FOUS30 KWBC 090823 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 423 AM EDT Thu Apr 9 2026 Day 1 Valid 12Z Thu Apr 09 2026 - 12Z Fri Apr 10 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PARTS OF THE CENTRAL PLAINS, LOWER MISSOURI AND MID-MISSISSIPPI VALLEYS AND ALONG THE EAST COAST OF FLORIDA... ...Central Plains to Mid-Mississippi Valley... The surface frontal boundary stretching from the Central Plains into the Mid Mississippi Valley is expected to be nearly stationary day 1, remaining oriented in a general west to east direction. In the wake of the strong height falls moving northeast from the Upper Lakes into southeast Canada, additional shortwave energy expected to dive southeast from the Northern Plains into the Upper MS Valley. These height falls will help strengthen the low level south southwesterly flow into this boundary, push PW values to 1 to 2+ standard deviations above the mean and enhance uvvs in the above average PW axis in the vicinity of the stationary front. This will support increasing convection late Thursday afternoon into the early hours of Friday in the vicinity of this boundary with locally heavy rainfall totals and isolated runoff issues. Only some minor changes made to the previous marginal risk area, trimming it to the northwest across northern IL, and extending it slightly farther south into northeast KS to match the latest model qpf consensus. The marginal risk fits well with where the latest HREF neighborhood probabilities are highest for 1 and 2"+ totals during the upcoming day 1 period. ...East coast of Florida... The strong low level east northeasterly flow will continue for at least the beginning of the day 1 period along the east coast of Florida. PW values will remain above average during the day on Thursday, before beginning to decrease as the low level onshore flow weakens after 0000 UTC Friday. There will continue to be the threat of locally heavy rains from slow moving to nearly stationary rain bands in this strong moist onshore flow region. Confidence is not great with placement, leading to little in the way of changes with to the previous broad marginal risk area along the east central to southeast Florida coastal region, with the greatest risk of runoff issues in more urbanized regions. Oravec Day 2 Valid 12Z Fri Apr 10 2026 - 12Z Sat Apr 11 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE CENTRAL TO SOUTHERN PLAINS... The west to east front stretching from the Central Plains into the Mid-Mississippi Valley day 1 will begin to push southward late day 1 into early day 2. This front will then again becoming stationary during the day on Friday, oriented west to east from the Central Plains, east into the Lower MO Valley and Mid-Mississippi Valley. Similar to the day 1 period, PW values should increase in the vicinity of this front in response to strengthening southerly low level inflow. Shortwave energy pushing northeastward into this high PW axis in the vicinity of this front will support areas of slow moving convection along this front, locally heavy rains and isolated runoff issues. The previous marginal risk area was pushed southward by approximately 50-75 miles to fit the latest model qpf consensus. There still is some latitudinal spread with the max qpf axis, with the more southern solution favored in the latest WPC qpf. Oravec Day 3 Valid 12Z Sat Apr 11 2026 - 12Z Sun Apr 12 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE SOUTHERN PLAINS... An axis of much above average PW values expected to increase in size day 3 across the Southern to Central Plains, into the Upper MS Valley in a region of strengthening south southwesterly to southwesterly low to mid level flow. There is the likelihood of numerous shortwaves moving northeastward in this mid level southwesterly flow across the mid section of the nation, supporting increasing precip chances/coverage across this region. There still is a large spread in the models with respect to placement of max qpf, leading to low confidence at the moment for the day 3 time period. Given the model spread and dry antecedent soil moisture and high FFG values, the risk area was maintained at marginal, with the potential for upgrade to slight in subsequent model cycles if better agreement with max qpf axes occurs. Oravec 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