462 FXUS02 KWBC 060654 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 254 AM EDT Mon Jul 6 2026 Valid 12Z Thu Jul 09 2026 - 12Z Mon Jul 13 2026 ...Major Heatwave focus over the Southeast U.S. and building over the Southwest/West-Central U.S. through this week and beyond... ...Pattern Overview... An upper-level ridge develops over the Central U.S. through this weekend, while a series of shortwaves move through the Great Lakes and Northeast/Mid-Atlantic. This pattern will promote a major heatwave across the Southern U.S.. Mean troughing keeps temperatures at or below average across the Eastern Pacific/Pacific Northwest. ...Guidance/Predictability Assessment... Models are in reasonably good agreement regarding the 500 mb pattern across the CONUS during the medium range period. A general model blend consisting of most of the available deterministic and Ai guidance is used on days 3 and 4 before ensemble means are gradually incorporated into the blend through the rest of the period. ...Weather/Hazards Highlights... A major heat wave is expected to expand beneath a growing upper- level ridge in the Central/Southern U.S.. This heat wave will spread from the Southeast to the Southern Plains and into the Central Rockies by the weekend. Heat indices between 105-115 are expected across the South. Troughing in the Northeast/Mid-Atlantic will support continued hot/moist southerly flow into the Florida Peninsula, in particular, where there's a growing concern for extreme heat risk beginning on Wednesday and continuing into the weekend. No overnight relief from hot temperatures will affect anyone without adequate cooling/hydration as well as health systems, industries and infrastructure. Scattered showers and thunderstorms will gradually spread south through the Mississippi Valley, Midwest and Mid- Atlantic before stalling out over the South late this week and into the weekend. Meanwhile, monsoonal moisture may start to increase over at least Arizona late-week/weekend as the upper high lifts farther north into Utah/Colorado. Ridge amplification may also lead to some downstream strong convection for the Southern Rockies/Plains given summertime airmass and growing upper diffluence/weaknesses. 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 $$