000 AXPZ20 KNHC 290943 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 658 UTC Mon Aug 29 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 0900 UTC. ...SPECIAL FEATURES... Lester makes a comeback and becomes a major hurricane. At 29/0900 UTC, it is centered near 18.0N 127.8W moving west or 270 degrees at 13 kt. Estimated minimum central pressure is 965 mb. Maximum sustained wind speed is 100 kt with gusts to 120 kt. Lester is a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale. Little change in strength is expected today, but slow weakening is expected to begin by Tuesday. Lester is forecast to cross 140W and move into the central Pacific basin by Wednesday night while continuing on a westward motion. Numerous moderate to strong convection is seen within 75 NM of center. Numerous moderate to isolated strong convection is elsewhere within 120 nm of center. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP3/WTPZ23 KNHC for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N90W to low pressure near 12N113W to 13N120W. A cluster of moderate to strong convection is near 07.5N83W. Scattered moderate and isolated strong convection is within 75 nm of the coast of Central America between 85W and 90W. Scattered moderate convection is from 09N to 11N between 96W AND 99W, and from 09N to 11N between 104W AND 106W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A ridge dominates the waters off Baja California producing moderate to locally fresh northerly winds and seas generally under 6 ft. Little change in this weather pattern is expected through Tuesday. By Tuesday night into Wednesday, marine guidance suggests building seas to 8 in northwest swell across the western part of zone PMZ011. Expect light and variable winds in the Gulf of California through the next several days with seas of 2 ft or less. Farther south, winds will be mainly gentle to moderate and west-northwest with combined seas of 4 to 6 ft. Pulsing moderate to locally fresh northerly winds are expected across the Gulf of Tehuantepec during the overnight and early morning hours through Thursday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate SW winds will prevail S of the monsoon trough with mainly light to gentle variable winds N of it. Long period cross equatorial SW swell will continue to dominate the area with seas of 4 to 7 ft. REMAINDER OF THE AREA... Hurricane Madeline is west of 140W, however, winds of 20 to 25 kt and seas to 9 ft continue to impact the area from 15N to 19N W of 138W. These marine conditions will gradually diminish over the next 12 hours as Madeline continues to move farther west of the area. Seas generated by hurricane Lester will reach the west- central waters later today. A broad surface ridge covers most of the northern waters, extending from 1023 mb high pressure near 33N130W. A weak surface trough persists across the NW part of the forecast area and extends from 30N136W to beyond 24N140W. A recent Ascat pass continues to show the wind shift associated with this trough. Scattered showers and isolated thunderstorms are occurring in the vicinity of this feature. The pressure gradient between the ridge and Lester will produce a band of moderate to fresh winds roughly from 20N to 25N, with combined seas ranging from 9 to 12 feet. Weak low pressure of 1010 mb remains embedded in the monsoon trough near 12N113W. Convection has increased in association with this system over the past 24 hours. Satellite imagery shows scattered moderate to isolated strong convection from 10N to 13N between 112W and 115W. Tropical cyclone formation is forecast to remain low through the next several days as it tracks westward along the monsoon trough. Scatterometer data show moderate to fresh southwesterly monsoon flow into the monsoon trough south of the low pressure. Marine guidance suggests that an area of fresh to strong southwest to west winds will persist S of the low center over the next 48 hours, with seas building to 8 to 10 ft by Tuesday night. $$ GR