Extended Forecast Discussion NWS Weather Prediction Center College Park MD 227 AM EDT Sun Aug 05 2018 Valid 12Z Wed Aug 08 2018 - 12Z Sun Aug 12 2018 ...Continued hot for much of the West... ...Pattern Overview and Guidance/Predictability Assessment... An upper low well west of the Pacific Northwest will move into British Columbia and weaken later this week as the upper high over the Southwest attempts to hold in place. Downstream in the east, troughing will settle into the region. A blend of the recent 12Z/18Z models offered a good starting point, but the 12Z ECMWF was notably slower than the consensus with the Pacific upper low and was dropped from the preference by Friday in favor of its ensemble mean. The 12Z Canadian and 12Z/18Z GFS served as some detail to the forecast for next weekend as the system drags a cold front into the interior Northwest. ...Weather Highlights and Hazards... Well above average temperatures are forecast for much of the CONUS west of the Divide except for Montana which will push east. Some record highs and numerous record warm minimums are likely for the Desert Southwest, Great Basin, and interior Northwest until heights fall and the front pushes ashore by the weekend. Precipitation should be confined to coastal/northern Washington and then mainly on the upper diffluent eastern side of the upper high over NM/CO eastward to the southern Plains. Eastern troughing will support periods of heavy convective precipitation that will focus along/ahead of a wavy surface front and co-driven by warm sector meso-boundaries. Shortwaves and weak surface boundaries will briefly increase coverage of rain/storms through the Great Lakes and Northeast. As the front lingers in the South later in the week, the typical warm/humid airmass will support additional convection and locally heavy rainfall. Fracasso 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