429 FXUS02 KWBC 030804 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 404 AM EDT Fri Jul 3 2026 Valid 12Z Mon Jul 06 2026 - 12Z Fri Jul 10 2026 ...Major Heatwave to settle over the South/Southeast next week... ...Pattern Overview... Broad upper-level ridging builds across 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. Mean troughing persists across the Northwest. ...Guidance/Predictability Assessment... Models are in reasonably good agreement on the synoptic evolution of the mid-level pattern across the CONUS next week. A general model blend consisting of the available deterministic and Ai guidance was used on days 3 and 4. This was followed by a gradual increase in ensemble means since the UKMET and Euro AIFS produced an overamplified trough over the Midwest compared to the other pieces of guidance. ...Weather/Hazards Highlights... A major heatwave ensues across the South/Southeast later this weekend and through 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. A surface low pressure system moving through the East will promote scattered to isolated thunderstorms in the Northeast/Mid-Atlantic early next week. Some of the storms may generate excessive rainfall from the Lower Mississippi Valley to the Northeast on Monday. Storms along with the heavy rain threat shift south into portions of the Southeast on Tuesday as the attendant cold front drifts into the South then stalls out. Another system in the Northern Plains may produce some additional storms with potential for some isolated instances of flash flooding on Tuesday. 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 $$