888 FOUS30 KWBC 030804 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 404 AM EDT Fri Jul 3 2026 Day 1 Valid 12Z Fri Jul 03 2026 - 12Z Sat Jul 04 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF IOWA AND EASTERN NEBRASKA... ...Northern/Central Plains to the Midwest... A quasi-stationary frontal boundary remains draped through the Upper Midwest under faster mean flow rounding the eastern upper- ridge. Embedded upper- wave(s) will help to encourage storm development with daytime heating. Seasonably high moisture (PWATs 1.5-2") and instability (ML CAPE 3000-4000 J/KG) will also continue to support robust storms capable of heavy downpours with now- available hi-res guidance supporting locally heavy totals of 3-5". Heavy rainfall for portions of central and eastern Iowa expected early Friday from a dying MCS. A renewed MCS will develop by Friday evening across eastern Nebraska and will track eastward through southern Iowa. This southward track will give northern parts of Iowa a reprieve from the multi-day heavy rainfall. Significant localized flash flooding could occur from eastern Nebraska and southern Iowa due to much heavier hourly rainfall rates. A Slight Risk area cover from eastern Nebraska to the Iowa/Wisconsin/Illinois borders. Showers and storms will develop east from there through the Chicago metro and along Michigan's southern border through the day, but short residence times of the heavy rainfall due to sufficiently fast movement of the storms should keep any flash flooding risk in these areas isolated and consistent with a Marginal Risk. ...Southeast Florida... Afternoon convection expected to develop/increase across the middle of the state south of Lake Okeechobee, then slowly drifting east towards the urban corridor from West Palm Beach south, where any isolated flash flooding threat exists. A small Marginal Risk area was maintained. Putnam/Campbell Day 2 Valid 12Z Sat Jul 04 2026 - 12Z Sun Jul 05 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL STRETCHING FROM THE NORTHERN/CENTRAL PLAINS THROUGH THE MIDWEST, OHIO AND TENNESSEE VALLEYS, AND MID-ATLANTIC... With the upper ridge weakening, there will be at least an isolated threat for excessive rainfall and flash flooding potential from the Plains to the Mid-Atlantic region for this period. High moisture and instability will remain in place along the northern side of the ridge ,south of the frontal boundary, with at least scattered thunderstorms likely with the daytime heating. The potential for greater coverage of heavier rainfall, higher totals, and more scattered instances of flash flooding is greatest over the Northern/Central Plains into the Upper Midwest where embedded upper-wave(s) will help to encourage more widespread thunderstorms and the possibility of more organized convective systems. Uncertainty remains on where the highest concentration of heavy rainfall will materialize, hence the broad area with a Marginal Risk for flash flooding. However, another MCS will likely materialize along the Nebraska/Northeast Kansas/Northwestern Missouri corridor Saturday night/overnight and will be progressive in nature. Putnam/Campbell Day 3 Valid 12Z Sun Jul 05 2026 - 12Z Mon Jul 06 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE MID-ATLANTIC... The pattern setting up during this period is favorable for heavy rainfall, especially near the Appalachians and locations east toward the Eastern Shore. A low to mid level trough interacting with a backdoor front should provide a focus for heavy rainfall and at least moderate levels of instability should overlap with PWs over 2" across portions of the region. There will also be the potential for training and backbuilding of convection as westerly flow aligns with the boundary. A Slight Risk area covers most of Pennsylvania, Maryland, northern Virginia, and portions of Delaware and New Jersey. A broad Marginal Risk area spans from eastern Oklahoma eastward to the Mid-Atlantic/southern portions of the Northeast. Campbell Day 4 and Day 5 Valid 12Z Mon Jul 06 2026 - 12Z Wed Jul 08 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE MID-ATLANTIC ON MONDAY... The heavy rainfall potential along the wavy front over the Mid- Atlantic will carry over from the Day 3 period into the Day 4 period. A Slight Risk area is in effect for much of the same locations over northern Virginia, Maryland, northern Delaware, New Jersey and eastern 2/3 of Pennsylvania. A Marginal Risk area spans from Mississippi northeastward to the Mid-Atlantic coast and northward into Upstate New York and southern New England. Campbell 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 $$