FOUS30 KWBC 070816 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 416 AM EDT Sun Jun 7 2026 Day 1 Valid 12Z Sun Jun 07 2026 - 12Z Mon Jun 08 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF THE MID-MISSISSIPPI VALLEY, OZARKS, AND WESTERN TENNESSEE VALLEY... Numerous thunderstorms are expected to form this afternoon into tonight over a broad area spanning across the Great Plains and Mississippi, Ohio, and Tennessee Valleys. Three primary forcings will trigger storms: an upper level shortwave moving north across the central Plains, Mid-Mississippi Valley, and Upper Midwest, a strengthening cyclone emerging in the northern/central Plains, and a quasi-stationary frontal boundary draped across the Mid- Mississippi and Ohio Valleys. These features will interact with a moist, unstable air mass that will support efficient rainfall processes that could lead to heavy rainfall. Deep, moist southerly flow has primed the atmosphere across the Plains and Mississippi Valley, increasing PWAT values to around 2 inches (2-2.5 standard deviations above normal for this time of year). Hi-res CAM guidance suggests rainfall rates of 2-4 inches per hour will be possible in thunderstorm cells across the Mid-Mississippi Valley and portions of the Ozarks and western Tennessee Valley, which would exceed current flash flood guidance and result in scattered instances of flash flooding within the Slight Risk area. Areas from eastern Oklahoma into western Arkansas and east-central Illinois into west- central Indiana may be more susceptible to flash flooding after rainfall yesterday left soils thoroughly saturated. Heavy rain will likely result in locally high rainfall totals, potentially reaching 5-7 inches for some locations within the Slight Risk area. Locally heavy rainfall will also extend along the quasi-stationary frontal boundary into Ohio Valley. Storms forming along the boundary will have the potential to produce rainfall rates over 2 inches per hour, and storm motion will be fairly slow. However, convection should be more isolated over the Ohio Valley portion of the front, resulting in only a Marginal Risk. Stronger convection will also be possible in the vicinity of the low pressure system over the northern Plains, but storms will be much more progressive in this region, which will limit heavy rainfall potential and the risk of flash flooding. The Marginal Risk area extends across the northern Plains to account for isolated flash flood potential with stronger thunderstorms that may form. Dolan Day 2 Valid 12Z Mon Jun 08 2026 - 12Z Tue Jun 09 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE MID-MISSISSIPPI, LOWER OHIO, AND TENNESSEE VALLEYS... On Monday, the northern stream cyclone will move north into Canada, which will lift the previously stationary frontal boundary north across the Upper Midwest and Great Lakes as a warm front and push the tail end of the front south into the Carolinas. Heavy rainfall potential will be focused in the warm sector of the system over the Mid-Mississippi, lower Ohio, and Tennessee Valleys where a very moist and unstable air mass will still be in place. A splitting upper level shortwave will push some energy across these regions, which will support a broad area of widespread/numerous thunderstorms. With weakening steering flow, storm motions are expected to become very slow, which will heighten the threat of flash flooding. The RRFS shows modest probabilities (20-40%) of hourly rainfall rates exceeding 2 inches per hour for several hours across the Slight Risk area. Some of these areas will also receive heavy rainfall during the day 1 period, which may increase the risk of flash flooding if areas are impacted by additional storms with heavy rainfall on Monday. Outside of the Slight Risk area, a broad Marginal Risk area extends into the Upper Midwest and central Plains. Anomalous moisture will surge north behind the lifting warm front, which will support locally heavy rainfall that may lead to isolated instances of flash flooding for the western Great Lakes states. Models have also started consistently showing a potential MCS forming underneath a potent upper level shortwave moving quickly east across the central Plains on Monday evening. Though this feature would likely be progressive, it could have the potential to produce heavy rainfall and isolated flash flooding. There is still some uncertainty regarding the location of this feature, resulting in a broad Marginal Risk area that will likely be narrowed down over the next few forecast cycles. Dolan Day 3 Valid 12Z Tue Jun 09 2026 - 12Z Wed Jun 10 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE UPPER MIDWEST AND OHIO AND TENNESSEE VALLEYS... On Tuesday, an upper level trough will move across the northwestern U.S. and support cyclogenesis over the northern Plains. A wave of convection is expected to form ahead of the developing cyclone, bringing thunderstorms to much of the Upper Midwest. A moist and unstable air mass will be in place across the Upper Midwest after a warm front lifts north on Monday, which will support heavy rainfall in thunderstorms. Flash flood potential should be limited by the progressive nature of this system, but locally heavy rainfall could still lead to isolated instances of flash flooding, especially where soils will be moistened from rainfall expected on Sunday and Monday. A Marginal Risk area seems sufficient to cover the flash flood threat at this time. Another Marginal Risk area is in place for much of the Ohio and Tennessee Valleys and portions of Michigan where a slow moving frontal boundary will linger through Tuesday. This frontal boundary will provide modest lift/support for scattered convection across these regions. An anomalously moist air mass will still be in place, which should be enough to support locally heavy rain in some stronger storms and may lead to isolated instances of flash flooding. The flash flood threat will be significantly lower for these regions than on Monday with much weaker synoptic support. Dolan Day 1 threat area: https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt Day 2 threat area: https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt Day 3 threat area: https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt