Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1200 PM 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 00 UTC ECMWF and 00 UTC NAEFS/ECENS ensemble means. Increased blend weighting toward the ensemble means through time to address growing forecast spread and to maintain good WPC continuity. The GFS was a bit of an outlier across the eastern U.S., bringing the upper-level low initially across the lower Mississippi Valley much farther north through late next week relative to the consensus of other guidance. This results in a much wetter scenario across the Ohio Valley and east to the Mid-Atlantic in the GFS, a scenario which is not preferred at this time. Farther west, the GFS remained faster than consensus with bringing a relatively amplified shortwave into the Pacific Northwest late next week, while the ECMWF was more in line with the ensemble means, at least in terms of timing. One aspect for which models/ensemble show good consensus, is on the development and intensification of an upper-level ridge centered across the Southern Rockies/High Plains by late next week, supporting a trend toward troughing/cyclonic flow across the eastern third of the CONUS. ...Weather Pattern/Hazard Highlights... Unsettling Pacific upper trough energies will eventually work inland over the Northwest next week. A steady stream 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 across coastal portions of the Southeast and possibly the southern Mid-Atlantic. Ryan/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