Extended Forecast Discussion NWS Weather Prediction Center College Park MD 101 AM EDT Mon Jul 23 2018 Valid 12Z Thu Jul 26 2018 - 12Z Mon Jul 30 2018 ...Southwest/West heat wave lingers into late week... ...Heavy rainfall threat shifts to the Central Rockies/Plains then Mid-MS Valley/Mid-South... ...Guidance/Uncertainty Assessment and Weather Threats... Amplified mid-upper level troughing/height falls work over the Great Lakes/Midwest and Northeast later week into this weekend. Expect some periods of heavy convective rainfall with local runoff issues with passage of lead moisture pooling frontal systems. Additional activity will trail southward along/off the east coast to FL. Deepened moisture mmay allow some record high minimum temperatures over New England. Meanwhile, a hot mid-upper level ridge over the Southwest and spread up over the West and potential for record maximum temperatures will ease later this week, but monsoonal moisture could allow for more record high minimum temperatures. A series of impulses rotating within and on the periphery of the ridge dig southeastward into the central states to interact with surface boundaries/instability and favorable lower level moisture inflow/convergence. Forecast spread increases with potential stream interactions/wave genesis with mid-upper level trough redevelopment from the n-central U.S. through the MS Valley days 6/7. Recent GFS runs have trended toward a bit less amplified/more progressive solution with this feature. The SW/Wrn U.S. ridge position, recent ern U.S. system history, continuity and a majority GEFS/ECMWF ensembles show better support for a solution more in line with a more amplified ECMWF. Overall, this pattern supports multiple episodes of heavy convection from the central Rockies/Plains to the Mid-MS Valley and Mid-South. Convective complexes/repeat cells will lead to locally excessive rainfall threats. Overall, the WPC medium range forecast suite was derived from reasonably well clustered guidance from the GFS/ECMWF/UKMET Thu-Sat. Opted to blend the well clustered ECMWF and GEFS/ECMWF ensemble means days 6/7. 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