Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1229 AM EDT Fri Aug 03 2018 Valid 12Z Mon Aug 06 2018 - 12Z Fri Aug 10 2018 ...Overview and Guidance/Uncertainty Assessment... Pattern next week will feature a strong upper high over the Southwest and resurgent troughing in the eastern half of the lower 48. An upper low well off the Pacific Northwest coast will only slowly move toward British Columbia by the end of next week. The models/ensembles were in good agreement overall with some expected timing/amplitude differences. The uncertainty mostly stemmed from Alaska in a swift zonal flow. Though the 12Z ECMWF was slower than the GFS/UKMET/Canadian in the high latitudes, the lingering uncertainty with the upper low placement well west of Washington coupled with uncertain initial conditions over the north Pacific suggests that a blended solution should suffice. The deterministic models have led the way for the ensembles over the past few runs and opted to weight them in the majority through the period. ...Weather Highlights/Threats... With the upper low lingering offshore, ridging will support well above average temperatures in the west and especially the interior west. Record highs (including warm overnight minimums) are again likely for some areas west of the Divide. The east will see one day of well above average temperatures on Monday (some record highs possible around NYC) before heights lower for the rest of the week and the front pushes eastward, raising the chance for precipitation. Precipitation will focus along/ahead of the front that will push out of the High Plains/Great Lakes early in the week and then into the Southeast from Wed-Fri. Warm/humid airmass will support scattered convection with 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