548 FXUS02 KWBC 040653 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 253 AM EDT Sat Jul 4 2026 Valid 12Z Tue Jul 07 2026 - 12Z Sat Jul 11 2026 ...Major Heatwave to settle over the South/Southeast next week... ...Pattern Overview... Broad upper-level ridging builds 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, while the troughing to the north will generate diurnal showers and thunderstorms from the Northern Plains to the Northeast. Mean troughing persists across the Northwest. ...Guidance/Predictability Assessment... Models are in mostly good agreement regarding the evolution of the synoptic pattern next week. The GFS was favored in the blend in part because it clusters well with the ensemble means. The deterministic Canadian wasn't included at all due to it overamplifying a Central U.S. trough and not capturing the timing and intensity of northern tier shortwaves compared to model consensus. ...Weather/Hazards Highlights... A major heatwave ensues across the South/Southeast next week as weak upper ridging/quasi- zonal flow persist south of transient shortwaves propagating through the Northeast/Mid-Atlantic. The aforementioned troughing will pull warm and moist air through 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 to isolated thunderstorms on Tuesday and Wednesday. Sufficient moisture (3-4 stndv) 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 move into the Eastern U.S. later in the week. 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 $$