000 AXPZ20 KNHC 280939 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Sun Aug 28 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... Hurricane Lester is centered near 17.9N 122.2W at 28/0900 UTC moving west or 270 degrees at 12 kt. Estimated minimum central pressure is 978 mb. Maximum sustained wind speed is 85 kt with gusts to 105 kt. Little change in strength is expected today, but slow weakening should begin by Monday. Numerous moderate scattered strong convection is within about 75 nm of center. Scattered moderate convection is noted elsewhere within about 90 nm of center. Lester will continue on a general westward motion, with an increase in forward speed during the next couple of days. 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 11N90W to 12N102W to low pressure near 10.5N111W to 12N114W. Scattered moderate isolated strong convection is from 09N to 13N between 111W and 116W. Scattered moderate convection can be found from 10N to 12.5N between 105W and 108W. ...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 over the next 48 hours. By Tuesday night, marine guidance suggests building seas to 8-9 ft in NW swell across zone PMZ011 and regional waters. Expect light and variable winds in the Gulf of California through the next several days. In the Gulf of Tehuantepec, moderate to occasionally fresh northerly winds and seas of 4-6 ft are expected during the overnight and early morning hours through Tuesday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light and moderate winds will continue to prevail on either side of the monsoon trough for the next several days, with combined seas of 4 to 7 ft mainly in cross equatorial southerly swell. ELSEWHERE... Tropical Storm Madeline has crossed into the central Pacific basin. At 28/0900 UTC, Madeline is centered near 16.1N 140.6W moving NW or 305 degrees at 7 kt. Estimated minimum central pressure is 998 mb. Maximum sustained wind speed is 50 kt with gusts to 60 kt. Fresh to strong winds in the 20-30 kt range and seas up to 14-16 ft, associated with Madeline, continue to affect the west- central waters, particularly from 14N to 17N W of 138W. Winds will gradually diminish today into Monday as Madeline continues to move away from the forecast area. However, seas will briefly subside through Monday, then increase again as tropical cyclone Lester approaches the west-central waters. A broad surface ridge covers most of the north waters, extending from 1021 mb high pressure near 31N130W. A weak surface trough extends from 28N136W to 20N139W, and will cross 140W tonight. The 0614 UTC Ascat pass shows the wind shift associated with the trough S of 26N. Isolated showers and thunderstorms are associated with 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 6 to 9 feet. A weak low pressure of 1012 mb remains embedded in the monsoon trough near 10.5N111W. Scattered moderate isolated strong convection is noted mainly west of the center from 09N to 13N between 111W and 116W. 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 west of the low pressure. Marine guidance suggests fresh to strong SW to W winds mainly S of the low center from 08N to 11N between 110W and 117W tonight through Monday night, with seas building to 8 to 10 ft on Monday. $$ GR