Extended Forecast Discussion NWS Weather Prediction Center College Park MD 152 AM EDT Mon Aug 12 2019 Valid 12Z Thu Aug 15 2019 - 12Z Mon Aug 19 2019 ...Overview and Guidance/Predictability Assessment... Upper troughing digs through the Northwest Thu/Fri as ridging settles over the Southwest and south-central U.S. This favors downstream troughing into the East. Northwest U.S. trough energy is expected to eject over the northern Rockies/Plains then Midwest/Great Lakes Sat-Mon, but details remain uncertain as models remain quite run-run inconsistent. Accordingly, The WPC medium range product suite was mainly derived from a blend of the more capatable 18 UTC GEFS mean, 12 UTC ECMWF ensemble mean, and National Blend of Models. ...Weather Highlights/Threats... A wavy lead frontal system will shift southward through the eastern and central states, stalling out over the South/Southeast later week. Widespread showers and thunderstorms including a threat of local cell training/runoff issues are expected to settle southward from the Mid-Atlantic to focus into the Southeast/Gulf Coast as deepened Gulf moisture streams into the vicinity of the front. There remains a threat of excessive heat with some record pre-frontal high minimum temperatures for portions of Texas and Florida. The Southwest will also experience hot temperatures through the period under the upper high/ridge, mitigated locally by monsoonal convection. Overtop, upper trough amplification over Northwest/West and potentially robust system/height fall ejections over Rockies to the north-central U.S. by next weekend would provide dynamics and instabilities supportive of periods of enhanced thunderstorms/convective clusters with a threat of heavy rainfalls. Tate/Schichtel Additional 3-7 Day Hazards information can be found on the WPC medium range hazards chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation, winter weather outlook probabilities and heat indices are at: https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml