488 FOUS30 KWBC 080050 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 850 PM EDT Tue Jul 7 2026 Day 1 Valid 01Z Wed Jul 08 2026 - 12Z Wed Jul 08 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE NORTHERN PLAINS, UPPER MIDWEST AND SOUTHERN MID-ATLANTIC... ...Mid Atlantic... Elevated PWATs above 2" and the presence of a cold front across southern and southeast VA has led to a focus of enhanced convection across the area. Significant hourly rates are the driver behind any flash flood prospect as weak shear coupled with modest buoyancy allows for pulse type convection with slow cell motions. Outflows generated by storms have allowed for local initiation of thunderstorms considering how favorable the environment is across the region. This setup is also conducive for heavy rain prospects all the day into NC where current radar/sat composite indicate a strong cluster of thunderstorms already impacting the Raleigh metro. This will continue for another few hours before the loss of diurnal instability will eventually degrade any activity in the area. This goes for areas of VA as well, so the SLGT risk was maintained in these areas with the best prospect for flash flooding likely to occur in the window between 00-06z. The SLGT risk was expanded to include the Raleigh metro due to the ongoing heavy rainfall and flash flood warnings in effect with potential impacts lingering for another few hours. ...Northern Plains to Upper Midwest... Energetic shortwave analyzed upstream over eastern MT into the western Dakotas will aid in the maturation of a round of strong to severe thunderstorms across eastern ND/SD, extending through MN with activity eventually propagating east and southeast into WI overnight. CAMs have been consistent with the signature of this convective initiation along a front draped over the region. Increased convergence along the front will stem from a combination of frontal enhancement and the nose of an 850mb LLJ entering into the area. Flow aloft will align parallel to the front with shear provided via a 50kt jet max at 500mb. Deep moisture pool across the Northern Plains and Midwest is present with PWATs between 1.7-2.0", verified via the 00z KMPX sounding running at 1.93" PWATs as of the 08/00z RAOB. HREF probs continue to highlight central MN as the focal point, however, hourly CAMs such as the HRRR have inferred that the area over northeast SD down through south-central MN may end up as the primary target, or at least provide a secondary maxima as they align within the quasi- stationary front in place, and storm motions move into the warm sector and better localized shear overnight. No matter the case, the environment is ripe for locally enhanced rainfall with hourly rates likely to reach 2-3"/hr in the strongest cell cores leading to rainfall totals between 3-5" in spots across the region. More on this setup can be reviewed with the latest MPD #0642 issued over the area of interest. The previous SLGT risk was generally maintained with just a minor expansion to the east in WI, and a nudge south on the southern flank of the inherited risk. Kleebauer Day 2 Valid 12Z Wed Jul 08 2026 - 12Z Thu Jul 09 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE UPPER MISSISSIPPI VALLEY/UPPER GREAT LAKES... 20Z Update... The previously issued outlook still in good shape. Even though there were a couple of minor adjustments...there was no fundamental shift in the forecast reasoning. Previous Excessive Rainfall Discussion... ...Central Plains to the Upper Great Lakes... Several locations remain sensitive given recent rains and lowered FFGs, particularly for portions of the Upper Mississippi Valley and Upper Great Lakes. A Slight Risk area remains warranted for this part of the country where areal averages of 1-2 inches are expected with localized swaths of 3+ inches. Convection from overnight may be weakening during the morning hours however redevelopment near the frontal boundary midday should occur over Minnesota and Wisconsin. Approaching shortwave energy and an upper level jet will help drive this uptick in activity, with PWs above the climatological 90th percentile and CAPE approaching 2000 J/kg supporting heavy rainfall rates. While a progressive squall line should eventually evolve, there will be an opportunity for some training and backbuilding during the development and initial upscale growth phase of convection. A Marginal Risk spans from the Central Plains to the Great Lakes and surrounding area. ...Tennessee/Ohio Valley to the Mid-Atlantic... A Marginal Risk was maintained for this region. A shortwave moving across Kentucky/Tennessee and a lingering backdoor front over West Virginia/Virginia should both act as a focus for convective development. Not expecting anything too organized or widespread, but enough moisture and instability will be around to support locally heavy rainfall rates. Campbell Day 3 Valid 12Z Thu Jul 09 2026 - 12Z Fri Jul 10 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE NORTHERN/CENTRAL PLAINS, MIDWEST, OHIO/TENNESSEE VALLEYS AND GREAT LAKES REGION... Stronger flow will initially remain along the northern tier of the CONUS early to mid-week with mean upper-ridging across the western to central United States. Embedded shortwaves rounding the upper- ridge will eventually lead to deepening troughing across the the Midwest and adjacent areas on Thursday. The southward shift of stronger flow aloft into the Central Plains east through the Middle Mississippi/Ohio/Tennessee Valleys and Lower Great Lakes will bring a better chance for scattered thunderstorms across the region. Seasonably high instability and moisture pooling southward of a wavy cold front will support locally heavy rainfall rates with training potential over the region. That will compound impacts from convection the previous forecast period. A large area of 1-2 inch areal average totals with embedded higher amounts positioned over the southern-third of Illinois/Indiana/Ohio through much of Kentucky into West Virginia. This is coincident with the progression of both the front and a strengthening shortwave trough migrating out of the Central Plains into the region as we move into Friday. Machine Learning output is also favoring the Ohio River Basin into the Central Appalachians extended from southwestern Pennsylvania down through West Virginia as terrain influences along with the synoptic evolution will couple into a targeted threat for heavy rainfall and local maxima sufficient for scattered flash flood prospects. Bann Day 4 and Day 5 Valid 12Z Fri Jul 10 2026 - 12Z Sun Jul 12 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE OHIO/MID-MISSISSIPPI VALLEYS AND CENTRAL APPALACHIANS ON FRIDAY AND SATURDAY... ...Ohio and Mid-Mississippi Valley's... 20Z Update: The previous forecast was generally maintained with the overall synoptic pattern still maintaining continuity in the proposed evolution at both the upper levels and at the surface. Ensembles continue to indicate a multi-day bout of heavy rainfall across the Mid-Mississippi to Ohio Valley in conjunction with both mid-level ascent and the proxy of a cold/quasi-stationary front that will aid in scattered to widespread convective activity in-of a very moist environment positioned over the region. The trends in guidance indicate a bit more emphasis further west into MO with even the D4 showing an extension of heavy rain prospects back into the Southern High Plains thanks to a likely convective complex developing around the eastern flank of a strengthening ridge over the Four Corners. Classic summer pattern materializing for areas west of the Mississippi, so the threat for isolated flash flooding will likely have some footing in the extended with D4 the first prospectus day for the threat. The SLGT risk inherited was expanded into the Mid-Mississippi area of eastern MO on D4 and across southern MO on D5 given the trends. The MRGL risk expands westward into the Southern High Plains on D4. Kleebauer ..Previous Discussion.. Stronger flow will initially remain along the northern tier of the CONUS through mid-week with mean upper-ridging across the western to central U.S. Embedded shortwaves rounding the upper-ridge will eventually lead to deepening troughing across the the Midwest and adjacent areas by Thursday. The southward shift of stronger flow aloft will bring increasingly widespread storm chances from the central Plains east through the Mississippi Valley into the Ohio/Tennessee Valleys and central Appalachians. Seasonably high instability and moisture pooling along a southward progressing, wavy cold front will lead to multiple rounds of heavy rain- producing storms later this week and into the weekend. Mean flow generally parallel to the east-west oriented front will support clustering/training storms increasing the threat for longer- duration rainfall and higher totals. The embedded waves will help to slow the frontal progression at times also helping to increase the chance for repeated rounds/training of storms. For Friday (day 4), the latest guidance shows widespread areal average rainfall of 1-2" with good overlap between the ensemble means and AI guidance favoring the Ohio/Tennessee Valleys into the central Appalachians, where a Slight Risk has been maintained. While the guidance is not quite as bullish on amounts yet on Saturday (day 5), a similar set up will support additional locally heavy rainfall, with the concern being that much of the mean/AI guidance overlaps similar regions to Friday, favoring the middle to upper Ohio/Tennessee Valleys into the central Appalachians. Given the increasingly wet antecedent conditions expected from the prior days with additional storms likely, another Slight Risk has been introduced. Putnam ...Southwest U.S... Monsoonal activity will finally make an appearance by the end of the week with the threat ramping up into some more appreciable in regards to magnitude and coverage across the terrain of southeastern and central AZ, mainly following the Huachucas up through the Mogollon Rim in east-central AZ. PWATs will surge north along prevailing southerly flow on the western side of the broad upper ridge centered over the Four Corners. QPF signatures are textbook in monsoonal convection billowing up across the terrain at lead which is a good indicator of at least the isolated threat of flash flooding to kick off the Monsoon season across the Southwest. A MRGL risk has been added to account for the threat on D5 with perhaps an upgrade plausible on D4, but signals are not as prolific on Friday compared to Saturday on both the global deterministic and their ensembles. Kleebauer 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 $$