Extended Forecast Discussion NWS Weather Prediction Center College Park MD 256 AM EDT Sat Jul 04 2020 Valid 12Z Tue Jul 07 2020 - 12Z Sat Jul 11 2020 ...Guidance/Predictability Assessment... Forecast spread increases through medium range time scales a bit more than average for this time of year. Accordingly, the WPC medium range product suite was primarily derived from a blend of the reasonably compatible 12 UTC Canadian, 18 UTC GEFS mean, 12 UTC ECMWF ensemble mean and the 01 UTC National Blend of Models. Leaned blend weighting toward the GEFS mean and especially the ECMWF ensemble mean to address growing forecast spread and to maintain good WPC continuity. The 12 UTC Canadian was best clustered with the ensemble means near or slightly less progressive than a forecast envelope composite and was included in the blend to provide added detail consistent with uncertainty. In the East, recent ECMWF system emphasis including the newest 00 UTC run are on the progressive side. with GFS/UKMET emphasis on the slower side. Out West, recent GFS runs including the latest 00 UTC GFS remain faster bringing a main upper trough to the Northwest Thursday compared to other guidance, then amplify the flow more in earnest downstream heading into next weekend. ...Weather Pattern/Hazard Highlights... Unsettling Pacific upper trough energies will eventually work inland over the Northwest next week. A steady diet of ejecting impulses will progress downstream over southern Canada and the U.S. northern tier. This will force a series of moderating fronts across the region and spawn periods with strong instability/convection and locally heavy downpours/runoff issues. Potential may focus from the northern Rockies/Plains to the Upper Midwest. Lead flow and mean upper ridging may bring the most anomalous heat over the Midwest/Northeast. Elsewhere, triple digit maximum daytime temperatures will focus from the Desert Southwest/southern Great Basin to the south-central Plains and hot and humid weather (including some record warm overnight temperatures) will rule a broad expanse south of these fronts over much of the central and eastern U.S. Some heavy convective downpours/local runoff issues may focus into the South/Southeast near a slow moving upper trough/closed low and wavy front. Potential development of a slowly northward lifting coastal low may provide an additional heavy rainfall mechanism later next week into the Mid-Atlantic. 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