Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jul 07 2025 00:34:14 FOUS30 KWBC 070034 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 834 PM EDT Sun Jul 6 2025 Day 1 Valid 01Z Mon Jul 07 2025 - 12Z Mon Jul 07 2025 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF TEXAS, NORTH CAROLINA, & VIRGINIA... ....Carolinas/Southern Virginia... Tropical Depression Chantal continues to push north across NC and is expected to recurve northeast across southeast VA by morning.=20 The HREF, RRFS, and GFS guidance keeps the system convective into=20 the morning now...it may exit the East Coast as a tropical=20 depression at this rate. This should continue to result in a stripe of higher rainfall totals, with hourly amounts to 3" and local=20 totals to 6". Moderate Risk impacts across urban centers cannot be=20 ruled out given the rain expected. ....South-Central Texas... Afternoon and evening convection has waned, but both the 18z HREF=20 and 12z RRFS show a convective uptick towards 12z. Given the=20 sensitivity of this area and the upticks in total forecast rainfall from the ensemble of high resolution guidance, maintained the risk levels and shifted the areas back south to around Kerrville, which remains sensitive due to previous days of rainfall. Model guidance each day keeps extending the risk forward another day. Hourly=20 amounts to 3" with additional local totals to 6" remain possible. ....Marginal Risks Elsewhere... Marginal Risk areas were merged across the central Plains and=20 Midwest, where a heavy rain threat continues into the overnight hours. Added a Marginal Risk area across the Florida Big Bend/northwest FL Peninsula and dropped the Louisiana Marginal Risk. Areas were pared back based on radar reflectivity trends and 18z HREF/12z RRFS guidance. Hourly rain amounts to 2.5" with local amounts to 5" remain possible in isolated spots within the Marginal Risk areas. Roth Day 2 Valid 12Z Mon Jul 07 2025 - 12Z Tue Jul 08 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE UPPER MIDWEST TO THE SOUTHWEST, THE NORTHEAST TO THE SOUTHERN PLAINS, AND THE MID-ATLANTIC... ....2030Z Update... The Marginal Risk across portions of the Northeast/Mid-Atlantic was merged with the inherited Marginal along the coastal Mid-Atlantic with this update. Abundant tropical moisture associated with the remnants of Chantal will continue streaming north on Monday. While organized convection will likely have dissipated by Monday afternoon, the combination of ample heating and instability and that moisture should allow for widespread convective development, albeit disorganized, across the Mid-Atlantic. The disorganized nature of it should preclude any more than isolated instances of flash flooding, however the abundant moisture will favor any cells that form to have the potential of causing locally heavy rain and resultant flooding. The signal for drier conditions into southeastern and eastern Pennsylvania has largely disappeared, so the Marginals were merged. No other changes were made to the Marginal Risks in the middle of the country and from Texas through the Ohio Valley. The rainfall forecast in portions of central Texas around and southeast of San Angelo has increased a bit, associated with the same disturbance that has been causing the rain over the past few days. With each consecutive day the available moisture, instability, and advection in this area decreases...so we should continue to see the drying trend as regards coverage and intensity of convection to continue. A Slight Risk was considered in this area, but that will be tied to how much convection occurs this afternoon in the area, which for now has been muted, precluding an upgrade with this update. Wegman ....Previous Discussion... ....Eastern North Carolina to Eastern Pennsylvania and New Jersey... Although the surface circulation may no longer be well-defined, the mid level remnants and an its associated plume of deeper moisture are expected to lift north from eastern North Carolina along the Mid-Atlantic Coast ahead of an upstream trough, bringing the potential for locally heavy rain and perhaps some isolated flooding concerns from eastern North Carolina to eastern Pennsylvania and New Jersey. ....Northeast to Mid Mississippi Valley/Ozarks... A frontal boundary will continue to slide farther east across the Northeast this period. Deep moisture ahead of the boundary (PWs 1.75-2 inches and 2-3 std dev above normal), along with favorable upper jet forcing are expected to contribute to some organized heavier amounts from western and northern New York into parts of northern New England. Less organized activity is expected farther southeast. However, once again locally heavy amounts and isolated flooding concerns cannot be ruled out for areas back through the Ohio Valley into the mid Mississippi Valley and Ozark region. ....Southern Plains... The latest HREF shows that activity developing over parts of Texas on Day 1 may continue into Day 2, producing additional heavy amounts and prolonging flooding concerns across parts of Texas including portions of South-Central Texas and the Hill Country northeastward through North Texas... ....Upper Midwest to the Southwest... Amplifying southerly low level winds over the Plains will support increasing moisture across the central into the northern Plains. This moisture along with mid level energy moving out into the region, will support widespread showers and thunderstorms, with the guidance showing a signal for organized activity developing over the central High Plains. Forecast confidence is limited by significant model spread in the details. However, the potential for at least isolated flash flooding concerns cannot be ruled out. Farther to the south, activity again is expected to be less organized. But again, cannot rule out at least an isolated flash flooding concern, especially across vulnerable portions of eastern and central New Mexico. Pereira Day 3 Valid 12Z Tue Jul 08 2025 - 12Z Wed Jul 09 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE MIDWEST AND THE NORTHEAST TO THE OZARKS... ....2030Z Update... The guidance has dried out portions of Oklahoma, Texas, and New Mexico with the latest suite. Thus, due to lack of signal, the Marginal Risk was trimmed out of these areas, with the westernmost extent of the Marginal now in eastern Kansas and Oklahoma. The rainfall forecast has increased a bit across the Mid-Atlantic, particularly in the DMV area. Should these signals persist or increase, a Slight Risk upgrade may be needed with future updates, but given the newness up this update with little forcing noted, have opted to keep the area in a Marginal risk to allow for run- to-run consistency in the guidance. Wegman ....Previous Discussion... ....Northeast through the Ohio Valley... A cold front will continue to slide slowly southeast across the Northeast and the Mid Atlantic. Deepening moisture ahead of the boundary (increasing above 2 inches in many locations) will raise the potential for at least locally heavy amounts and isolated flooding to occur. ....Midwest to the Southern High Plains/Rockies... An upper level shortwave and associated axis of deeper moisture may produce storms with locally heavy amounts from the mid Mississippi Valley/Great Lakes region back through the mid Mississippi and lower Missouri valleys into the southern Plains. Meanwhile, low level upslope flow may produce another round of showers and storms developing along the southern Rockies into the High Plains. Pereira Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4HVFwCv7OcjZEzmshGIe-OfKNDMb9HqscOA3kx0uLWLN= SuIG-oBucxetB0Q1KAi0ICP9-L8HbMPLQx1deieogh9l8SI$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4HVFwCv7OcjZEzmshGIe-OfKNDMb9HqscOA3kx0uLWLN= SuIG-oBucxetB0Q1KAi0ICP9-L8HbMPLQx1deieof-cYLUs$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4HVFwCv7OcjZEzmshGIe-OfKNDMb9HqscOA3kx0uLWLN= SuIG-oBucxetB0Q1KAi0ICP9-L8HbMPLQx1deieo6S0xAcg$=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .