FOUS30 KWBC 111553 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1153 AM EDT Sat Apr 11 2026 Day 1 Valid 16Z Sat Apr 11 2026 - 12Z Sun Apr 12 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE SOUTHERN PLAINS... ...Central Plains... The MCS responsible for periods of excessive rainfall and resulting flash flooding will continue through the remainder of this morning. The 12Z TOP sounding shows as much as 1,000 J/kg of MUCAPE, along with a saturated and nearly 8,000ft warm cloud layer aloft, plus a highly sheared environment featuring excellent low- level SRH in the sfc-1km layer that exceeds 250 m2/s2. The ARW has handled this complex the best, and its new 12Z run suggests organized thunderstorms will linger for at least a couple more hours over northeast KS and far northwest MO. WPC has issued a new MPD, #0091, to highlight the ongoing flash flood threat. But with several more hours of excessive rainfall expected, opted to maintain the Marginal Risk until at least the 01Z update. Mullinax ...Southern Plains... Flash flooding is very much a concern from the Big Bend on north and east through the heart of TX this evening and into tonight. NAEFS shows anomalous IVT values over 500 kg/m/s (above the 97.5 climatological percentile) ahead of an approaching 200-500mb mean trough axis. Current visible satellite paints a generally broken cloud field over much of the state, although some surface based heating should allow for up to 1,000 J/kg of MLCAPE late afternoon and this evening. Storms initiating along the dryline will have a favorable vertical wind profile that sports sufficient shear (30-40kts of sfc-6km shear) and sfc-3km storm-realtive helicity (SRH) >100 m2/s2. Any discrete cells initially should manifest into a congealed cluster with some cells potentially training and back-building north of the Rio Grande. The new 12Z HREF shows pockets of moderate-to-high chances (50-80%) for rainfall totals >3" from the Rio Grande to as far north as the Red River. More concerningly, there are moderate chances (40-50%) for localized totals >5" close to Del Rio, TX. While a moderate was considered, ultimately held a Slight given the regions lower FFGs. However, this is more of a "high-end" Slight, given the potential for rainfall rates up to 2"/hr and the typical flash flood risks that the TX Hill Country has a long history of enduring. Mullinax ---Previous Discussion--- The presence of an increasing southerly low level will transport Gulf moisture northward and pool over the Plains and Mississippi Valley as an upper level trough enters the West and ridging builds over the East. Meanwhile the upper dynamics and embedded shortwave energy will support ascent ahead of a longwave trough. At the surface, a dry line across West Texas will help serve as an initiating mechanism for convection in the afternoon. Strong to severe thunderstorms are expected to fire up over the Southern and Central High Plains, migrating eastward eventually making headway into the adjacent Concho Valley and lower Trans Pecos. As cells merge due to cold pool mergers and low-level jet initiation, a large cluster of heavy rainfall will ensue through the rest of Saturday night into Sunday morning. General consensus maintains 2-4 inches possible from the Concho Valley in West Texas to the Red River Valley in southern Oklahoma. Neighborhood 24 hr QPF HREF probabilities show a strong signal for 50-80% for 2 inches for this region and 40-70% for 3 inches. A Slight Risk for Excessive Rainfall remains in effect across portions of the Southern Plains, especially the areas referenced above. Campbell ...Upper Midwest and Great Lakes... The Marginal Risk was expanded southward into southern WI, northeast IA, and northern IL for the 16Z update. Latest ARW and HRRR have trended south with their QPF axis with storms forming closer to the lifting warming front. This setup has eerily similar characteristics that led to the flash flooding in northeast KS this morning; sheared lobes of 500mb vorticity to the west of the upper-level ridge axis with area-averaged soundings showing notable low-level SRH values and over 500 J/kg of MUCAPE aloft. Warm cloud layers at least 8,000ft deep and NAEFS highlighting a robust 750 kg/m/s IVT over central IA being aimed at southern WI tonight also supported both warm rain processes and healthy moisture advection. 1-hr FFGs remain as low as 1" in some locations given the saturated soils in place. With these factors accounted for, the Marginal Risk will focus on the potential for flash flooding in these aforementioned areas tonight and into the early morning hours on Sunday. Mullinax ---Previous Discussion--- Scattered to widespread convection is expected across parts of Wisconsin and Michigan as moisture increase along a warm front lifting northward through the region. Areal averages of around 1 inch are still on track. Much of the region will be sensitive to additional precipitation as there has been ongoing snow melt and high river flows. Although it may be isolated, flash flooding may be possible during this period. A Flood Watch remains in effect across the Michigan U.P. and far northern Lower Michigan and Wisconsin. Campbell Day 2 Valid 12Z Sun Apr 12 2026 - 12Z Mon Apr 13 2026 ...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR CENTRAL TEXAS... ...Central Texas... Multiple rounds of strong to severe storms will persist across the Southern/Central Plains and Lower Mississippi Valley given high moisture presence, favorable wind shear and instability in place. A meandering dry line across the region will provide a focus for backbuilding cells. With limited eastward progression of the QPF footprint expected during this period, there is a growing threat for flash flood concerns across portions of Hill Country to the I-35 corridor south of Dallas. A Slight Risk for Excessive Rainfall is now in effect for central Texas for the threat with a Marginal Risk extending northeastward through Oklahoma and adjacent areas of Kansas/Missouri/Arkansas. ...Northern Michigan... Gulf moisture will continue to transport northward and interact with the frontal boundary draped across the region. An additional 1 to 2 inches of rain is expected across the upper portion of the Mitten which may expedite local snow melt and runoff. A Marginal Risk for Excessive Rainfall remains in effect across northern Michigan. Campbell/Wilder Day 3 Valid 12Z Mon Apr 13 2026 - 12Z Tue Apr 14 2026 ...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF THE UPPER MISSISSIPPI VALLEY AND UPPER GREAT LAKES REGION... Showers and thunderstorms will persist through this period as the warm front lifts into southern Canadian and the cold front advances through the Northern Plains into the Upper Mississippi Valley. Additional rainfall will maintained an elevated threat for isolated flash flooding and speed up snow melt around the region. A Marginal Risk remains in effect from eastern Minnesota to northern Michigan. 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