000 AXPZ20 KNHC 200255 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Sat Aug 20 2016 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. ...SPECIAL FEATURES... Tropical Storm Kay centered near 19.2N 112.4W at 20/0300 UTC or 300 nm to the south-southwest of the southern tip of Baja California moving northwest at 6 kt. Estimated minimum central pressure is 1000 mb. Maximum sustained wind speed is 40 kt with gusts to 50 kt. Latest satellite imagery shows numerous strong convection within 90 nm of the center in the southwest quadrant. Scattered strong convection is elsewhere within 120 nm west and 60 nm east semicircles of center. Scattered moderate to isolated strong convection is embedded in an outer rainband within 30 nm of 21N112W. Kay is forecast to maintain intensify slightly as it reaches near 19.7N 113.0W early on Saturday, and continue to maintain intensity as it reaches near 20.3N 113.7W early Saturday evening, to near 20.9N 114.6W early on Sunday then begin to weaken as it moves into a more stable environment late Sunday, and as it begins to move across cooler sea surface temperatures. These negative ingredients will cause Kay to gradually weaken to a tropical depression late on Tuesday, and to a remnant low by late Wednesday. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP2/WTPZ22 KNHC for more details. ...TROPICAL WAVES... A tropical wave axis is along 103W/104W from 10N to 17N moving west at 10 to 15 kt. Scattered moderate to isolated strong convection earlier noted ahead of the wave has just about dissipated. The tropical wave may help enhance precipitation along the coast of southwest Mexico through the upcoming weekend as it passes by just to the southwest of the area. A tropical wave, currently over the western Caribbean Sea, is forecast to move across Central America on Sunday, then move into the far eastern part of the area near 91W early on Monday. This wave is expected to be attendant by scattered showers and thunderstorms. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N85W to 09N95W to 09N106W. It resumes to the southwest of Kay at 16N117W to 13N126W to 15N132W to 13N140W. Scattered moderate to isolated strong convection is along the western edge of the first monsoon trough segment from 09N to 11N between 105W and 107W. Scattered moderate convection is from 06N to 09N between 80W and 86W. Similar activity is within 120 nm south of the trough axis between 135W and 138W, and within 30 nm north of the axis between 135W and 138W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Tropical Storm Kay continues to impact portions of the area, and is described in detail in the special features section above. Otherwise, ridging extends into the northern portion ahead of Kay with a northwest to southeast oriented trough along the western Gulf of California. Light to moderate winds prevail outside of Kay under a relatively weak pressure pattern, which will persist into early next week. Combined seas of 4 to 7 ft outside of Kay will gradually subside early next week as Kay weakens. In the Gulf of Tehuantepec, northerly offshore winds will continue to pulse to fresh levels during the late night and early morning hours with nocturnal drainage flow, potentially increasing to fresh to strong by the middle of next week. Scattered moderate convection is observed from 14N to 19N between 104W and 107W. This convection is being driven to the southwest by strong upper level winds over the that portion of the basin. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Offshore winds will pulse to fresh levels in the Gulf of Papagayo and adjacent areas during the overnight and early morning hours through the next several days. Otherwise, light to moderate winds will prevail on either side of the monsoon trough. Combined seas of 4 to 7 ft will gradually subside slightly through early next week as supporting long period south-southwest swells decays. REMAINDER OF THE AREA... A strong 1033 mb high center located well north of the area near 44N144W extends a ridge southeast through 32N140W, and to near 23N117W, with mainly light to moderate trades prevailing. The ridge will break down as a weakening cold front drops down from the north. This decaying boundary will reach from 30N132W to 26N140W by early Saturday where it will stall through the remainder of the day Saturday, before retreating westward as a remnant trough into early next week. This pattern will allow for trades to remain relatively docile. $$ Aguirre