000 AXPZ20 KNHC 270230 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Sun Aug 27 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 0000 UTC surface analysis and satellite imagery through 0230 UTC. ..TROPICAL WAVES AND TROPICAL LOWS... A surface trough, or a low latitude tropical wave, is analyzed from 01N79.5W to 10N79W and is accompanied by scattered moderate isolated strong convection N of 05N and E of the wave to well inland Colombia. This convection will move W offshore Colombia for the next several hours. A tropical wave is analyzed to the N of 11N along 96.5W is moving W at about 12 kt. Scattered moderate isolated strong convection is observed over waters within 150 nm W of the wave axis. A tropical wave is analyzed from 10N114W to 21N111W and has been moving W at 10 kt over the past 24 hours. Scattered moderate isolated strong convection is noted within 150 nm W of the wave axis. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends W across the far SW Caribbean along 09.5N and continues W to the Pacific Coast of Costa Rica at 10N84W, then turns NW to 13N95W and through a tropical wave at 13N97W to 15N106W, then turns SW through another tropical wave at 13N113W to beyond 12N140W. Scattered moderate isolated strong convection is observed within 150 nm either side of a line from 07N98W to 13N107W, and elsewhere within 150 nm either side of a line from 12N116W to 09.5N140W. ...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 Sun, 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 well beyond 250 nm. The resultant pressure gradient will support a gentle NW breeze across the open waters W of the Baja California Peninsula on Sun, then increasing to a moderate NW breeze on Sun evening within about 90 nm of the Pacific Coast of Baja California. Expect 3 to 6 ft seas. 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 late Mon night through midday on Tue. Expect only a light SW-W-NW wind shift along the front. Gulf of California...light to gentle southerly flow will become light and variable flow on Sun night, with little change then expected through Wed evening. The pressure gradient will begin to tighten late Wed in response to a tropical low developing well S of the southern tip of the Baja Peninsula. May see fresh SE winds, and 6 to 8 ft seas spreading N across the southern Gulf of California on Fri morning. Gulf of Tehuantepec: light northerly nocturnal drainage winds are forecast this week, with light to gentle onshore flow during the day. Fresh to locally strong southwesterly monsoon flow and long period cross-equatorial swell, in the form 7 to 10 ft seas, will arrive across the waters 250 nm seaward between 100W and 110W on Sun as a 1008 mb surface low develops along the northward shifting monsoon trough near 15N112W on Sun night. A weaker surface low should develop near 15N100W on Mon, and move NW paralleling the Mexican coast through Mon night, eventually losing identity in the cyclonic circulation associated with the stronger low further W that will move N along 111W through Wed, then turn WNW along about 21N late in the week. A band of fresh to locally strong southerly flow is forecast to develop within about 300 nm E of the low, and these conditions will shift N and W across the Mexican offshore waters between about 105W and 115W through Fri. Extended guidance hints at favorable conditions for this low to deepen, with at least near gale force cyclonic winds late in the week as the low continues NW across the open waters W of the Baja Peninsula. Plenty of uncertainty in this scenario, and changes to track and intensity are very likely. 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 is currently along 03.4S, and will continue to propagate N reaching along 06N by early Mon, then subside through Tue. REMAINDER OF THE AREA... The remnant low of former tropical cyclone Kenneth continues to spin near 29N135W. The estimated minimum central pressure is 1012 mb. A recent scatterometer pass detected a band of strong NE-E winds between 45 nm and 90 nm over the N semicircle, with 6 to 8 ft seas. Expect the associated winds to diminish to 20 kt or less, and seas to subside to less than 8 ft in about 12 hours. A ridge extends from 32N129W to near 20N111W, and is accompanied by moderate anticyclonic winds and 4 to 5 ft seas. Fresh to locally strong southerly monsoonal winds and seas of 7 to 10 ft are observed from 04N to 11N between 97W and 123W. These conditions will shift N through Sun with a surface low previously described developing near 15N112W. Expect fresh SW flow from 10N to 17N between 105W and 115W through most of the upcoming week as the low shifts N into the offshore zones covered above. $$ Nelson