000 AXPZ20 KNHC 261603 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ..TROPICAL WAVES AND TROPICAL LOWS... A tropical wave is along about 94w extending from the Bay of Campeche across SE Mexico and into the tropical eastern Pacific, W at 10 to 15 kt. Scattered moderate to strong convection is noted from 07N to 16.5N between 91W AND 101W. As this wave continues to shift W over the weekend, active convection is expected to continue near it due to broad SW moist monsoonal winds across this region. Model guidance continues to suggest that a surface low will develop along the monsoon trough associated with this wave in the vicinity of 17N106W late Mon. The low is then forecast to move NNW and pass just to the SW of the Baja California Peninsula Wed through Fri. A tropical wave is along 107W-108W S of 20N moving W at around 5 kt. Scattered moderate isolated strong convection is noted from 15N to 20N between 101W AND 111W. Very active convection is seen occurring S of the monsoon trough to the SW of this wave from 08N to 13N between 108W AND 123W. 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 12.5N96W to low pres near 11.5N106W to 13.5N110W to 11N133W to beyond 12N140W. Scattered moderate to strong convection is from 03N to 06.5N between 80.5W and the coast of Colombia. Widely scattered moderate to strong convection is within 120 nm N and 150 nm S of the trough between 123W and 138W. ...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 late afternoon and 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, 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 S swell, producing seas 7 to 10 ft, will develop across the waters S of 18N and W of 96W this afternoon through tonight. A surface low is forecast to develop along a tropical wave in the vicinity of 17N106W by late Mon. The low will lift NNW and produce fresh to strong southerly flow between 110W and the Mexican coast through Thu. Extended model 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 cross-equatorial S swell is producing 5 to 7 ft seas across the offshore waters this morning, and 7 to 9 ft extending further to the equator. This swell will propagate N and reach the Pacific coasts tonight through early next week before beginning to subside. REMAINDER OF THE AREA... The 1010 mb remnant low of former tropical cyclone Kenneth is located near 29N135.5W. No associated convection is present. Recent scatterometer data and a nearby buoy indicate fresh to strong winds and 8 to 11 ft seas in the NW semicircle of the low. Winds are forecast to diminish to 20 kt or less by this evening as the low drifts W and weakens. Otherwise, the subtropical ridge extends from 32N12W to 19N113W 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 strong winds and seas is forecast to expand out to the tropical waters from 09N to 14N between 104W and 116W by early Sun, then from 09N to 14N between 107W and 122W by early Monday. $$ Stripling