Extended Forecast Discussion NWS Weather Prediction Center College Park MD 134 AM EDT Sat Aug 10 2019 Valid 12Z Tue Aug 13 2019 - 12Z Sat Aug 17 2019 ...Overview and Guidance/Predictability Assessment... It is still expected that generally quasi-zonal flow will prevail early next week over the CONUS, with embedded shortwaves tracking through and some indication of troughing along the West Coast. By midweek, more amplified flow begins rebuilding as a deeper trough digs into the Northwest and ridging centered in the Southern Plains strengthens by Thu/Fri. This would likely lead to troughing downstream in the eastern U.S. Deterministic guidance continues to offer significant timing differences with embedded systems within the flow, but the 12 UTC GEFS/ECMWF ensemble means remain in pretty good alignment, so this multi-model blend was used days 3-7 along with the National Blend of Models. WPC product suite continuity was well maintained with this solution despite marginal system predictability. ...Weather Highlights/Threats... Widespread rain and thunderstorms are expected around an early to midweek Great Lakes/Ohio Valley to Northeast low pressure system ahead of a main trackable shortwave. Gulf moisture flowing into the vicinity of the associated front that pushes to the South and especially the Southeast will lead to scattered showers and thunderstorms including potential for some cell training and related runoff issues. Upstream, impulse and upper jet energies working out form the unsettling western U.S. upper trough later next week will also support some organized convective developments out into the north-central U.S. Temperature-wise, pre-frontal above average temperatures are forecast in the southern tier underneath the upper high that will lead to the likelihood of excessive heat and widespread record high minimum temperatures. Meanwhile the northwestern and north-central to Northeast CONUS will generally have below average temperatures. 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