Extended Forecast Discussion NWS Weather Prediction Center College Park MD 251 AM EDT Mon Jul 26 2021 Valid 12Z Thu Jul 29 2021 - 12Z Mon Aug 02 2021 ...Overview with Weather Highlights/Hazards... Guidance has been increasingly consistent over the last few days and overall agrees to gradually weaken and shift a closed upper high southward over the central U.S. late week into next, with ridging spreading back across the Rockies to the north-central Intermountain West. As impulses and moisture lift across the West between the ridge/closed high and emerging eastern Pacific troughing, expect widespread chances for monsoonal rainfall with isolated local runoff issues will spread from the Southwest/California to across the Great Basin and Rockies where some record warm minimum temperature records may be observed. Meanwhile, multiple shortwaves will dig downstream from the ridge to amplify a mean upper trough over the Midwest/Northeast. Strong convection and locally heavy downpours may periodically focus with moisture/instability pooling near wavy and slow moving fronts under favorable upper support. Wavy frontal progression, convective outflow and reinforcing frontal surges are expected to shift best focused rainfall chances later this week from the Midwest to Northeast down to the Southeast. Dependent on frontal boundary placement/reinforcement and smaller scale surface lows upstream, focused moisture will meanwhile also round the top of the central U.S. ridge to fuel periods of renewed convection/local downpours from the northern Plains to the Midwest/Tennessee Valley. ...Guidance/Predictability Evaluation... The medium range pattern evolution at mid-larger scales offers above average predictability Days 3-7. An overall trend in guidance over the last few days to develop an unseasonably amplified eastern U.S. upper trough over time remains reasonable considering the initial strength of the upstream ridge. The WPC medium range product suite was primarily derived from a composite blend of well clustered guidance of the 18 UTC GFS and 12 UTC ECMWF/UKMET/Canadian along with the 01 UTC National Blend of Models Thursday into Saturday before switching to a still compatible composite blend of the ECENS/GEFS ensemble means and GFS/ECMWF heading into early next week. Latest 00 UTC guidance generally remains in line with our earlier guidance and blend. WPC product continuity was well maintained in this plan. Schichtel Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook 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