 ft are possible off the northern portion of Baja California Norte, that includes forecast zone PMZ009,by late Saturday as well as the ridge builds eastward again. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate southwest winds persist south of the monsoon through...including the waters between Ecuador and the Galapagos Islands. Seas are 4 to 6 ft south of the monsoon trough largely associated with long period southwest swell. These marine conditions will change little over the next few days. REMAINDER OF THE AREA... Disorganized showers and thunderstorms are associated with a broad area of low pressure located near 12N110W. Some slow development of this system is possible during the next several days while the low moves west-northwestward at 15 to 20 mph away from the coast of Mexico. The most recent scatterometer data indicate an area of fresh to strong winds within 90 nm N semicircle of low center with seas to 9 ft. Currently, a cluster of moderate to strong convection is within about 360 nm NW quadrant of low center. A second low pressure is centered near 19N128W producing scattered moderate convection within 90 NM N quadrant. The low is about to reach cooler waters, and tropical cyclone formation is not expected while the system moves westward at 10 to 15 mph. Fresh to strong winds are within 300 nm to the north of the center due to the pressure gradient between the low and the ridge to the N. An earlier Ascat pass and a ship observation confirmed the presence of these winds. Seas of 8 to 10 ft are likely to persist as well, although this is in part due to incipient northwest swell already in the area. Elsewhere, a ridge dominates the north waters and is producing mainly gentle to moderate winds across the region outside of the low pressure mentioned above. A new round of long period northwest swell will move into the region tonight, covering the area northwest of a line from 30N121W to 25N125W by early Friday evening, with 8 to 12 ft seas, highest to the northwest. The leading edge of this swell event will reach from Punta Eugenia Mexico to 06N140W by late Friday and from Los Cabos Mexico to the Equator at 136W by Saturday morning. $$ Formosa