000 AXPZ20 KNHC 310854 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 854 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 0600 UTC surface analysis and satellite imagery through 0830 UTC. ...SPECIAL FEATURES... Tropical Storm Lidia is centered near 21.3N 109.4W at 31/0900 UTC or about 100 nm SSE of Cabo San Lucas, Mexico moving NNW at 7 kt. Estimated minimum pressure is 997 mb. Maximum sustained wind speed is 40 kt with gusts to 50 kt. Numerous moderate and isolated strong convection is within 210 nm in the NE quadrant, within 150 nm in the SE and NW quadrants, and also within 180 nm in the SW quadrant. 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 strengthen through early Fri as it continues to approach the southern tip of Baja California, then is forecast to weaken as it continues to the NNW along or inland over the Baja California peninsula, becoming a remnant low by early Sun. Please see the latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP4/WTPZ24 KNHC for more details. ...TROPICAL WAVES... A tropical wave is N of 10N along 91W moving W at 10 to 15 kt. Scattered moderate and isolated strong convection is N of 10N E of 90W, including across the Gulfs of Fonseca and Papagayo. Model guidance indicates that the tropical wave may catch up to a developing area of low pressure near 12N101W by early Sat. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N78W to 11N90W to 16N106W, then resumes from 17N110W to 14N121W to low pressure near 12N134W to 00N140W. Scattered moderate and isolated strong convection is within 180 nm SE of the monsoon trough axis between 107W and 117W. In addition, scattered moderate and isolated strong convection is within 120 nm W of a line from 06N103W to 18N103W. This convection may be associated with the remnants of a tropical wave, enhanced by deep southerly flow around the outer circulation of Lidia. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the special features section for information on Tropical Storm Lidia located 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 Sat night and Sun 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... A nearly stationary 1010 mb low center is analyzed along the monsoon trough near 12N134W. Scattered moderate and isolated strong convection is within 180 nm in the NE quadrant and 150 nm in the SW quadrant of the low. This low is forecast to linger and change little during the next few days. Farther N, northerly swells generated from strong winds off the coast of California are beginning to propagate into the discussion area N of 29N between 121W and 126W, as measured by earlier altimeter passes which showed seas near 8 ft. This swell will subside by the start of the upcoming weekend. 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. $$ Lewitsky