219 FXUS02 KWBC 171813 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 213 PM EDT Fri Jul 17 2026 Valid 12Z Mon Jul 20 2026 - 12Z Fri Jul 24 2026 ...Dangerous heat will gradually subside in the north-central U.S. early next week, but linger over a humid U.S. southern tier... ...Overview... An amplified upper ridge over the western and central U.S. will cause dangerous heat across the northern/central Plains into early next week. The northeast side of the ridge will get gradually suppressed by shortwave energy entering the Midwest/Great Lakes into a northeastern U.S. upper trough, which will bring relief from the heat to northern areas as the trough pushes cold fronts through the region. Very hot and humid conditions will linger next week over much of the U.S. southern tier. The shortwaves and fronts in the upper trough should also yield rounds of heavy rains and strong to severe thunderstorms from the Great Lakes to the East Coast next week. Additionally, ample monsoonal moisture will continue to stream into the Southwest and Intermountain West/Rockies to fuel rounds of enhanced showers and thunderstorms. ...Guidance/Predictability Assessment... Models remain generally agreeable on the large scale pattern through the period, but still considerable uncertainty in the details. One notable area is with a shortwave that drops into the Northeast trough to deepen it early to mid week. The ECMWF remains deeper/sharper with this shortwave, which deepens the trough overall a bit more than consensus. In the Gulf, models show considerable uncertainty with possible energy in/near the northeast Gulf which could move inland at the start of the medium range period. NHC is monitoring this area currently with low probability of formation, but regardless if it develops true tropical characteristics, there is confidence for enhanced rainfall across parts of the Florida and the Southeast into next week. The WPC forecast for today used a non-ECMWF blend for the first half of the period, transitioning to half ensemble means/half deterministic guidance by Day 7. ...Weather/Hazards Highlights... Heatwave focus over the northern/central Plains is expected to ease some early next week. This occurs as supporting upper ridge influence shifts farther south leading to generally Major HeatRisk stretching from the central Plains and Middle/Lower Mississippi Valley to Southeast for next week. Temperatures a few degrees above already warm averages combined with high humidity could lead to increased HeatRisk in the south-central U.S. and Gulf Coast states. WPC is doing Key Messages for this, please refer to those for the latest information. Meanwhile, the southwestern to south-central U.S. could see slightly below average temperatures as ample moisture leads to clouds and rain/thunderstorms. Flow under the upper ridge will draw significant monsoonal moisture into the Southwest and Intermountain West to the Rockies. 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. Broad Marginal Risks of excessive rainfall are in place from the Southwest across much of the Intermountain West Monday/Tuesday. Coverage of showers and thunderstorms should gradually increase eastward over the Rockies/Plains next week to monitor. Elsewhere, southern stream energy is forecast to meander in the northeastern Gulf in a moist and unstable environment early next week as being monitored by NHC. Troughing and tropical moisture in place (even if there is no true tropical low) could lead to heavy rain, and Marginal Risks are in place from north-central Florida to the coastal Southeast for isolated flash flooding Monday. The next round of potential heavy rains and strong to severe thunderstorms are forecast to come through the Midwest and Great Lakes early next week with digging of an energetic shortwave aloft and vibrant wavy frontal push. As the upper trough position amplifies and the fronts work southeast Tuesday/Wednesday, heavy convective rain chances will overspread much of the East, settling into the Southeast later next week with moderating wavy frontal progression. A WPC Excessive Rainfall Marginal Risk area was introduced for Tuesday for the Mid-Atlantic and the Northeast. Santorelli/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 $$