000 AXPZ20 KNHC 252140 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Fri Aug 25 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 2130 UTC. ...SPECIAL FEATURE... Gale Warning...The remnant low of former tropical cyclone Kenneth continues to spin near 29N135W with scattered moderate convection currently observed within 90 nm over the NW quadrant. The estimated minimum central pressure is 1012 mb. The pressure gradient between the low and a subtropical ridge to the NE supports 30 to 35 kt gale force winds within 120 nm over the N semicircle of the center, with combined seas of 11 to 14 ft. A large area of strong to near gale winds surround the gale area within 240 nm over the NW and 90 nm over the SE semicircles. The gale center is forecast to move W to near 29N136W tonight and weaken to a near gale 30 kt system. Thereafter, the low will meander and slowly weaken with winds 20 kt or less and seas less than 8 ft on Sat. The low should weaken to an open trough on Sun night. Please refer to the High Seas Forecast issued under WMO/AWIPS headers FZPN03 KNHC/MIAHSFEP2 for more information. ..TROPICAL WAVES AND TROPICAL LOWS... A tropical wave is analyzed to the N of 09N along 90W is drifting slowly W. Scattered moderate isolated strong convection is noted within 120 nm of the wave axis. Model guidance is hinting at a surface low developing along this wave near 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 tropical wave is analyzed from 11N108W to 19N104W and has been moving W at 8 kt over the past 24 hours. Scattered moderate isolated strong convection is noted within 240 nm of the wave axis. This wave will likely lose identity over the next day or so. A 1011 mb surface low is embedded in the monsoon trough at 12N138W with scattered moderate isolated strong convection observed within 180 nm over the NW quadrant of the low. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends W across the far SW Caribbean between 09N and 10N and off the Pacific Coast of Costa Rica at 10N85W to a tropical wave at 11N90W, then dips SW to 09.5N96W, then turns WNW to 12N122W and through an embedded surface low at 12N138W. Scattered moderate isolated strong convection is observed elsewhere within 210 nm either side of lines from 07N86W to 10N104W and from 11N115W to 12N131W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A NW to SE orientated low level trough will meander E to W across the Baja California Peninsula and Gulf of California through the upcoming weekend with a weak surface low developing intermittently along the trough over the far northern Gulf of California waters. A NW to SE orientated ridge extends across EPAC waters beyond 250 nm. The resultant pressure gradient will support a moderate NW breeze across the open waters W of the Baja California Peninsula through Sun evening, except becoming a fresh NW breeze 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. Gulf of California...light to gentle southerly flow will persist across the Gulf of California this weekend, except a brief moderate southerly breeze will develop intermittently just S of the low pres over the Gulf waters, roughly along 30N. A gentle to brief moderate NW breeze will follow the cold front on Mon evening. Gulf of Tehuantepec: light to gentle N drainage winds are forecast through the weekend during the overnight hours, with gentle onshore flow during the day. Strong southwesterly monsoon flow and long period cross- equatorial swell, in the form 7 to 9 ft seas, will arrive across the waters between 97W and 106W at about 250 nm seaward on Sun. By then a surface low is forecast to develop along the northern extension of a tropical wave near 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, with at least near gale force cyclonic winds late in the week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Moderate nocturnal drainage forecast on Sun night. 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 9 ft seas will arrive at 03.4S on Sat and continue to propagate N reaching the Pacific coast of Panama early next week before beginning to subside. REMAINDER OF THE AREA... Except as discussed in the special features paragraph, the subtropical ridge extends from 32N129W to near 22N134W, and is accompanied by moderate anticyclonic winds and 4 to 5 ft seas. Moderate to locally fresh southerly winds currently S of the monsoon trough are forecast to increase to a strong breeze from 05N to 11N between 97W and 119W by early Sat, and expand out across the tropical waters from 06N to 14N between 100W and 122W on Sun, with seas building to 10 ft in southerly swell. $$ Nelson