Extended Forecast Discussion NWS Weather Prediction Center College Park MD 257 AM EDT Sat Jul 30 2022 Valid 12Z Tue Aug 2 2022 - 12Z Sat Aug 6 2022 ***Heat wave expected from the Northern Plains to the Northeast next week*** ...General Overview... A welcomed pattern change is forecast for the northwestern U.S. early next week as an upper level trough and associated cold front herald a return to much more pleasant temperatures. The ridge axis and the accompanying heat wave will progress from the central/northern Plains to the Great Lakes/Northeast by Thursday. By the end of the week, a second trough is likely across the Pacific Northwest and Northern Rockies, with a downstream ridge encompassing much of the central and eastern U.S. with widespread hot and humid weather expected. ...Guidance Evaluation/Predictability Assessment... The 00Z model guidance suite is initially in good overall synoptic scale agreement across the continental U.S. on Tuesday, and the models are a little more in line across the Pacific Northwest compared to similar time scales yesterday. The models have also come in better focus on a second and reinforcing trough arriving from western Canada by Thursday/Friday across the Northwest, with the GFS more progressive with that feature as it tracks across the northern tier states. The WPC forecast was derived from a CMC/GFS/ECMWF blend as a starting point through Wednesday, and then gradually increased percentages of the ECENS and GEFS means while still maintaining some GFS/ECMWF and slightly less CMC. ...Weather/Hazards Highlights... Another heat wave is expected to make weather headlines on Tuesday across the Northern Plains and Upper Midwest for Tuesday and Wednesday, with highs running on the order of 15-20 degrees above average, potentially setting some daily records. The heat then reaches the Great Lakes, Ohio Valley, and then the East Coast for later in the week as the month of August begins hot and humid. Heat indices may exceed 105 degrees for some areas. Meanwhile, temperatures will likely be near to slightly below normal across much of the western U.S., with the coolest readings over Washington and Oregon. In terms of precipitation, there will likely be some abatement in the coverage of heavy rainfall across much of the nation with no Slight Risk areas of excessive rainfall for Tuesday and Wednesday. There will still be plenty of monsoonal moisture in place across the southwestern U.S., but not to the extent that has been observed recently. However, this may increase again going into Friday and next Saturday with a greater coverage of showers and storms. There may also be a round of heavy showers and strong thunderstorms across portions of the Great Lakes and the Northeast ahead of a cold front towards the end of the week. Hamrick Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation, experimental excessive rainfall outlook, 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/#page=ero https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml