000 AXPZ20 KNHC 262145 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ..TROPICAL WAVES AND TROPICAL LOWS... A tropical wave is analyzed to the N of 11N along 95.5W is moving W at about 12 kt. Scattered moderate isolated strong convection is observed over waters within 120 nm of the wave axis. A tropical wave is analyzed from 10N112W to 20.5N110W and has been moving W at 8 kt over the past 24 hours. Scattered moderate isolated strong convection is noted within 120 nm W of the wave axis. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends W across the far SW Caribbean between 08.5N and 10N and continues W to the Pacific Coast of Costa Rica at 09.5N84.5W. The monsoon trough then turns NW through a tropical wave at 14N96W, then turns SW to 13N102W, then turns NW again through another tropical wave at 14N111W, then SW again and then meanders W along 11.5N to beyond 140W. Scattered moderate isolated strong convection is observed within 90 of 05N79W, and within 120 nm either side of a line from 13.5N98W to 10N105W, and elsewhere within 180 nm either side of a line from 09N110W to 11.5N119W to 09N140W. Scattered moderate isolated strong convection is noted to N of the monsoon trough within 45 nm either side of a line from 16N103W to 19N108W. ...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 well beyond 250 nm. The resultant pressure gradient will support a gentle NW breeze across the open waters W of the Baja California Peninsula through Sun night, except becoming a moderate 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 through midday on Tue. Expect only a gentle 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 shifting 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 9 ft seas, will arrive across the waters 250 nm seaward between 100W and 110W on Sun. The array of model guidance leads to solution of a couple of surface lows developing along the northward shifting monsoon trough as early as Sun night. A weak low should develop near 15N100W and move NW paralleling the Mexican coast on Mon and Mon night, eventually losing identity in the cyclonic circulation associated with a second, stronger low that will develop in the vicinity of 15N111W on Mon, and move N 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. Associated winds have diminished to 20 kt or less, and seas of 6 to 8 ft currently within 180 nm over the NW quadrant are forecast to subside to less than 8 ft tonight. 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 15N111W. 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