000 AXPZ20 KNHC 182159 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Thu Aug 18 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...SPECIAL FEATURES... Newly formed Tropical Depression Twelve-E is centered near 17.8N 110.1W at 18/2100 UTC or about 304 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 deep convection over the earlier partially exposed center. This convection consist of strong intensity within 180 nm of the center in the southwest quadrant, and within 90 nm of the center in the northwest quadrant. Low cloud lines are observed rotating cyclonically into the deep convective activity. The depression is forecast to intensify to minimal tropical storm near 18.5N 110.7W late tonight. It is forecast to maintain minimal tropical storm strengthen as it reaches near 19.4N 111.3W early Friday afternoon and into Friday evening before weakening back to a depression on Saturday as it encounters a stable 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/WTPZ32 KNHC for more details. ...TROPICAL WAVES... A tropical wave axis is along 95W north of 10N to inland southeastern Mexico moving west at 10 to 15 kt. Scattered moderate convection is within 30 nm of 13N96W. Isolated weak showers and thunderstorms are elsewhere within 120 nm of the axis. A tropical wave axis is along 136W from 11.5N to 20N moving west at 5 to 10 kt. Weak low pressure that was along the wave axis has dissipated during the past several hours, as has any associated deep convection. Even so, the pressure gradient between this feature 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 feature reaches 140W by 24-30 hours. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N84W to 08N91W to 10N100W. It resumes from 16N112W to 13N120W to low pressure near 09N129W, and to 13N135w to beyond 10N140W. Scattered moderate to isolated strong convection is within 60 nm south of the axis between 112W and 116W. Scattered moderate convection is within 150 nm south of the axis east of 88W, within 120 nm north of the axis between 88W and 94W, and within 60 nm north of the axis between 120W and 122W. Scattered moderate convection is seen from 11N to 16N between 100W and 107W. Additional scattered moderate is roughly within 90 nm of the coast of Mexico between 98W and 104w. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface ridge extends across the area north of 20N between 110W and 120W. The latest scatterometer observations indicate 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 newly 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. 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 through, 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