Extended Forecast Discussion NWS Weather Prediction Center College Park MD 257 AM EDT Sun Jul 31 2022 Valid 12Z Wed Aug 3 2022 - 12Z Sun Aug 7 2022 ...Heat wave to spread from the Plains to the East Coast next week... ...Wet Monsoonal Pattern continues for the Southwest and Great Basin... ...General Overview... A active upper level flow pattern will be in place across the northern tier states, with a well defined trough and cold front crossing the Great Lakes and then New England by the end of the week. Another trough is expected to reach the Northern Rockies by Friday and then traverse the Northern Plains by next weekend. Meanwhile, the core of the upper ridge intensifies across the central Plains for the end of the week and expands in coverage by the weekend, and the monsoonal pattern across the Four Corners region looks to remain active as well. ...Guidance Evaluation/Predictability Assessment... The 00Z model guidance suite is in very good overall synoptic scale agreement across the continental U.S. on Wednesday, and overall forecast confidence through the end of the week is improved compared to the past two days. The lingering upper low well off the Pacific Coast has been one of the wild cards in the pattern evolution, but there appears to be enough separation between it and the northern stream trough to reduce overall model spread. By next weekend, more substantial differences are apparent across southern Canada and the northern tier states, with the 00Z CMC appearing to be most at odds with the ensemble mean solutions. The WPC forecast was derived from a CMC/GFS/ECMWF/UKMET blend as a starting point for Wednesday, and then gradually increased percentages of the ECENS and GEFS means while still maintaining some GFS/ECMWF and slightly less of the 12Z CMC. ...Weather/Hazards Highlights... Another heat wave is expected to make weather headlines for the second half of the week from the Midwest to the Northeast U.S., with daytime highs running well into the 90s and exceeding 100 degrees in some cases. Meanwhile, temperatures will likely be near to slightly below normal across much of the western U.S. for most of the forecast period. This also includes the Desert Southwest where increased cloud cover and rainfall will keep temperatures in check. In terms of precipitation, there is a stronger model signal for a corridor of heavy showers and storms ahead of the cold front crossing the Great Lakes and Ohio Valley, and a Slight Risk area of excessive rainfall has been added to the Day 4 outlook from northern Illinois to southern Michigan. There will still be plenty of monsoonal moisture in place across the southwestern U.S., with enough expected coverage of slow moving storms to merit a Slight Risk on Day 5 across much of southeastern Arizona. Scattered to numerous showers and storms are also likely for portions of the Gulf Coast region to close out 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