798 FXUS02 KWBC 100709 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 309 AM 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... Model guidance shows good agreement in terms of the 594+ dm upper high centered near the north-central U.S. and meandering next week, leading to high confidence in multiple days of hazardous heat. The ridge may stretch into the East at times, after a Northeast trough moves away Monday and to the south of another trough moving in by the latter half of the week. Smaller-scale energies to the south of the ridge are relatively more uncertain, and cause some variance in QPF, but within reason for the medium range period. The primary synoptic scale model differences are on the northwestern side of the ridge. By Tuesday-Wednesday, northeastern Pacific energy forming an upper low/trough shows differences in placement. With the newer 00Z guidance, the ECMWF is now pretty much alone in its farther west position compared to other dynamical and AI guidance. With the previous 12Z cycle, the CMC was similar to the EC, but the 00Z CMC has jumped east and now aligns well with the GFS, AIFS/AIGFS, and ensemble means. Thus preferred a blend of the deterministic and ensemble guidance other than the ECMWF, and with near half ensemble means for the model blend for Days 6-7 to mitigate individual model differences. ...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. 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 $$