000 AXPZ20 KNHC 190257 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Fri Aug 19 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... Topical Depression Twelve-E is centered near 17.8N 110.4W at 19/0300 UTC or about 308 nm south of the southern tip of Baja California moving northwest at 6 kt. Estimated minimum central pressure is 1005 mb. Maximum sustained winds are 30 kt with gusts to 40 kt. Latest satellite imagery shows a large burst of numerous strong convection within 90 nm of the center in the south and southwest quadrants. Scattered moderate to isolated strong convection is within 120 nm of the center in the northwest quadrant, and also within 30 nm of 16N109W. The last satellite visible imagery showed low cloud lines rotating cyclonically into the deep convective activity from the northeast and southeast quadrants of the depression as it remains under upper level northeast shear. The depression is forecast to intensify to a minimal tropical storm near 18.6N 111.0W by early Friday morning. It is then forecast to only increase slightly in intensity as it nears 19.4N 111.5W early Friday evening before gradually weakening back to a depression by Saturday evening as it encounters a less favorable atmospheric environment. Please see the latest NHC Public Advisory under AWIPS/WMO headers MIATCPEP2/WTPZ32 KNHC and the Forecast/Advisory under the AWIPS/WMO headers MIATCMEP2/WTPZ22 KNHC for more details. ...TROPICAL WAVES... A tropical wave axis is along 98W north of 09N to inland southeastern Mexico moving west at 10 to 15 kt. Scattered moderate isolated strong convection is within 60 nm east of its axis from 12N to 13N. Scattered moderate convection has just developed within 60 nm w of its axis from 11N to 12N. Isolated weak showers and thunderstorms are elsewhere within 120 nm of the axis. A tropical wave axis is along 138W from 12N to 19N moving west at 5 to 10 kt. Scattered moderate isolated strong convection has recently developed within 30 nm of 12N138W. The pressure gradient between the wave and surface ridging to the north is still tight enough to support fresh trades on the northwest side, allowing for an area of combined seas to 8 ft to linger. These seas will subside as the wave reaches 140W by 24 hours. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N84W to 08N92W to 10N102W. It resumes from 16N112W to 13N121W to low pressure near 09N129W 1011 mb, and to 13N135W to beyond 10N140W. Scattered moderate to strong convection is within 120 nm north of the axis between 112W and 120W. Scattered moderate convection is within 60 nm south of the axis between 84W and 86W, and within 60 nm south of the axis between 120W and 121W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface ridge extends across the area north of 20N between 110W and 120W. Scatterometer data from Thursday afternoon indicated gentle to moderate northerly flow around this ridge north of 20N, with combined seas of 4 to 7 ft. Meanwhile light to moderate southerly flow prevails in the Gulf of California with a north to south trough located along the eastern shore of the Baja California peninsula. Little change in these conditions is anticipated through the next several days, except winds may pulse to moderate to fresh just offshore of the western coast of the Baja California peninsula late this weekend into early next week as the pressure gradient tightens slightly. To the south of 20N, the main feature of interest is recently formed Tropical Depression Twelve-E. Please refer to the special features section above for details on this system. Otherwise, fresh to strong offshore winds in the Gulf of Tehuantepec will diminish in the next few hours, with moderate to fresh offshore flow anticipated during the overnight hours through early next week. Scattered moderate isolated strong convection has moved to within 90 nm offshore the coast of Mexico between Cabo Corrientes and Manzanillo. Similar activity is just along and inland the coast of Mexico between Puerto Angel and Acapulco. This activity is being steered by upper level strong northeast winds located to the southeast of a large anticyclone centered over west-central Mexico. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to locally fresh northeast to east offshore winds are expected again in and just downstream of the Gulf of Papagayo tonight into early Friday morning. Otherwise, light to moderate winds will prevail on either side of the monsoon trough through early next week with combined seas of 4 to 7 ft. REMAINDER OF THE AREA... A surface ridge associated with a strong 1036 mb high located well north of the area near 44N142W extends a ridge southeast through 32N136W and to near 23N121W. Moderate to locally fresh trades and combined seas of 4 to 7 ft dominate the remainder of the basin. The ridging is forecast to break down as a decaying cold front or remnant trough drops into the northern portion this weekend, stalling and lingering over the northwest portion through early next week. This will allow for trades to diminish to mainly light to moderate as the pressure gradient weakens. $$ Aguirre