000 AXPZ20 KNHC 260922 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 922 UTC Sat Aug 26 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 0900 UTC. ..TROPICAL WAVES AND TROPICAL LOWS... A tropical wave is analyzed to the N of 11N along 92W moving W at 10 to 15 kt. Scattered moderate and isolated strong convection is within 240 nm W of the tropical wave axis. Model guidance continues to suggest that a surface low will develop along this wave near 14N101W on Sun. The low will then continue to move NW passing to the S of the Baja California Peninsula during the middle of next week. A tropical wave is analyzed from low pressure near 13N107W to 20N108W moving W at around 5 kt. Scattered moderate and isolated strong convection is within 360 nm in the S semicircle of the low. This tropical wave will continue to move very slowly while becoming less defined over the next day or so. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from low pressure near 10N75W to 11N90W to low pressure near 13N107W to 12N120W to 11N130W to 12N140W. Scattered moderate and isolated strong convection is from 08N to 12N between 113W and 118W, and also from 08N to 11N between 130W and 133W. Scattered moderate convection is from 06N to 08N between 94W and 99W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A NW to SE oriented low level trough will meander from E to W across the Baja California Peninsula and Gulf of California through the weekend with a weak surface low developing intermittently along the central portion of the Gulf of California waters. A NW to SE oriented ridge extends across the open EPAC waters beyond 250 nm. The resultant pressure gradient will support a moderate NW breeze W of the Baja California Peninsula through Sun evening, except becoming fresh during the evenings within about 90 nm of the Pacific Coast of Baja California. Expect 3 to 6 ft seas throughout these waters this weekend. A weak cold front will move SE across the Baja Peninsula and Gulf of California on Mon afternoon, and stall and wash out along 28N on Mon night into Tue. Otherwise in the Gulf of California, scattered moderate to strong convection is from 21N to 26N within 30 nm of the mainland due to late afternoon and evening convection that developed over nearby topography. Light to gentle southerly flow will persist this weekend, except a brief moderate southerly breeze will develop intermittently across the northern Gulf waters. A gentle to brief moderate NW breeze will follow the cold front on Mon evening. In the Gulf of Tehuantepec, light to gentle N drainage winds are forecast through early next week during the overnight hours, with gentle onshore flow during the day. Elsewhere, fresh to strong southwesterly monsoon flow and long period cross-equatorial swell, in the form 7 to 10 ft seas, will arrive across the waters S of 18N and W of 96W by early Sun. By then a surface low is forecast to develop along the northern extension of a tropical wave in the vicinity of 14N101W on Sun. The low will continue to move NW passing to the S of the Baja California Peninsula during the middle of next week. A band of fresh to locally strong southerly flow is forecast to develop within about 390 nm E of the low, and these conditions will shift NW across the Mexican offshore waters between 105W and 112W through Thu. Extended guidance hints at favorable conditions for this low to deepen. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... In the Gulf of Papagayo, moderate to fresh offshore flow is forecast tonight through Sunday morning. Otherwise, light and variable flow is expected N of the monsoon trough through the middle of next week, while moderate to locally fresh southerly winds are expected S of the monsoon trough axis. Long period southerly cross-equatorial swell, in the form of 7 to 10 ft seas is arriving along 03.4S and will continue to propagate N reaching the Pacific coast of Panama early next week before beginning to subside. REMAINDER OF THE AREA... The 1010 mb remnant low of former tropical cyclone Kenneth is located near 29N135W. No associated convection is present. Recent scatterometer data and a nearby buoy indicate fresh to near gale force winds and 8 to 12 ft seas in the NW semicircle of the low. Winds are forecast to diminish to 20 kt or less by this afternoon, with associated seas then subsiding to less than 8 ft late tonight into early Sun. Otherwise, the subtropical ridge extends from 32N130W to 18N118W and is accompanied by moderate anticyclonic winds and 4 to 6 ft seas. Fresh to locally strong southerly winds currently S of the monsoon trough from roughly 05N to 10N between 98W and 118W support 8 to 9 ft seas in cross-equatorial southerly swell. This area of winds and seas is forecast to expand out to the tropical waters from 05N to 13N between 98W and 121W by early Sun, then from 05N to 16N between 87W and 122W by early Monday. $$ Lewitsky