000 AXPZ20 KNHC 312158 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...SPECIAL FEATURES... Tropical Storm Lidia is centered near 22.7N 110.1W at 2 pm PDT or just SW of Cabo San Lucas, Mexico moving NNW at 7 kt. Estimated minimum pressure is 991 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Latest satellite imagery shows numerous moderate convection in tightening banding features within 150 nm of the center in the SE semicircle and within 90 nm of the center in the NW semicircle. Scattered moderate isolated strong convection is seen 45 nm either side of a line from 17N108W to 20N107W to 22N107W. Scattered moderate convection is within 60 nm of 18N110W, and along and inland the coast of Mexico from Manzanillo to near Los Mochis. This convection is resulting in very heavy rainfall creating the potential for life- threatening flash floods and mudslides. Very large seas and swells will continue to impact Baja California and the W central coast of Mexico, spreading northward into the Gulf of California. Lidia is forecast to pass near or over the southern tip of the Baja California during the next few hours, then reach near 23.8N 110.7W late tonight with maximum sustained winds 60 kt gusts to 75 kt and move inland across the Baja California peninsula near 25.2N 111.7W early Friday afternoon and begin to weaken. Lidia will continue to weaken as it moves over land to near 26.8N 113.0W late Friday night, then move back over water to near 28.2N 114.4W by early Saturday afternoon with maximum sustained winds of 40 kt gusts to 50 kt. Lidia will continue to weaken and become a remnant low as it continues to the NNW thereafter. Very hazardous marine conditions will continue to impact W Central Mexico and the Baja California Peninsula, spreading northward through the Gulf of California into the upcoming weekend before Lidia weakens. Please see the latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP4/WTPZ24 KNHC for more details, and for the Public Advisory please see the latest NHC forecast/advisory under AWIPS/WMO headers MIATCPEP4/WTPZ34 KNHC. ...TROPICAL WAVES... A tropical wave axis is along 95W N of 11N, moving westward at 10 to 15 kt. Scattered moderate convection is noted to the E of the wave from 10N to 12N between 89W and 91W. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from NW Colombia to 08N78W to 12N94W to 14N105W. It resumes from 15N110W to 13N122W to 13N130W to low pressure at 12N133W 1010 mb to 10N140W. Scattered moderate isolated strong convection exists from 08N to 11N between 97W and 103W, and within 120 nm south of the axis between 110W and 116W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the special features section for information on Tropical Storm Lidia located just S of the southern tip of the Baja California Peninsula. Elsewhere, a ridge axis extends toward the northern offshore waters just W of 120W supporting mainly moderate NW to N flow across the open waters W of the Baja California Peninsula outside of the influence of Lidia. In the Gulf of Tehuantepec, light offshore nocturnal flow is expected through the upcoming weekend and into early next week, 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, pulsing to moderate to fresh Saturday night and Sunday night. The flow is forecast to expand westward over the Pacific waters Sunday night. 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. Seas will be mainly 4 to 6 ft in mixed cross-equatorial southerly swell, as well as some long period NW swell. REMAINDER OF THE AREA... Low pressure of 1010 mb is analyzed at 12N133W. The low is under and area of diffluence aloft. Latest satellite imagery shows enhanced cloudiness and deep convection associated with the low. The convection consists of the scattered strong type intensity within 45 nm of 13N132.5W. Scattered moderate convection is within 120 nm SW quadrant of the low. The low is forecast to remain about stationary through Saturday. The pressure gradient between it and high pressure ridging to its N will maintain moderate NE trades from N of the low to near 19N through at least Saturday. Winds may be locally higher, in the fresh to strong range, in and near the associated convection. Recent altimeter data confirms northerly swells generated from strong winds off the coast of California are propagating into the discussion area N of 30N between 120W and 125W with seas to 8 ft. This swell will subside to less than 8 ft on Friday. Cross-equatorial southerly swell is breaching the equator and will hang around near the equator through the start of the upcoming weekend with seas up to 7 to 9 ft. Another area of southerly swell to 8 ft lingers just S of the monsoon trough thanks to moderate to fresh flow. These seas will subside to less than 8 ft this weekend. Otherwise, weak ridging dominating the waters W of 120W will support moderate to locally fresh trades and 4 to 7 ft through the next several days. $$ Aguirre