FOUS30 KWBC 310757 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 357 AM EDT Tue Mar 31 2026 Day 1 Valid 12Z Tue Mar 31 2026 - 12Z Wed Apr 01 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS WESTERN NEW YORK AND SOUTHEAST MICHIGAN... Overall upper pattern will become slowly backed as a deep longwave trough out west begins to pump the mid-level ridge downstream from the Mississippi River to the eastern CONUS. At the surface, a quasi-stationary front will bisect areas west to east from the Midwest the Northeast with a weak surface low migrating along the frontal positioning. Shortwave associated with the area of low pressure will eject through the Great Lakes leading to a period of convective development downstream into Michigan and points east. This initial round is expected to occur early in the period, producing moderate to locally heavy amounts across southeast Michigan and to the favored downwind locations of Lake Erie. The extra enhancement from Lake Erie should boost rainfall closer to 2 inches. As the morning progresses, the low will migrate into Ontario and the frontal boundary will drop southward toward the Ohio Valley. A second shortwave is set to eject and usher in another round of convection for the northern Missouri Valley. PW values will be increasing which should boost rainfall rates to 1-1.5 inches/hour. These two rounds of heavy rain for western New York areas downwind of Lake Erie will see widespread totals of 1.5-3" leading to a more elevated flash flood concerns, especially when combined with river flood concerns as stream flows across the region have been elevated since the previous events over the area. Flood Watches will be in effect for portions of western NY given the signal of both the river and flash flood threat aligning well with a targeted SLGT risk across the area. The Slight Risk extends back into Detroit due to the urbanization factors and expected heavy rainfall the front half the period into the metro which creates a better opportunity for flash flooding considering the setup. A Marginal Risk encompasses the northeastern portion of Illinois through southern Michigan, northern Indiana/Ohio, and extends well east and northeast to include Upstate New York, Northern New England, and the northern Hudson Valley as combination rainfall and snow melt will allow for elevated stream flows and any locally heavy rainfall could induce flash flood prospects. Campbell/Kleebauer Day 2 Valid 12Z Wed Apr 01 2026 - 12Z Thu Apr 02 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL STRETCHING FROM EASTERN KANSAS INTO SOUTHEAST IOWA... The latest guidance continued to trend westward with the overall QPF footprint however maintained consensus for the heaviest amounts to focus from eastern Kansas to the Missouri/Iowa border. A long axis of convection is expected from Texas into the Mid/Upper Mississippi Valley. A prominent warm-sector will materialize from west- central Texas into Missouri with a surface low forecast to be positioned over the Central Plains by Wednesday afternoon. Several shortwaves will eject northeast within and ahead of the mean trough leading to multiple waves of rainfall across parts of Kansas into Missouri. Multiple waves of heavier rain could impact the area. Despite the antecedent dry conditions in place, prolonged rainfall within the urban corridor with slower cell motions could lead to a greater threat for scattered flash flooding before the system finally moves eastward and the area sees the frontal passage. Areal averages of 1.5-2.5 inches are forecast however there is potential for isolated higher amounts of 3+ inches. A Marginal Risk area spans from central Texas to the Illinois/Indiana border. A Slight Risk area was hoisted for eastern Kansas, western/northern Missouri and southeast Iowa. Campbell/Kleebauer Day 3 Valid 12Z Thu Apr 02 2026 - 12Z Fri Apr 03 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF ILLINOIS, WISCONSIN AND LOWER MICHIGAN... By this period the surface low pressure/frontal system will stretch from the Mid-Atlantic back into the Ohio and Mid-Mississippi Valleys. Models have trended further north with the overall precipitation shield, now covering much of the Upper Great Lakes/Upper Midwest region. The moisture and instability along with the upper-level support could lead to flooding concerns across parts of the Great Lakes region. Colder air filtering across the northern tier will allow for wintry weather concerns in the Great Lakes to Interior Northeast thus limiting the area where flash flooding may occur/cause impacts. A swath of potentially impactful freezing rain/ice along with multiple inches of April snow, with the heaviest snow currently forecast in the U.P. of Michigan into northern Maine. Some areas could see transitioning precipitation types throughout the event. A Marginal Risk area is in effect for portions of southern Wisconsin, Lower Michigan and northern Illinois. 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