FOUS30 KWBC 090100 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 900 PM EDT Mon Jun 8 2026 Day 1 Valid 01Z Tue Jun 09 2026 - 12Z Tue Jun 09 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE CENTRAL PLAINS INTO THE OZARKS AND FROM PARTS OF THE UPPER MIDWEST TO THE LOWER OHIO AND WESTERN TENNESSEE VALLEYS... For the 01Z Update, removed the southern portion of the Slight Risk that extended into the Southeast. Showers and storms continue to fall across portions of northern Alabama, Georgia, and eastern Tennessee and they may present some additional isolated issues given the wet antecedent conditions. However, rates have generally been on the decrease across this region, and lacking any strong forcing and low level inflow, coverage and rates are expected to continue to diminish with the loss of daytime heating. Maintained the Slight Risk farther to the north, extending from western Tennessee to central Wisconsin. Benefiting from stronger forcing associated with a well-defined shortwave and sufficient southwesterly low level inflow, storms are expected to persist further into the evening within this area, with pockets of heavy amounts expected. Both the HREF/REFS show higher probabilities for additional accumulations of 2 inches over across portions of southern Illinois/Indiana, as well as central Wisconsin. The heaviest amounts of the evening and overnight may occur across central into eastern Kansas. Supported by strengthening low level inflow, a complex now developing over north-central Kansas is expected to further organize as it moves east-southeast across eastern Kansas into Missouri overnight. This will followed by the storms now drifting east across northeastern Colorado, taking a similar track across Kansas, resulting in a stripe of heavy accumulations overnight. Recent runs of the HRRR and HREF are in generally good agreement, presenting a signal for 3+ inch amounts extending from portions of north-central into eastern Kansas. Pereira Day 2 Valid 12Z Tue Jun 09 2026 - 12Z Wed Jun 10 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE NORTHERN PLAINS AND WESTERN KENTUCKY AND TENNESSEE... 20Z Update... The inherited threat areas in the Northern Plains and Upper Mississippi Valley were adjusted based on latest WPC QPF and 12Z HREF probabilistic guidance. The primary change this forecast cycle was to expand the Slight Risk in the Mid-South farther south and east into the TN Valley and southern Appalachians. Latest 12Z guidance has shown a gradual southward expansion in the QPF field, which aligns well with where the highest PWs (around 2.0" PWs) and instability will be located. A sheared 500mb trough tracking towards the Southeast will also promote healthy upscale ascent over an area with very sensitive soils. The 12Z HREF/REFS probabilistic guidance shows moderate-to-high chances (50-70%) for rainfall totals >3" in northern GA and parts of the western Carolinas. In addition, farther north, the same 12Z HREF/REFS guidance shows low chance probabilities (20-40%) in central KY and northern TN. These areas under what would be considered the "high-end Slight" section within the larger Slight Risk area in the Mid-South. CAMs guidance is more on the southern envelope of QPF rather than global models which are farther north. Still, some CAMs members show some locally significant rainfall totals where back-building and training storms occur. The northern Plains and Upper Mississippi Valley threat areas had minor adjustments based on latest guidance, but otherwise no additional threat areas were proposed this cycle. Mullinax ---Previous Discussion--- On Tuesday, a potent upper level trough will move across the northern Rockies and emerge into the northern Plains. This trough will spur cyclogenesis over the northern Plains while a low level jet increases moisture and instability ahead of the system. The environment will be ideal for supercell development Tuesday afternoon, and increasing shear over the region will allow storms to evolve into an MCS Tuesday evening into Tuesday night. Deep convection within these severe storms will be able to tap into moisture in the atmosphere (PWAT values 1.5-2 inches) and create very heavy rainfall. The quick nature of the MCS should somewhat limit the risk of flash flooding, but intense rainfall rates in excess of 2 inches per hour will exceed FFGs and could lead to impactful flash flooding, especially in urban areas. A Slight Risk area has been introduced for much of central and eastern North Dakota and northwestern Minnesota. Scattered showers and storms are forecast from the southern Appalachians and Tennessee Valley through the Ohio Valley and Great Lakes region, which will be supported by an upper level shortwave lifting northeast across the Ohio Valley and Great Lakes and a slow moving warm front extending south into the Tennessee Valley and southern Appalachians. The air mass in place will be anomalously moist (PWATs around 2 inches) and sufficiently unstable to support locally heavy rainfall. Available hi-res guidance suggests higher rainfall totals will be possible across western Kentucky and Tennessee where convection will continue from the Day 1 period into Tuesday morning. A mid-level shortwave will be enhancing this convection and should allow for efficient rainfall rates over 2 inches per hour. A Slight Risk area has been introduced to cover the elevated flash flood threat over western Kentucky and Tennessee. Global models have also been showing locally enhanced rainfall totals over portions of the Ohio Valley, but there is still a significant amount of uncertainty in the location of these higher totals. It is possible the Slight Risk area may need to be expanded to the northeast as convective details become more clear with additional hi-res guidance available later today. Dolan Day 3 Valid 12Z Wed Jun 10 2026 - 12Z Thu Jun 11 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM EASTERN KANSAS INTO NORTHERN MISSOURI AND SOUTHERN IOWA... 20Z Update... The inherited risk areas remain in good shape and the rationale provided from the previous shift remains on track. Did adjust the Slight Risk a little farther south and west to account for typical QPF biases in global guidance that tend to be too far north. But otherwise, no significant changes were made this forecast cycle. Mullinax ---Previous Discussion--- On Wednesday, the northern Plains cyclone will be moving swiftly east and pushing a cold front across the Midwest. Showers and thunderstorms are expected ahead of and along the frontal boundary from the Midwest to the central Plains, which are encompassed by a Marginal Risk of excessive rainfall. The tail end of the front will likely hang up on the Rockies and flatten out over the central Plains, and low pressure is expected to develop over Kansas where a dryline will intersect the boundary. Models are showing impressive moisture transport ahead of the frontal boundary Wednesday morning and a secondary surge Wednesday night as a strong low level jet brings increasing moisture and instability into the central Plains. This set up will be conducive for heavy rainfall, and global models are showing potential for heightened rainfall totals of 2-4 inches within the Slight Risk area, which may be underdone given the convective limitations of the models. Locally heavy rainfall may also be possible over central Wisconsin and could impact areas highlighted with a Slight Risk on Day 2, which could warrant an additional Slight Risk upgrade. However, there is much more uncertainty regarding rainfall totals in Wisconsin, which may be limited by the progressive nature of the cold front. 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