Extended Forecast Discussion NWS Weather Prediction Center College Park MD 146 AM EDT Wed Jul 25 2018 Valid 12Z Sat Jul 28 2018 - 12Z Wed Aug 01 2018 ...Heat wave lingers over the West... ...Heavy rainfall threat to spread from the Central Plains to Mid-South then the Southeast/East... ...Guidance/Uncertainty Assessment and Weather Threats... Weekend mid-upper level troughing lifts over the Northeast with scattered convection, but heavy activity trails southward off the east coast into Florida. Meanwhile, a Southwest/West mid-upper level ridge offers more above normal summer heat into next week. Active impulses linger in Southwest/srn Rockies monsoonal flow and overtop the ridge. These dig into the central U.S. in favorable upper diffluence to interact with surface boundaries, instability, and favorable low level moisture inflow/convergence. Weekend mid-upper level trough amplification over the n-central U.S. will dig through the MS Valley early next week and induce frontal lows and gradual system progressions downstream over the E-Central U.S. Expect multiple episodes of heavy convection from the central Rockies/Plains through the mid-lower MS/Mid-South this weekend whose threat spreads over the E-Central to Southeast/ern U.S. early-mid next week. Heavy rainfall with repeat cells offer a widespread excessive rainfall threat fueled by an increasingly deep layered moisture inflow pattern to align roughly parallel to the main front as storms channel between the slow to translate upstream trough aloft and a downstream western Atlantic ridge. The WPC medium range product suite was mainly derived from a composite blend of best clustered guidance from the 12 UTC ECMWF and 12 UTC GEFS/NAEFS/ECMWF ensembles in a pattern with above normal predictability. Schichtel WPC medium range 500 mb heights, surface systems, weather grids, quantitative precipitation, winter weather outlook probabilities and heat indexes are found 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