FOUS30 KWBC 031553 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1153 AM EDT Fri Jul 3 2026 Day 1 Valid 16Z 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... 16Z Update: Heavy rainfall this morning way over-performed in areas centered over Central IA within proximity of a surface trough analyzed overhead. The setup across the Plains remains a bit complex with the passage of multiple shortwaves and the undulation of formidable theta_E/instability maxima being advected into the region on the lead of a broad trough to the west. Models continue to struggle in this setup which is customary with more weakly forced environments dominating the synoptic and mesoscale convective scheme. The trend the past several days has been for heavier precip to shift south of where guidance is suggesting, and this is likely trending in that direction just based on observational tendencies the past 24 hrs. This would also correlate well with the ML outputs remaining a solid 50-100 miles south in their depictions of where the heaviest precip is forecast (albeit still missing the mark on magnitude by a considerable margin). Considering the upstream shortwave propagation into Central High Plains today, carrying eastward through the period and beyond, the forecast is likely to be correct in cell initiation across central and eastern NE later this afternoon, however the thought process is the cold pool maturation generated by any convection will likely propagate further southeast with the target of heaviest rainfall likely to be centered across the Missouri River basin and surrounds encompassing southeastern NE down through southwestern IA, northwest MO, and northeast KS. This is actually addressed in a few of the CAMs, but still not a great consensus at the moment as models are struggling even at initialization this morning with ongoing convection. The SLGT risk was adjusted south to account for historical trends and expectation for cells to migrate further southeast after initiation later this evening. Heavy precipitation over Central IA at any point is liable to cause problems given the antecedent top layer soils fully saturated with flooding ongoing in some areas to the north of Des Moines where 5+ inches have fallen since the overnight time frame. 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. This pattern remains steadfast in guidance with persistence in the flow over the area as the western Lakes area remains far enough removed from the greater mid and upper forcing evolution over the Central High Plains. A MRGL risk was also expanded over more of southwestern SD due to a complex upper pattern that materialized over the area this morning. The current setup calls for training/back-building convection over the area near Rapid City for at least another 2-4 hours before activity can finally begin to vacate the area. More on this setup and the drivers of the local pattern can be reviewed in the latest MPD #0575 issued for the region. Kleebauer ...Southeast Florida... 16Z Update: Little to no change to the previous MRGL risk placement as convection billowing up along the sea breeze with western cell motions could spur an isolated flash flood threat in any urbanized settings in southeast FL. HREF probs continue to depict modest 20-40% probabilities for local amounts greater than 5" with a higher confidence (60-80%) for greater than 3" over the same area. Highest confidence in more appreciable totals continues to be over central FL to the west of Lake Okeechobee, but those areas tend to be much harder to flood considering very high FFG's bordering 4-5" per hour necessary. Low probs for >3" per hour allowed a continued nil in that area, but a non-zero chance is forecast given the heavy rain anticipated. Will monitor for any adjustments necessary as activity occurs. Kleebauer ..Previous Discussion.. 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 $$