Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jul 21 2025 00:06:59 AWUS01 KWNH 210006 FFGMPD KYZ000-INZ000-ILZ000-MOZ000-IAZ000-210605- Mesoscale Precipitation Discussion 0768 NWS Weather Prediction Center College Park MD 805 PM EDT Sun Jul 20 2025 Areas affected...North-Central to Northeast MO...Central IL...Southern IN Concerning...Heavy rainfall...Flash flooding likely Valid 210005Z - 210605Z SUMMARY...Heavy showers and thunderstorms will be developing and expanding in coverage going through the evening hours. High rainfall rates and some cell-training concerns are expected to drive an increasing threat of flash flooding. DISCUSSION...The late-afternoon GOES-E IR satellite imagery shows a few convective clusters beginning to organize and grow upscale across portions of central IL through southern IN. The convection is initiating along a well-defined surface trough/outflow boundary where there is a substantial pool of moisture and instability. MLCAPE values along and just south of the boundary are as high as 2000 to 3000+ J/kg from eastern MO through southern IN, with PWs across the region of 2.0 to 2.25 inches. The environment is also somewhat sheared with as much as 20 to 30 kts of effective bulk shear in place. Some weak mid-level vort energy is also aligned in a west to east fashion across the region from earlier convective activity. Going through the evening hours, a gradual increase in convection is expected as additional upstream vort energy arrives and couples with increasingly convergent low-level flow near this outflow boundary. A nearby front just to the north will also be aiding in the overall convergent low-level flow regime, and this will be supported by some increase in right-entrance region upper jet dynamics by late this evening. In the near-term the convection should tend to be more focused over central IL and southern IN, but gradual development is expected farther west across areas of north-central to northeast MO and into west-central IL by later this evening. Concerns will tend to grow in time for there being multiple clusters/bands of heavy showers and thunderstorms that will be capable of training over the same area. Rainfall rates are expected to be very high given the thermodynamic environment and relatively organized nature of the thunderstorms. Some rates may reach 2 to 3 inches/hour, with rainfall totals by 06Z (1AM CDT) of as much as 3 to 5 inches possible which is supported by some of the 18Z HREF and 12Z REFS guidance. These rains are likely to produce areas of flash flooding, and some potential for locally significant urban flash flooding may grow in time, and especially after this period as additional heavy rainfall threatens the area. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_JP5qB4-Yao_jMQJanPKMZOXDKyJ8BRhML7L1bcAuXweTAEZxyg8vpadAnVVVjqPC5f5= _CkBvGwzoLPPa5j60UEwIhk$ for graphic product... ATTN...WFO...DVN...EAX...ILN...ILX...IND...LMK...LSX...PAH... ATTN...RFC...KRF...MSR...TIR...NWC... LAT...LON 40559143 40418990 40178850 39788678 39148507=20 38308519 38088675 38098837 38379036 38979313=20 39489405 40219407 40509293=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) .