112 FXUS02 KWBC 041820 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 220 PM EDT Sat Jul 4 2026 Valid 12Z Tue Jul 07 2026 - 12Z Sat Jul 11 2026 ...Major Heatwave to settle over the Southern Tier next week... ...Pattern Overview... Broad upper-level ridging is forecast to build over the Southern U.S. next week while transient shortwaves propagate through the Great Lakes and Northeast/Mid-Atlantic. The southern ridge will support a major heatwave initially over the South/Southeast then building into the Southwest/Great Basin. Troughing along the U.S.-Canadian border will promote diurnal showers and thunderstorms from the Northern Plains to the Northeast, with a focused risk for heavier rain over the Upper Midwest into the Great Lakes Tue-Wed. Troughing over the Northeast Pacific will maintain near to below average temperatures in the Pacific Northwest. ...Guidance/Predictability Assessment... Models and ensembles were in mostly good agreement regarding the evolution of the synoptic pattern next week. There was a budge faster in the northern stream flow compared to the previous forecast, but overall continuity was good. Differences among the deterministic models generally fell within the typical range for mid-summer. ...Weather/Hazards Highlights... A major heatwave will ensue across the South/Southeast and Southwest next week as weak upper ridging/quasi-zonal flow is expected to persist south of transient shortwaves propagating through the Northeast/Mid-Atlantic. The aforementioned troughing will pull warm and moist air across the Southeast and generate daily heat indices between 105-110 degrees from eastern Texas to the Mid-Atlantic/Southeast Coast next week. These conditions will be dangerous and likely impact some health systems, heat sensitive industries, and infrastructure. This level of heat will also affect those without adequate cooling and/or hydration. Surface waves and attendant fronts draped across the Northern Plains and Upper Midwest will be the focus for scattered thunderstorms on Tuesday and Wednesday. Well above normal moisture (>90th percentile) and instability along the front could combine to produce heavy rainfall/flash flooding, but weak shearing will likely mitigate a severe weather threat. Rain showers and thunderstorms will move into the Eastern U.S. later in the week into next weekend. Lastly, monsoonal moisture may start to increase over at least Arizona late next week into the weekend as the upper high drifts a bit farther north into Utah. Fracasso/Kebede 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 forecast, excessive rainfall outlook, winter weather outlook probabilities, heat indices and Key Messages 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 https://www.wpc.ncep.noaa.gov/#page=ovw $$