Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jul 26 2025 00:47:31 FOUS30 KWBC 260046 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 846 PM EDT Fri Jul 25 2025 Day 1 Valid 01Z Sat Jul 26 2025 - 12Z Sat Jul 26 2025 ....THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR MUCH OF NORTHEAST KANSAS AND FAR NORTHWESTERN MISSOURI... ....01Z Update... Multiple upper level circulations/disturbances are tracking along a stalled out front from Kansas northeast to northern Illinois. A stationary line of storms across eastern Kansas may try to lift north and east across the Kansas City Metro. However, they will still be tied to the stationary front in the area, supporting training thunderstorms. The Moderate Risk was trimmed out of central Kansas, where cloud cover has cleared with little chance of development through the night as all convective activity builds northeastward with time. The Moderate Risk is primarily for urban areas such as Kansas City and St. Joseph, MO where the combination of urban areas and very heavy rainfall in areas that have recently seen heavy rains could quickly cause numerous instances of flash flooding into tonight. Further east along the front, convective activity is likely to be a bit more scattered, but will have equal availability of moisture and instability necessary to support storms capable of multiple=20 inch per hour rainfall rates. The storms into Illinois should be=20 somewhat more progressive in their northeastward movement along the front, such that despite some areas, such as Chicago, seeing very=20 heavy rainfall over the past 24 hours, the lesser amount of time=20 expected for any one area to be subject to heavy rainfall should=20 reduce the flooding potential down to the Slight category. A=20 consensus of the guidance highlights far northern Illinois and far=20 southern Wisconsin for the heaviest rains tonight, so the Slight=20 was nudged northward with this update. Marginals were trimmed significantly with this update. The Slight and Marginal Risks were trimmed out of portions of central Missouri, central Illinois, and central Indiana, as nearly all convective activity with the front should remain north of these areas. In the Northeast, the storms are lining up perpendicular to the=20 northwesterly flow, greatly limiting any flooding potential, so the Marginal Risk was trimmed with this update east of western=20 Pennsylvania/the Alleghenies. Much of the more concentrated rains along the Gulf Coast are from southern Mississippi west, so Alabama and the FL Panhandle were removed from the Marginal. Much of southern New Mexico was removed from the Special Marginal Risk as all storms have largely dissipated from this region. Active convection continues in northern New Mexico and Colorado, where the Marginal Risk remains. Wegman Day 2 Valid 12Z Sat Jul 26 2025 - 12Z Sun Jul 27 2025 ....THERE IS A SLIGHT RISK FOR PARTS OF PENNSYLVANIA AND THERE ARE=20 MARGINAL RISK AREAS FOR EXCESSIVE RAINFALL OVER MULTIPLE REGIONS OF THE COUNTRY ON SATURDAY... ....The Midwest to Mid-Atlantic region... Convection is expected to fire along the west-east oriented front and will persist given the ample moisture present. The continuous influx of high PW values over this boundary will aid in locally enhanced rainfall. The environment will be favorable for training and backbuilding of storms over recently wet soils. This will elevate the risk for localized flash flooding, especially for the flash prone areas within the terrain of Pennsylvania and surrounding locations. A Slight Risk was raised for this part of the country. Campbell ....Gulf Coast... The upper trough and associated surface low hugging the Gulf coast will remain situated across the western half of the Gulf with the main area of surface reflection likely coming ashore into TX during the period. Model solutions remain varied...but high precipitable water and enough mid- and upper level forcing to continue producing downpours across the central and western Gulf coast with an emphasis on the immediate coastal plain. ....Northern Plains... 21Z update... The Marginal Risk area was expanded further into north-central Minnesota to cover where some of the guidance saw an increase in the QPF footprint and locally higher amounts. Campbell The next in a series of potent shortwave will eject northeast out of the Northern High Plains resulting in another round of heavy precip potential with more organized convective clusters migrating through the Dakotas. Isolated 2 to 3 inch rainfall maxima are possible and embedded within broader areas of lesser rainfall amounts. The pattern is fairly progressive so see little reason to move from the Marginal risk category. ....Northeastern California and Northwest Nevada... Almost a carbon copy of the prior period for convective impacts lingering across the Northern Sierra up through northeastern CA and northwest OR. The upper pattern is pretty slow to breakdown with the diffluent area in the longwave setup still situated over northern CA into NV. Instability is expected to be modest and slightly above normal moisture in the terrain will offer the capability for some isolated flash flood concerns within any complex terrain and burn scar remnants in the above area. Bann Day 3 Valid 12Z Sun Jul 27 2025 - 12Z Mon Jul 28 2025 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF THE UPPER MIDWEST... ....The eastern Dakotas to northern Minnesota... Effects of a shortwave trough interacting with a surface front across the Upper Midwest will continue into Sunday as does uncertainty with placement and timing of any convection capable of supporting heavy rainfall. There are some signals in the GFS and ECMWF for possible MCS development while the NAM does generate some storms but would be less concerning, Given the amount of rainfall recently across parts of northern Minnesota...will maintain the Slight risk in deference by the GFS/ECMWF for the time being. ....The Mid Atlantic to southern New England... Mid-level flow flattens over the Great Lakes and Ohio Valley...allowing embedded shortwave energy to start digging east of there with corresponding height falls. The atmosphere will still be anomalously moist and capable of supporting convection with localized downpours that produce localized flooding. ....Southwest US... Deeper moisture that made its way across parts of the Gulf and inland across Mexico should start to be drawn northwest into parts of the Southwest United States...resulting in scattered late day and evening convection across parts of New Mexico and a small portion of Arizona. Bann Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4EgrMxU8v737yh-xTubFH63euFuOWQxNh2BPFxKezsLe= aqdvkjsCu6pY5SSMECS-zskoqhCNYzPxwBW3wmUIIBTdfi4$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4EgrMxU8v737yh-xTubFH63euFuOWQxNh2BPFxKezsLe= aqdvkjsCu6pY5SSMECS-zskoqhCNYzPxwBW3wmUIdPpOGSg$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4EgrMxU8v737yh-xTubFH63euFuOWQxNh2BPFxKezsLe= aqdvkjsCu6pY5SSMECS-zskoqhCNYzPxwBW3wmUImevd4c0$=20 =3D =3D =3D To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .