549 FOUS30 KWBC 160011 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 811 PM EDT Wed Apr 15 2026 Day 1 Valid 01Z Thu Apr 16 2026 - 12Z Thu Apr 16 2026 ...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR THE GREAT LAKES/NORTHERN OHIO VALLEY AND IN/NEAR THE OZARKS.. ...Great Lakes and Ohio Valley... Another round of convection developed developed this afternoon over portions of Wisconsin and Iowa where moisture and instability pooled ahead of frontal boundary. As the line of storms continues to move eastward...there will certainly be overlap with areas that were impacted by multiple days of moderate to heavy rainfall. Antecedent conditions favor a more sensitive soil moisture composition along with remnant elevated streamflows situated across the area from eastern Iowa through northern Illinois and southern Wisconsin. The area of lower Michigan remained the most sensitive region. Precipitable water anomalies in the 95th to 99th percentile range for this seasonal climatology. ...Ozarks and adjacent areas... One change in the area was to introduce a Slight Risk area in/near the Ozarks for this evening into the overnight hours. Dewpoints in the lower 70s were located immediately upstream while a dryline was approaching from the west at the same time. Localized training/repeating convection is likely to result in spots of 1 to 2 inch rainfall rates at times, Given the terrain...think the combination is enough to warrant a Slight Risk. Father north...maintained a Marginal risk area where antecedent conditions remained pretty dry with the 1/3/6 hr FFG parameters all sufficiently above 2.5" for each threshold. That said, urbanized areas will still see higher run off capabilities with a potential for localized flash flooding in the evening and overnight time frame. ...Northeast... Little change made to the previous outlook with a widespread MRGL risk extending from western New York into portions of Pennsylvania and into parts of southern New England. HREF neighborhood probabilities are fairly robust for >1" (50-80%) across much of the above corridor with the highest probs for both >1" and >2" located downwind of Lake Erie. Urbanized zones will be the primary areas of concern here. Bann Day 2 Valid 12Z Thu Apr 16 2026 - 12Z Fri Apr 17 2026 The probability of rainfall exceeding flash flooding guidance is less than 5 percent. Campbell/Kleebauer Day 3 Valid 12Z Fri Apr 17 2026 - 12Z Sat Apr 18 2026 ...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF THE MID-MISSISSIPPI VALLEY INTO THE CENTRAL PLAINS... 20Z Update: A deep, positively-tilted longwave trough will wander eastward out of the Rockies on Friday leading to broad large scale ascent from the Southern Plains to the Midwest. A well-defined axis of diffluence ahead of the mean trough with several shortwaves ripping through the flow will enhance an area of convective development within a strengthening warm-sector environment positioned between a strong cold front over the High Plains and a quickly advancing warm front migrating poleward through the adjacent Mississippi and Ohio Valley's. The current setup is conducive for a large heavy rain footprint with ensemble mean QPF already denoting an expansive 1-2" output with embedded higher totals. This is even prior to the CAMs additions that handle the magnitude of convection better, so anticipating some 3+ inch means likely to materialize in future updates. The main trend this period is the continuation of the ML outputs being further south and southwest with the QPF core as the primary theta_E ridge correlates well with the heaviest precip as convective magnitudes will likely be maximized within that deeper moist, unstable environment. Global deterministic is already beginning to show signs of leaning in that direction with the 12z ECMWF the most notable in the southern alignment of the heavier QPF footprint. This actually matches the ECAIFS, to a degree in its presentation, another favored overlap that tends to verify well once we reach inside 72 hrs from an event. In this case, the main area of interest will likely be a little further south and southwest compared to what was forecast previously in regards to the SLGT risk. That said, there's still hints the overall meridional pattern involved could still enhance heavier precipitation further north into the Midwest where the previous SLGT risk was aligned. As a result of the trends and some continuity, decided to expand upon the SLGT risk further south with the highest confidence in heavy precip likely lying within the Missouri Valley down into perhaps eastern KS as the upper jet presentation would likely promote the best the LER dynamics over that particular corridor. This is a period to monitor closely as the expanse of heavier precip will likely produce scattered flash flood prospects given the environmental favorability, as well as the lower FFG's in place across northern MO down into eastern KS. Any further south push would put OK in play as well, so this forecast could be a bit fluid pending the continued trends. Kleebauer 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