Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1159 PM EDT Wed Jul 31 2019 Valid 12Z Sun Aug 04 2019 - 12Z Thu Aug 08 2019 ...Overview and Guidance/Predictability Assessment... Strong upper ridging over the Gulf of Alaska and the northeast Pacific favors troughing along the Pacific Northwest and downstream through the Great Lakes with weakening ridging over the Four Corners region. The model/ensembles mostly agree on the longwave pattern and a blend of the deterministic models sufficed for the first couple of days of the period Sun-Mon. The ECMWF was still quicker/east of the consensus over Washington to move the upper low (or part of it) eastward while the GFS and most ensembles were slower (the preferred position). Thereafter, models/ensembles showed typical spread for a day 5-7 forecast and a blend of the GFS/ECMWF and increasingly their ensemble means served well to minimize change to the forecast given the relatively stable ensemble means. ...Weather Highlights/Threats... Monsoonal moisture will focus rainfall over the Four Corners next week as the upper high weakens. Coverage is expected to slowly decrease Sun-Tue but the ensembles hint at a resurgence from western Mexico by next Wed-Thu which may creep into Arizona. Elsewhere, rainfall will follow the front in the north but be more scattered and diurnally-favored in the afternoon in the Southeast. Temperatures will be a bit cooler than average over the central states and later over parts of the West as troughing pushes inland. Milder than average temperatures are expected over the Great Lakes and Northeast ahead of the northern tier system. Elsewhere, temperatures will be within a few degrees of typical early August values during the day and near/above average for overnight mins in much of the West Sun-Tue then into the Rockies Wed-Thu. Fracasso 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