FOUS30 KWBC 050817 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 417 AM EDT Fri Jun 5 2026 Day 1 Valid 12Z Fri Jun 05 2026 - 12Z Sat Jun 06 2026 ...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL ACROSS PORTIONS OF EASTERN NEBRASKA/KANSAS INTO THE MID-MISSISSIPPI VALLEY AS WELL AS MUCH OF TEXAS/SOUTHERN OKLAHOMA... ...Eastern Nebraska/Kansas to Mid-MS Valley... A northern stream shortwave with multiple embedded vort maxes will move through the Midwest Friday and provide lift for convection. First, convection and potential for flash flooding looks to be ongoing as the period begins 12Z Friday morning generally near the Iowa/Missouri and Iowa/Illinois border. This also sends precipitation into Wisconsin and Lower Michigan in the morning to early afternoon, but ahead of the influx of instability, so this is a more Marginal flood threat. The next and likely stronger energy in the shortwave, along with a cold front slowly shifting southward, will help develop another round of storms beginning in the afternoon and likely becoming enhanced in the evening and overnight hours. The HREF and its members as well as the REFS show this should be centered in southeastern Nebraska and northeastern Kansas to southern Iowa, with periods of QPF exceeding FFG (HREF and REFS probabilities 20-50% for FFG exceedance). A Slight Risk remains reasonable for this activity, but upgrades are not out of the question if training looks to overlap with the currently ongoing (Thursday night) convection. ...Texas to Southern Oklahoma... A compact southern stream upper low is forecast to drift from northern Mexico across Texas during the Day 1 period. This lifting mechanism will be paired with precipitable water anomalies in the 90-95th percentile in the southern Plains. There is some uncertainty in magnitude of instability due to cloud cover, but models show CAPE being sufficient at generally 1000-3000 J/kg, with the low aloft helping steepen lapse rates. Scattered convection that has the ingredients for flash flooding is likely to occur, so went with an upgrade to a broad Slight Risk in this issuance. The exact focus for the heaviest rain remains somewhat elusive, but there is some signal in the CAMs for east-central Texas. Also included areas to the west in the Slight, to include some of the typically more sensitive/lower FFG areas in the Hill Country to Concho Valley and Permian Basin. The Marginal Risk stretches back into New Mexico where there are some sensitive areas like burn scars. ...Central Gulf Coast... A disturbance likely in the form of a trough at low levels is forecast to drift slowly toward the central Gulf Coast, specifically southeastern Louisiana and southern Mississippi. With moisture anomalies over the 90th if not the 95th percentile and sufficient instability, intense rain rates could lead to a flooding threat in the form of a Marginal Risk. Though typically not a very sensitive area to flash flooding, antecedent wet conditions could enhance the potential. The back end of the trough could also lead to heavy rain in the Florida Keys, with the HREF and REFS neighborhood probabilities of reaching over 5 inches of rain greater than 60 percent, but considering the possibility the heaviest rain could be offshore and how much rain the Keys can handle with the sandy soils, held off on any risk area. Tate Day 2 Valid 12Z Sat Jun 06 2026 - 12Z Sun Jun 07 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE SOUTHERN PLAINS TO MISSISSIPPI VALLEY... ...Southern Plains/Mississippi Valley... The meteorological setup on Saturday across the south-central U.S. will be similar to Friday, through with the compact upper low gradually tracking north across the southern half of the Plains. The continued enhanced moisture and instability will yield an environment favorable for convection with intense rain rates causing flash flooding concerns. Areas farther north into Oklahoma should see stronger forcing, while the low level jet could be maximized farther south into Texas. Thus covered all this area with a Slight Risk. REFS probabilities (which extend through the Day 2 period) show scattered instances of QPF potentially exceeding FFG. Smaller scale boundaries leftover from thunderstorms on previous days could provide areas of focus that would likely be unclear before the near term. ...Central Gulf Coast... By Saturday the surface/low level trough mentioned in the Day 1 discussion should reach the central Gulf Coast during the day, and produce heavier QPF on land compared to Friday. Once again, antecedent conditions in the region are not typically sensitive, but are wetter than normal. REFS probabilities of exceeding FFG are 20-40% in southeast Louisiana, so will continue to monitor if slow storms/training are likely to cause more Slight Risk level impacts and need an upgrade. ...Ohio Valley... The northern stream shortwave is forecast to push through the Great Lakes/Ohio Valley and Northeast on Saturday, with a frontal system ahead of it. The front should lay west to east across the Ohio Valley, so scattered storms could train and cause isolated flash flooding. The Northeast can also expect some convection, but likely progressive enough to limit flash flood potential to below a Marginal. In this ERO issuance, connected the Plains and Ohio Valley Marginal Risks together. There is some potential for storms back into northern Missouri and vicinity, which could be very wet after multiple rounds of convection, so wanted to cover that area. Tate Day 3 Valid 12Z Sun Jun 07 2026 - 12Z Mon Jun 08 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE SOUTHERN/CENTRAL PLAINS TO LOWER/MIDDLE MISSISSIPPI VALLEY... Into Sunday, southern stream energy will continue to push north through the central/northern Plains and Midwest while opening up into a trough. This will once again provide forcing for thunderstorms in the Plains and Mississippi Valley. A low level jet of 30-40 kt should bring instability and moisture into the region. The best overlap of ingredients for flash flooding, supported by GEFS/ECens probabilities for over an inch of rain, will likely be centered over Missouri south into Arkansas and west into eastern parts of Kansas and Oklahoma, so this is where the Slight Risk is drawn for Day 3. Some convection could linger farther south toward the Gulf Coast, which the Marginal covers. By Sunday night, a northern stream trough with a strong vort max is forecast to push into the northern High Plains, bringing enhanced QPF ahead of it for a Marginal Risk stretching through portions of the Dakotas and western Minnesota. Tate 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