033 FXUS02 KWBC 052013 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 413 PM EDT Sun Jul 5 2026 Valid 12Z Wed Jul 08 2026 - 12Z Sun Jul 12 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... Upper-level ridging will persist over the Southeast and also build robustly through the next week from the Southwest to across much of the west-central U.S.. This will support a major heatwave initially over the South/Southeast and increasingly from the Southwest/Great Basin to the Rockies/Plains this week and beyond. Transient shortwaves will propagate across the U.S. northern tier on/into the northern periphery of the ridge. Troughing along the U.S./Canadian border will promote showers and thunderstorms from the Northern Plains to the Midwest and Northeast, with a focused risk for heavier rain and runoff issues from the Upper Midwest into the Great Lakes Tuesday and Wednesday where WPC Excessive Rainfall Outlook Marginal to Slight Risk areas have been issued. Wavy frontal system translation and enhanced rainfall/thunderstorm activity focus should shift southward and broadly spread across the east-central to eastern U.S. late week/next weekend under an amplfying upper trough position downstream of the main upper ridge. ...Guidance/Predictability Assessment... Guidance seems in reasonably good agreement on the mid-larger scale flow pattern this week. Favor a blend to mitigate smaller scale variances as consistent with individual predictability with more focus on the models Wednesday/Thursday before shifting focus to the ensmeble means and machine learning guidance into next weekend. This also acts to maintain good WPC product continuity. ...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. Surface waves and attendant fronts draped across the Northern Plains and Upper Midwest/Great Lakes will be the focus for scattered thunderstorms on Wednesday. Well above normal moisture (>90th percentile) and instability along the front could combine to produce heavy rainfall/flash flooding. Rain showers and thunderstorms will shift in mass mainly into the east-central and eastern U.S. later in the week and into next weekend. Meanhile, monsoonal moisture may start to increase over at least Arizona late next 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/Schichtel 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 $$