351 FXUS02 KWBC 250714 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 314 AM EDT Tue Aug 25 2026 Valid 12Z Fri Aug 28 2026 - 12Z Tue Sep 01 2026 ...Hazardous Heat from the Desert Southwest to the Southern Plains to reposition from the South-Central U.S. to the Mid-South... ...Overview... The resilient upper level pattern will feature troughing in the Northwest and East and a strong ridge anchored over the Southwest this week. The ridge will flatten late this week as upper level troughing strengthens over the Northwest, but hazardous heat will persist from the Desert Southwest to the southern Plains. The closed high/ridge will reposition eastward this weekend, resulting in expanding heat especially across the south-central U.S. and Mid- South. Moisture on the western periphery of the ridge will support daily monsoonal convection over portions of the Southwest and Intermountain West/Rockies. Meanwhile, several frontal systems will push through the upper troughs, bringing showers and thunderstorms from the northern/central Plains far down into the East/Southeast. ...Guidance/Predictability Assessment... Guidance remains in overall good agreement on the synoptic weather pattern, albeit with renewed uncertainty with the timing of systems working through the Northwest to the U.S. northern tier. Given continued larger scale agreement, favor a composite model/ensemble mean/machine learning guidance solution that seems to provide a good general forecast and threat messaging baseline in line with continuity. The blend process tends to mute/mitigate embedded smaller scale system differences as consistent with individual predictability, but maintains main focusing features. ...Weather/Hazards Highlights... Under the influence of the upper high/ridge this week, daily maximum temperatures across the southern Plains will continue to rise into the 90s and 100s with oppressive heat indices. Record- breaking warm overnight temperatures across the southern tier will further limit recovery from the heat, resulting in widespread Major to Extreme HeatRisk that may cause heat related illnesses. As the upper ridge flattens into this weekend and shifts eastward into early next week, hazardous heat will refocus over the Southern Plains and steadily expand north across the south-central U.S and Mid- Lower Mississippi Valley/Mid-South along with the main closed high. For the Desert Southwest, daily max temperatures are forecast to soar into the 110s, which will create heat concerns this week. Please see WPC's Key Messages for more extreme heat details. Monsoonal moisture streaming northward on the western periphery of the upper ridge and ahead of Northwest U.S. upper troughing will continue to fuel scattered, diurnally driven convection from the Southwest and Intermountain West to the Rockies. Individual cells may lead to isolated instances of flash flooding for sensitive locations such as burn scars, favored terrain like slot canyons, and urban areas. Marginal Risk areas cover portions of these broad areas on the WPC Day 4/Friday and Day 5/Saturday Excessive Rainfall Outlooks (EROs). Shortwaves rounding the top of the ridge and pivit into the downstream mean upper trough while interacting with wavy frontal systems to periodically trigger showers and strong to severe thunderstorms from the Plains to the Midwest where Marginal Risk EROs have been introduced for Friday and Saturday. Heavy rainfall potential may renew over the northern Plains and Midwest later weekend into next week with organized low/frontal system approach. Meanwhile downstream, ERO Marginal Risk areas highlight a protracted threat for especially the coastal Southeast that may see repeated rounds of locally heavy precipitation as wavy frontal boundaries approach and ultimately stall over these moist regions. 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 $$