866 FOUS30 KWBC 312359 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 759 PM EDT Tue Mar 31 2026 Day 1 Valid 01Z Wed Apr 01 2026 - 12Z Wed Apr 01 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL NEAR PORTIONS OF THE GREAT LAKES AND PARTS OF THE NORTHERN MID-ATLANTIC STATES... Moisture has been funneled in between a trough out West and a mid- level ridge downstream from the Mississippi River to the eastern CONUS. Various shortwaves rippling through the Westerlies have led to thunderstorm activity from the Southern Great Lakes/Midwest into NY. To the east...convection has been focused between an incoming front and a pre- frontal outflow boundary near the southern Great Lakes and southern NY. Convection appears to becoming more elevated across portions of southern NY ahead of an incoming convective wave due to an increase in CIN. A total of 2-4" of rain over the past day or so has made soils more sensitive across southern and central NY, so maintained the Slight Risk in those areas. Upstream/to the west, cells have at times aligned across far northeast IL, northern IN, into northwest OH where 1-3" of rain has occurred thus far, with other activity from southwest Lower MI attempting to add to the heavy rainfall as it dives into portions of northern IN over the next several hours. This is all occurring ahead of a shortwave currently extending from the Lower Peninsula of MI across northern IL. Due to ongoing convection and the possibility of more activity early Wednesday morning as additional shortwaves move in aloft, made alterations to the dimensions of the Slight Risk area across OH, IN, and IL, shifting it south somewhat and extending it farther west. The Marginal Risk was extended farther to the west- southwest due to a model signal of a convective uptick across southeast KS which moves across portions of MO. Given the ingredients available, hourly amounts up to 1.5" with additional local totals to 3" are possible from portions of the Midwest into the Northern Mid-Atlantic states and neighboring areas of New England into Wednesday morning. Roth Day 2 Valid 12Z Wed Apr 01 2026 - 12Z Thu Apr 02 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL STRETCHING FROM NORTHEAST KANSAS INTO IOWA... There continues to be a slight west/northward trend with both the surface low and overall QPF footprint as a system gets organized across the Plains during the Day 2 period. 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 from the south-central Plains into the Middle Mississippi Valley. There is increasing agreement for the heaviest QPF to be located from northeast Kansas into east-central Iowa, with some training potential, leading to 1-3 inch areal average amounts in this region, with some potential for isolated higher amounts of 3+ inches. A slight risk remains for this region, with a slight north and west shift in the placement consistent with latest trends, however the area has overall been dry recently which may limit flood/flash flood potential somewhat. Farther south, a long axis of convection is expected from Texas to Kansas along the cold front, but storms in this area should be more progressive and soils are even more dry than to the north. A marginal risk continues to be fine for this area. The marginal risk also extends eastward into the Ohio Valley to account for early period storms lingering along a stationary front draped across the region. Santorelli 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. 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 where precipitation is most likely to stay mostly/all rain. Santorelli/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