000 AXPZ20 KNHC 300936 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 539 UTC Tue Aug 30 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... Lester has begun to weaken and now is a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale. At 30/0900 UTC, it is centered near 18.2N 133.2W or about 1435 MI...2305 KM E of Hilo, Hawaii, moving W or 275 degrees at 12 kt. Estimated minimum central pressure is 956 mb. Maximum sustained winds are 110 kt with gusts to 135 kt. Some weakening is forecast during the next 48 hours. Lester is forecast to cross 140W and move into the central Pacific basin by Wednesday night while continuing on a westward motion. The areal extent of deep convection has decreased since late yesterday, and now satellite imagery shows numerous moderate to strong convection within about 75 NM of the center. Numerous moderate to isolated strong convection is elsewhere within about 90 NM of center, except 120 NM SW quadrant. 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 10N93W to 12N110W to a 1012 mb low pressure near 11N118W to 14N125W. A cluster of moderate to strong convection is from 05N to 08N between 86w and 88.5W. Scattered moderate to isolated strong convection is from 10N to 14N between 86W and 100W. Similar convection is from 11N to 15N between 104W AND 106W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A ridge dominates the waters off Baja California. The pressure gradient between the ridge and the persistent trough meandering along the Baja California peninsula will result in moderate to locally fresh northerly winds and seas generally under 6 ft across the forecast zones off Baja California. Little change in this weather pattern is expected through the end of the week. Marine guidance suggests seas will build close to 8 ft in NW swell across the western part of zone PMZ011 tonight and Wednesday, then subside. Surface troughing over the Baja peninsula will maintain a light and variable wind regime in the Gulf of California through the end of the week with seas generally 2 ft or less. Farther south, winds will be mainly gentle to moderate and WNW with combined seas of 4 to 5 ft. Moderate northerly winds are expected across the Gulf of Tehuantepec early this morning, then a light and variable wind pattern is forecast across this area 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 winds N of it through Friday. Long period cross equatorial SW swell will continue to dominate the area with seas ranging between 4 and 7 ft. REMAINDER OF THE AREA... A broad surface ridge covers most of the northern waters, extending from 1022 mb high pressure near 31N132W. The tail end of a weakening stationary front crosses the NW part of the forecast area and extends from 30N137W to beyond 28N140W. Scatterometer data continue depicting the wind shift associated with this front. Scattered low-topped showers are occurring in the vicinity of this feature. The pressure gradient between the ridge and Lester continues to produce a band of fresh to occasionally strong winds roughly from 20N to 25N between 128W and 135W, with combined seas ranging from 8 to 12 feet. These marine conditions will move westward in tandem with Lester over the next 36-48 hours. Scatterometer data provided observations of fresh to locally strong SW winds S of the monsoon trough and mainly from 09N to 11.5N between 97W and 111W. Seas are 8-9 ft within this area. A pair of weak low pressure centers along the monsoon trough appear to be enhancing these winds. Looking ahead...an area of low pressure could form a few hundred miles south or southwest of the south-central coast of Mexico around the end of the week. Environmental conditions are expected to be conducive for slow development of this system while it moves west-northwestward or northwestward. Currently, the chance of tropical cyclone formation is assessed to be low through 5 days. $$ GR