000 AXPZ20 KNHC 310239 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Thu Aug 31 2017 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 0215 UTC. ...SPECIAL FEATURES... Tropical Storm Lidia is centered near 20.7N 109.2W at 31/0300 UTC or about 150 nm SSE of the southern tip of Baja California moving NNW at 6 kt. Estimated minimum pressure is 1001 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Last visible satellite imagery showed that banding features are were becoming more consolidated around the cyclone. The imagery reveals numerous strong convection within 90 nm of the center in the SE quadrant. Scattered moderate to strong convection exists from 16N to 21N between 105W and 108W. Scattered moderate isolated strong convection is within 45 nm either side of a line from 14N115W to 15N109W, and also within 30 nm either side of a line from 13N105W to 16N103W. An Ascat pass from 1706 UTC Wednesday afternoon revealed a swath of fresh to strong E to SE winds to the E and SE of now Tropical Storm Lidia from about 15N to 21N between the coast of Mexico and 108W. Lidia is forecast to reach near 21.6N 109.5W early Thursday with maximum sustained winds of 45 kt gusts to 65 kt, and strengthen some as it continues to just south of Los Cabos near 22.8N 110.0W by early Thursday evening with maximum winds of 55 kt gusts to 55 kt. Lidia is then forecast to move inland over Baja California Sur Thursday night and begin to weaken as it reaches near 23.8N 110.6W early Friday with maximum sustained winds of 45 kt gusts to 55 kt, and to near 25.5N 111.7W by early Friday evening with maximum sustained winds of 40 kt gusts to 50 kt. Lidia is then forecast to track NW across central Baja California through reaching to just NE of Punta Eugenia by Saturday night as it continues to weaken. Large and dangerous swells will impact the coast of SW and western Mexico, and either sides of the Baja California Peninsula, with dangerous and life-threatening rainfall forecast across the Mexican states of of Baja California Sur, western Jalisco, Sinaloa, Nayarit, Colima, southern Michoacan, southern Sonora and central Jalisco. The greatest potential rainfall accumulations are expected to be over Baja California Sur and western Jalisco. Please see the latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP4/WTPZ24 KNHC for more details. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from NW Colombia to across central Costa Rica to 10N86W to 11N95W to 16N104W. It resumes at 17N112W to 12.5N124W to low pressure near 11N134W 1010 mb to 10N140W. Scattered moderate isolated strong convection is within 30 nm of axis E of 87W. Scattered moderate convection is within 120 nm south of axis between 100W and 104W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the special features section for information on Tropical Storm Lidia located W of central Mexico. A ridge axis extends toward the northern offshore waters just W of 120W supporting gentle to moderate NW flow across the open waters W of the Baja California Peninsula. Winds in the Gulf of California are currently light and variable with seas 2 ft or less, except 4 to 6 ft near the entrance. Conditions at the entrance to the Gulf of California, and over the southern portion of the Gulf will drastically begin to worsen as Potential Tropical Cyclone Fourteen-E approaches. In the Gulf of Tehuantepec, light offshore nocturnal flow is expected this week and the upcoming weekend, with light to gentle onshore flow during the day. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... In the Gulf of Papagayo, gentle offshore nocturnal flow is expected through the remainder of the week, becoming gentle to moderate this weekend. Otherwise, light and variable flow is expected N of the monsoon trough, while moderate to locally fresh southerly winds are expected S of the monsoon trough. Long period southerly cross- equatorial swell, in the form of 5 to 7 ft seas will gradually subside through late this week. REMAINDER OF THE AREA... A nearly stationary 1010 mb low center is analyzed along the monsoon trough near 11N132W. Another low 1010 mb low is analyzed near 11N134W. An Ascat pass from 1848 UTC Wednesday afternoon indicated moderate to fresh NE winds to the N of the low near 11N132W from 11N to 15N between 132W and 133W, and to the S of the same low from 10N to 11N between 131W and 133W. Small clusters of scattered moderate convection are present within 30 nm of 12N131W and within 30 nm of 12.5N133W. These lows are expected to change little through Friday. Farther north, northerly swell generated from strong winds off the coast of California are forecast to begin to propagate into the discussion area south of 32N between 124W and 127W tonight with combined seas to 8 ft, then decaying below 8 ft through Thu. Also, cross-equatorial southerly swell will breach the equator building seas to 7 to 9 ft S of the monsoon trough between 120W and 135W through the early part of the upcoming weekend. Otherwise, weak ridging dominating the waters W of 120W will support moderate to locally fresh trades and 4 to 7 ft seas through the remainder of the week and the upcoming weekend. $$ Aguirre