950 FXUS02 KWBC 101823 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 223 PM EDT Fri Jul 10 2026 Valid 12Z Mon Jul 13 2026 - 12Z Fri Jul 17 2026 ...Dangerous heat spreads from the Intermountain West to the northern Plains and Upper Midwest through next week... ...Overview... A broad and anomalously strong upper-level ridge will be in place across the Intermountain West to north-central U.S. next week, leading to a significant and dangerous heat wave continuing across those regions. Rain and thunderstorm chances will mainly occur across southern states to the south of the ridge, though some northern tier rain/storms rounding the ridge are possible as well. Additionally, monsoonal moisture is forecast to increase and produce showers and storms across the Southwest and Four Corners states. ...Guidance/Predictability Assessment... The model suite remains in good agreement through the first portion of the period with relatively small spread regarding the broad upper- level ridge and high north- central U.S. By midweek, the ensemble spread gradually increases as the shortwave energy moves across southward of the ridge. This will bring some uncertainty with timing and amplitude of associated surface frontal features, but the ensemble means continue to depict the overall synoptic pattern. Toward the later portion of the period, uncertainty grows as models diverge with the large-scale features over western and southern U.S., as well as the progression of the northern stream energy. ECMWF continues to show a slower progression of the upper trough moving into the Northwest, while the CMC and GFS shows a more reasonable solution. Ensemble means from the GEFS and ECENS provide the most stable depiction of the large- scale pattern and help smooth out run- to- run variability from the deterministic models. Therefore, the forecast was based on a blend of the GFS, ECMWF, CMC, ECAIFS, and UKMET for the first portion of the period, while incorporating the ensemble means for the latter portion. ...Weather/Hazards Highlights... A strong and expansive ridge sprawling from the western U.S. to the central U.S. will lead to an extended period of dangerous heat for parts of the Intermountain West, northern Plains, and Upper Midwest through most of next week. Several days of well above normal and potentially record-breaking maximum and minimum temperatures will lead to widespread major to extreme HeatRisk. WPC continues to update Heat Key Messages for this event, which can be found on our homepage. Farther east, periods of warmer than average temperatures are likely for the Northeast particularly on Tuesday, shifting into the Mid-Atlantic midweek and beyond while the Northeast cools behind a cold front. Meanwhile, much of the southern tier could see near to slightly below average temperatures as a front stalls near the Gulf Coast and acts as a focus for showers and thunderstorms through at least midweek. The very moist and unstable environment could lead to flash flooding concerns, and Marginal to Slight Risks of flash flooding are in place for Days 4-5 (Monday-Tuesday). By the latter part of next week, subtropical ridging is forecast to build into Florida, where temperatures should stay warm and elevated HeatRisk is forecast. Increasing southerly flow around the western periphery of the central U.S. ridge will draw monsoonal moisture into the Southwest and the central Great Basin early next week. This moisture will lead to scattered to numerous showers and thunderstorms with the potential to produce heavy rainfall and localized flash flooding. Sensitive places such as burn scars, steep terrain, etc., would be the most vulnerable to any flooding concerns that may develop. Marginal Risks of excessive rainfall are delineated for Monday in the Southwest and expanding toward the Four Corners Tuesday, and the rainfall potential is forecast to continue expanding northeastward as the week progresses. Oudit/Tate 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 $$