806 FOUS30 KWBC 092025 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 425 PM EDT Thu Apr 9 2026 Day 1 Valid 16Z 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... 16z Update: The forecast remains on track for a Marginal Risk for Excessive Rainfall as modest moisture return from the south and an increase in instability through the day will interact with a stationary front aligned from northern Kansas eastward to Illinois. A dual QPF maxima of 1-2 inches is forecast along and to the north of a front across the I80 corridor from Iowa to northern Illinois. Northeast Kansas into Missouri will be another focal point for possible heavier rainfall rates near and south of the front and QPF totals nearing 1-3 inches. ..Previous Discussion.. 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... 16z Update: Thunderstorms this morning were moving across the Space Coast, the Treasure Coast, and the Miami metro. Radar analysis showed rainfall rates of an inch to two inches per hour over saturated soils from previous days. Showers and storms will continue amid the strong northeasterly flow along the east coast of Florid and the Marginal Risk continues this afternoon. ..Previous Discussion.. 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. ...South-Central Texas... A sub-Marginal Risk for Excessive Rainfall is possible from the Hill Country westward to the Rio Grande. The QPF forecast calls for a general 1.0-2.0 inches across the region today as enough moisture and instability will be present for scattered thunderstorms. A disturbance moving across the Mexican Plateau could enhance locally heavier rainfall totals across the Rio Grande, with some uncertainty if the storms can maintain across the U.S./Mexico border late this afternoon into the evening. Dry antecedent conditions and low signals from the HREF neighborhood probabilities exceeding 2 inches precludes a Marginal Risk for Excessive Rainfall as of this forecast package. Oravec/Wilder 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... 20z Update: The Marginal Risk for Excessive Rainfall had a minor shift south into northern Oklahoma based on latest CAM consensus. The Marginal Risk was extended farther south into northern Oklahoma, including the Tulsa metro, as models show a southward trend of the maximum QPF where the front aligns. The west to east front stretching from the Central Plains into the Mid-Mississippi Valley today will begin to push southward early tomorrow. This front will then meander across the Central Plains, east into the Lower MO Valley and Mid- Mississippi Valley. PWAT 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. HREF neighborhood probabilities show 40-70% for 2 inches and 20-40 % for 3 inches of rainfall across these areas. Wilder/Oravec Day 3 Valid 12Z Sat Apr 11 2026 - 12Z Sun Apr 12 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE SOUTHERN PLAINS... 20z Update: Upgraded to a Slight Risk across West Texas into the Red River Valley. An axis of above average PWATS is expected to move across the Southern and Central Plains on Saturday. Upper dynamics will support ascent ahead of a longwave trough entering the West Coast, as well as a shortwave trough traversing the High Plains. As ridging builds in across the east, this will also promote strong southerly flow and a low level jet over the Southern Plains and Texas to advect moisture and instability in the area. At the surface, a dry line across West Texas will help serve as an initiating mechanism for convection. The QPF footprint in the afternoon cycle has a signal for 2-4 inches possible from the Concho Valley in West Texas to the Red River Valley in southern Oklahoma. Rainfall rates could also be as high as an inch or two per hour with organized convection likely as noted with SPC's Slight Risk across the region. A Slight Risk for Excessive Rainfall was introduced from West Texas to the Red River Valley on Saturday for the potential of scattered flash flooding. Wilder/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