000 AXPZ20 KNHC 251619 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Thu Aug 25 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 1200 UTC surface analysis and satellite imagery through 1515 UTC. ...SPECIAL FEATURES... Tropical Storm Lester is located near 16.6N 112.5W at 1500 UTC, or about 155 nm to the south-southwest of Socorro Island, or about 405 nm to the south-southwest of the southern tip of Baja California. Lester is moving WNW or 295 deg at 10 kt with maximum sustained winds of 45 kt gusting to 55 kt. The estimated minimum central pressure is 1002 mb. Lester has strengthened modestly in the past 6 hours, with improved presentation in satellite imagery. Numerous strong convection is occurring within 60 nm across the NW and 45 nm across the SE semicircles, while scattered moderate to strong convection is elsewhere within 120 nm of the center. Lester is producing bands of thunderstorms and strong winds to around 25 kt across the outer waters offshore of Cabo Corrientes this morning, with seas 8-10 ft. Lester is expected to continue moving west-northwest and away from the Mexican offshore waters tonight as it gradually strengthens to a hurricane by Friday morning. Please read the NHC forecast/advisory under AWIPS/WMO headers MIATCMEP3/WTPZ23 KNHC or the public bulletin under MIATCPEP3/ WTPZ33 KNHC for more details. A broad tropical wave is moving along the monsoon trough in the vicinity of 129W-131W, moving westward near 15 knots. A 1008 mb low pressure center is suggested near 11.5N129W. Scattered to numerous strong convection has developed in recent hours within 360 nm across the NW semicircle, while scattered moderate to strong convection was elsewhere along the monsoon trough within 120 nm of the center. Fresh NE trade winds cover the area from 13N to 19N from 124W westward, where seas are running 6-9 ft. Environmental conditions are conducive for continued gradual improvement in organization of this system. It has a medium chance for tropical cyclone development during the next 48 hours before crossing 140W by 72 hrs. ...TROPICAL WAVES... No additional waves at this time. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N74W to 08N79W to 09N85W to 10N106W. Scattered to numerous moderate to strong convection is noted from 05N to 08N east of 88W...and within 150 nm south ofthe trough between 93W and 110W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A narrow surface ridge extends from the NE Pacific southeastward through 30N129W to north of Lester near 21N113W. This ridge will change little through the upcoming weekend, and combine with the persistent trough meandering along the Baja California peninsula and Gulf of California, to produce mainly light to moderate northerly flow prevailing outside of the Gulf of California. Expect mainly light to gentle southerly flow In the Gulf of California, except for occasionally fresh wind flow in the northern Gulf where the pressure gradient will be slightly tighter. High pressure in the Gulf of Mexico continues to drive 20-30 kt northerly winds across the Gulf of Tehuantepec where seas have built to 6-10 ft. These winds and seas will diminish modestly today and persist through tonight before falling to less than 20 kt by Friday afternoon. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to locally fresh offshore winds are expected across most of the area east of 95W and north of the monsoon trough today through the early afternoon hours. Global models suggest that a weak surface trough will develop just east of the Gulf of Tehuantepec by tonight and help to draw the southwesterly winds occurring south of the monsoon trough northward into these coastal areas. A light and variable onshore flow is thus expected to prevail through the weekend. ELSEWHERE... A broad surface ridge covers the remainder of the area, extending from a large 1036 mb high near 49N142W. The low pressure center that is along 129W and its associated tropical wave will move westward during the next few days. The pressure gradient between this lower pressure and the ridge will yield fresh winds across the trade wind belt, generally from 21N southward to near the trough, from just to the northeast of the low center to beyond 140W. Sea ranging from 6 feet to 8 feet in this area in mixed swell will increase slightly to 7 to 9 feet during this time. A large area of fresh southwesterly monsoonal flow is supporting seas of 6 to 8 feet from 07N northward between 115W and 125W. The strength and areal coverage of these fresh winds will increase to the south and southeast of the low center as it shifts westward during the next few days. $$ Stripling