518 FOUS30 KWBC 021549 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1149 AM EDT Thu Apr 2 2026 Day 1 Valid 16Z Thu Apr 02 2026 - 12Z Fri Apr 03 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF NORTHERN ILLINOIS, WISCONSIN AND MICHIGAN... 16Z Update: The overall setup and expected evolution remains consistent from previous forecasts with the heaviest rainfall expected to occur after 18z from eastern IA to points east and northeast as the surface low slowly intensifies and carries north- east from IA through southern WI. Warm front positioning this morning showed a modest advancement north, verifying well with the current CAMs output as the boundary begins pushing through northern IL at this hour. Expectation is for a defined warm sector to materialize across eastern IA, northern IL, and southern WI with the northern periphery of the theta_E ridge centered between the Wisconsin Dells to just south of Sheboygan. Any area south of this delineation will be under a threat of scattered convection capable of heavy rainfall with rates generally between 0.5-1"/hr with the max likely capped between 1-1.5"/hr given the instability/moisture depth present. Despite climatological anomalies of PWATs around 3 standard deviations above normal, this is still modest in the context of more appreciable rainfall prospects since it's still only the beginning of April. The primary areas of focus will be those more urbanized zones where run off potential is highest just due to the limited absorption that can occur within the infrastructure. Milwaukee, northern Chicago suburbs, and Madison are the prime targets when assessing the 12z HREF neighborhood probs for >2" as percentages are running between 40-70% from just north of the Quad Cities to the northern suburbs of Milwaukee. HREF EAS is very aggressive for at least 1" in that same broad area, however there is a precipitous drop off in the >2" EAS meaning the maximum is likely capped considering the short term training risk and then steady northeast progression as the region experiences the cold front passage later this evening. Considering the above variables, the only changes made were an adjustment further southwest with the risk into eastern IA to account for some trends in CAMs showing more aggressive convective development later this afternoon over this particular zone which upped some of the neighborhood probabilities for totals reach 2". The best chance remains across southern WI with the Milwaukee metro the most likely location for FFG exceedance and flash flood prospects. Kleebauer Day 2 Valid 12Z Fri Apr 03 2026 - 12Z Sat Apr 04 2026 ...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF THE SOUTHERN PLAINS INTO THE OZARKS REGION... Strong to severe thunderstorms along with embedded heavy rainfall will track across the Southern/Central Plains into the Mississippi Valley/Midwest during this period. Moisture (with PWs over the 90th, perhaps 95th percentile) and instability are likely to pool along and ahead of the associated cold front and produce widespread convection. Storms likely beginning in the afternoon are expected to get reinforced through the evening and night hours as a low level jet picks up ahead of the cold front. Given that some of this region has been drier, it will take awhile before there are substantial flash flood concerns. Some of the highest amounts/rates are likely to focus over parts of central and eastern Oklahoma down into the Red River Basin between the Texas and Oklahoma border. Consensus has areal averages of 1 to 3 inches while some of the hi-res guidance is hinting at isolated maximums of 4 to 7 inches. Slight Risk area spans from north-central Texas to southwest-southern Missouri. Campbell/Kleebauer Day 3 Valid 12Z Sat Apr 04 2026 - 12Z Sun Apr 05 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE CENTRAL AND EASTERN GREAT LAKES SOUTHWESTWARD TO CENTRAL TEXAS AND THE LOWER MISSISSIPPI RIVER VALLEY... Much of the convection that evolves across the Marginal Risk area on D3/Sat will depend on specific evolution of convective complexes that originate from the central/southern Plains on D2/Fri. Although those details are a bit uncertain at the time frame, general consensus is that one or two MCSs will traverse the Mississippi Valley/Mid-South early in the forecast period before convective redevelopment occurs upstream along a composite outflow/cold front during peak heating hours from central Texas to Mississippi. Areas of training are likely if this pattern holds, with initiating boundaries supporting deep convection eventually becoming more parallel to steering flow aloft. Portions of this region may require an upgrade to Slight in later outlook updates. Farther north, convective coverage is far less certain - particularly from Illinois to Ohio. Deeper convection south of these areas could disrupt inflow/instability and lead to a minimum in precipitation in these areas. Again - this regime is uncertain. The primary reason Marginal was maintained for D3 from Illinois eastward to New York State and West Virginia was soils/local sensitivity. Soils are wetter with eastern extent from prior rainfall and could still be sensitive to even moderate rainfall by D3/Sat in a few spots. Cook 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