FOUS30 KWBC 050810 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 410 AM EDT Sun Jul 5 2026 Day 1 Valid 12Z Sun Jul 05 2026 - 12Z Mon Jul 06 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST KANSAS INTO OKLAHOMA AND PORTIONS OF INDIANA AND OHIO... A MCV is expected to continue its eastward progression into/across Ohio maintaining an elevated threat for localized flash flood along its path. A bit further downstream scattered to widespread heavy rainfall will be focusing along the wavy, east-west orientated frontal boundary draped over southern portions of the Northeast. Back building/training of slow moving storms capable of hourly rates rates greater than 2 inches/hour will track across eastern Pennsylvania and New Jersey. Guidance is signaling areal averages of 3 to 6 inches with local maximums of 8+ possible along this corridor. The latest guidance maintains focus of the highest probabilities for the intense rain rates and higher QPF over central to eastern PA, portions of central to northern NJ, and far northern Maryland. The combination of some terrain areas and the highly urbanized corridor makes this area much more vulnerable to flash flooding. While there remains some spatial uncertainty to exactly where the greatest rainfall will occur, the setup favors some locally significant flash flooding will be possible. The Slight Risk spans from northeast Indiana to the Mid-Atlantic Coast with an embedded Moderate Risk area over eastern Pennsylvania and north/central New Jersey. A broad Marginal Risk area spans from eastern Oklahoma/Kansas eastward to the Mid- Atlantic/southern portions of the Northeast. Campbell ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE MID-ATLANTIC/NORTHEAST... The threat for excessive rainfall and scattered areas of flash flooding will remain for portion of the Mid-Atlantic for this period. Rainfall occurring during the Day 1 and Day 2 periods may lead to increased soil saturation and lowered flash flood guidance for this region, thus making it more sensitive for additional heavy rainfall. Near and just south of this front instability of 2000 J/kg or greater and PWs over 2" are forecast, an environment supporting efficient rainfall and high hourly rates. The inherited Slight Risk area was adjusted to reflect the latest trends and WPC QPF placement. As follows, the southern boundary of the Slight was extended south toward the Virginia and North Carolina border to capture locations were hi-res guidance is suggesting localized 3+ inches, particularly along I-95 and adjacent urban areas. Stronger low level convergence will be capable of producing a broader area of moderate to locally heavy rainfall across New York into southern New England. However a limiting factor will be reduced availability of instability-- rainfall rates will likely not peak as high as those further south. Thus, this area is covered by a broad Marginal Risk from portions of Upstate New York to the Cape, south to the Carolinas and then southwest into Arkansas and northern Louisiana. ...Montana... Isolated instances of heavy rainfall will be possible capable of producing localized flash flooding possible for areas ahead of and along an approaching front. A shortwave trough rounding the base of the building southwestern ridge will trigger convection. A Marginal Risk was maintained as well as expanded to the west/southwest to cover mover of central/western parts of the state. Campbell Day 3 Valid 12Z Tue Jul 07 2026 - 12Z Wed Jul 08 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE NORTHERN PLAINS TO UPPER GREAT LAKES... ...Northern Plains to Upper Great Lakes... A seasonably moist, unstable airmass will be in place along the northern side of an upper-ridge building over the western to central U.S. early next week. An upper-level wave rounding the ridge will help trigger scattered to widespread thunderstorm development at the leading edge of the deeper moisture over the northern High Plains. Propagation ahead of a developing surface wave along a quasi-stationary frontal boundary and developing low- level jet will help maintain storms into the overnight hours through the northern Plains with the potential for at least organized clusters of storms if not a mesoscale convective system. Good consensus amongst the deterministic model guidance on areal average totals in the 1-2" range and locally higher amounts of 3-4" supports the threat for scattered flash flooding. A Slight Risk is in effect for portions of the Dakotas and into west/central Minnesota. A Marginal Risk area spans from eastern Montana, most of the Dakotas and Minnesota, far northwest Iowa and northwest Wisconsin. ...Mid-Atlantic to Carolinas... Persistent troughing over the region along adequate instability and PW values around 2 inches will keep convection across the area for this period. Isolated to scattered convection capable of heavy rainfall rates will maintain a Marginal Risk for excessive rainfall in place for this period. Putnam/Campbell Day 4 and Day 5 Valid 12Z Wed Jul 08 2026 - 12Z Fri Jul 10 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE UPPER GREAT LAKES WEDNESDAY... A seasonably moist, unstable airmass will be in place along the northern side of an upper-ridge building over the western to central U.S. early next week. An upper-level wave rounding the top of the ridge will help trigger scattered to widespread thunderstorm development along a frontal boundary through the northern Plains/Upper Midwest Tuesday with ongoing/additional storms spreading into the Upper Great Lakes Wednesday. Storms will likely focus ahead of an eastward moving surface wave along the boundary with clustering/upscale growth potentially leading to a more organized system. Typical uncertainty on the exact location and coverage of convective development remains a concern particularly as the storm evolution Tuesday will likely impact storm development/evolution Wednesday. However, there remains good consensus amongst the deterministic model guidance on areal average rainfall totals in the 1-2" range, locally 3"+, supporting the threat for scattered flash flooding. A Slight Risk of Excessive rainfall is in place from east-central MN into northern WI and the UP/northern LP MI, with the potential for areal adjustment of the risk in subsequent outlooks. The embedded shortwave energy will help to subtly deepen/expand troughing more broadly across the the Midwest and adjacent areas on Thursday. The southward shift of stronger upper-flow aloft into the central Plains east through the Middle Mississippi/Ohio Valleys and Lower Great Lakes will bring more scattered thunderstorm chances across the region. Seasonably high instability and moisture pooling along a southward progressing cold front will support locally heavy rainfall bringing the threat for at least isolated instances of flash flooding, and a broad Marginal Risk of Excessive Rainfall has been outlined. A targeted Slight Risk may eventually be necessary with more confidence in the frontal position as storm motions may tend to run generally parallel to the boundary helping to lead to prolonged/repeated rounds of rainfall. Putnam 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 $$