Extended Forecast Discussion NWS Weather Prediction Center College Park MD 350 PM EDT Wed Jul 27 2022 Valid 12Z Sat Jul 30 2022 - 12Z Wed Aug 03 2022 ...Dangerous heat wave persists over the Northwest/Great Basin through the weekend before the anomalous heat shifts east across the north-central U.S. next week... ...Heavy to excessive rain threat for the south-central Plains to the southern Mid-Atlantic Sunday into Monday, with a lingering monsoon in the Southwest through next week... ...Overview... A dangerous heat wave will continue through this weekend across the Northwest before the heat shifts east across the north-central states next week ahead of an upper trough moving into the Pacific Northwest. Upper ridging and heat/humidity will also linger over the southern Plains and lower Mississippi Valley to the south of a wavy quasi-stationary front. This front will remain a focus for multi-day heavy rain threats from the south-central Plains to the southern Mid-Atlantic with excessive rainfall likely Saturday night into Monday. Renewed troughing will take shape across the Great Lakes and Northeast into next week, while a seemingly never ending stream of monsoonal moisture continues to flow into the Southwest and southern Rockies. ...Guidance Evaluation/Predictability Assessment... The latest global deterministic models remain well clustered with the large-scale pattern and evolution of the expansive western/southern U.S. ridge and the trough digging into the Northeast this weekend and its eastward shift early next week. Even differences in the weaker shortwaves moving through the Great Lakes are minor. Out West, there are lingering questions in the timing and strength of a shortwave trough entering the Northwest with the 06Z/12Z GFS more progressive and the 00Z/12Z UKMET just behind in bringing this energy onshore, while the GEFS ensemble means support a slower solution and closer to the 00Z ECMWF/CMC. The result of the more progressive GFS is a flatter pattern over the northern tier and preferences was again given to the ECMWF/CMC later in the blend (along with the GEFS/ECENS). This results in an overall more amplified pattern over the CONUS by the middle of next week with troughing over the West and East around a building heat dome over the Four Corners and into the Plains. ...Weather/Hazards Highlights... The heat wave continues through Sunday for the Northwest/Great Basin. Relief comes in the form of an upper trough around Sunday night, though this shifts the anomalous heat east across the northern Plains through the first half of next week. Above normal temperatures continue for the southern Plains and Southeast through the next week. A quasi-stationary boundary draped from the south-central Plains to the southern Mid-Atlantic will continue to focus a threat for heavy to excessive rainfall Saturday night into Monday with likely repeated rounds of heavy rainfall increasing the risk for localized flash flooding. The days 4 and 5 experimental EROs continue to have have expansive slight risks depicted along this boundary from the central Plains, across the TN Valley/southern Appalachians and the southern Mid-Atlantic. Meanwhile, persistent monsoonal moisture will continue to support diurnally favored showers/storms with locally heavy to excessive rainfall over an already very soggy Four Corners and southern Rockies region through next week. Jackson Hazards: - Heavy rain across portions of the Central Plains, the Central Rockies, the Lower Mississippi Valley, the Central Great Basin, the Tennessee Valley, the Southern Rockies, the Middle Mississippi Valley, the Mid-Atlantic, the Southern Appalachians, the Southeast, the Southern Plains, the Ohio Valley, and the Southwest, Sat, Jul 30. - Heavy rain across portions of the Southern Rockies and the Southwest, Sat-Wed, Jul 30-Aug 3. - Heavy rain across portions of the Lower Mississippi Valley, the Central Appalachians, the Tennessee Valley, the Middle Mississippi Valley, the Mid-Atlantic, the Southern Appalachians, the Southeast, and the Ohio Valley, Sun-Mon, Jul 31-Aug 1. - Flooding possible across portions of the Southern Appalachians, the Mid-Atlantic, the Central Appalachians, the Ohio Valley, and the Tennessee Valley. - Flooding occurring or imminent across portions of the Middle Mississippi Valley and the Northern Plains. - Flooding likely across portions of the Middle Mississippi Valley. - Excessive heat across portions of California, the Central Great Basin, the Pacific Northwest, the Northern Rockies, and the Northern Great Basin, Sat-Sun, Jul 30-Jul 31. - Excessive heat across portions of the Lower Mississippi Valley and the Southern Plains, Sat-Wed, Jul 30-Aug 3. - Excessive heat across portions of the Central Plains, the Lower Mississippi Valley, the Northern Plains, the Tennessee Valley, the Middle Mississippi Valley, the Upper Mississippi Valley, and the Ohio Valley, Mon-Wed, Aug 1-Aug 3. 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