Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1152 AM EDT Sat Aug 04 2018 Valid 12Z Tue Aug 07 2018 - 12Z Sat Aug 11 2018 ...More Hot Temperatures for the West... ...Pattern Overview and Guidance/Predictability Assessment... An upper high in the west may begrudgingly abate next weekend as ern Pacific upper trough energy lifts into British Columbia. Downstream, the e-central U.S. will experience another upper trough amplify and settle into the region. Model and ensemble mass field and precipitation forecast clustering is better than normal, bolstering forecast confidence. A composite blend of the 06 UTC GFS/GEFS mean and 00 UTC ECMWF/ECMWF ensemble mean seems to provide a good basis for these forecasts into Day5/Thu. Guidance spread becomes more of an issue Thu-next Sat with the ECMWF more amplified than recent GFS runs. Recent flow history and ensembles, especially the ECMWF ensembles, seem to best support pattern evolution on the amplified side of the full envelope of solutions, but not as amplified as the latest ECMWF that itself has trended quite a bit more amplified/less progressive than recent prior versions. ...Weather Highlights and Hazards... With the upper low lingering offshore for most of the period, ridging will support well above average temperatures in the West/interior West. Some record highs and numerous record warm minimums are again likely for the Desert Southwest, Great Basin, and interior Northwest until heights fall and the front pushes ashore in about a week. Precipitation should be confined to coastal/northern Washington and then mainly on the upper diffuent east side of the upper high over NM/CO eastward to the southern Plains. The mean upper trough settling over the e-central to srn/ern U.S. meanwhile raises the chance for periods of heavy convective precipitation that will focus along/ahead of a wavy surface front and with warm sector meso-boundaries. Activity will be maximized as a series of less predictable embedded shortwave impulses interact with pooled deepened moisture and instability. As the front settles into the South late next week, the typical warm/humid airmass will support additional convection/locally heavy rainfall. 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