Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1156 AM EDT Thu Jul 05 2018 Valid 12Z Sun Jul 08 2018 - 12Z Thu Jul 12 2018 ...Weather threats/highlights and Guidance evaluation/preferences... It remains the case that an upper high will dominate much of the lower 48 next week. Troughs over the Northwest and Northeast overall flatten with time as a more zonal flow takes shape along the US/Canadian border. Heights will become above average coast to coast which supports near to above average temperatures over most areas outside the southern tier. A moderating front in the east will dissipate next week as western North American fronts shift downstream across the northern plains, Upper Midwest/Great Lakes and Northeast along with thunderstorm focus and local severe storm threat as per SPC. The Southwest will see enhanced monsoonal moisture around the upper high realized as precipitation initially over the higher terrain and then into some of the lower deserts. The WPC medium range product suite was mainly derived from a blend of reasonably clustered guidance from the 00 UTC GFS/ECMWF and NAEFS/ECMWF ensembles into Day 5/Tue. Quickly switched to ensembles only later Tuesday to days 6/7 given increasing model forecast spread/smaller scale system uncertainty. The 06 UTC GFS/GEFS trended toward progression, but this scenario seems less likely considering upstream northern Pacific to Alaskan flow amplification. Schichtel WPC medium range 500 mb heights, surface systems, weather grids, quantitative precipitation, winter weather outlook probabilities and heat indexes are found at: http://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif http://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif http://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html http://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml http://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 http://www.wpc.ncep.noaa.gov/heat_index.shtml