Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jun 28 2025 19:41:59 AWUS01 KWNH 281941 FFGMPD PAZ000-MDZ000-WVZ000-OHZ000-KYZ000-INZ000-290130- Mesoscale Precipitation Discussion 0543 NWS Weather Prediction Center College Park MD 341 PM EDT Sat Jun 28 2025 Areas affected...Ohio Valley Concerning...Heavy rainfall...Flash flooding possible Valid 281940Z - 290130Z Summary...Showers and thunderstorms blossoming ahead of a cold front will expand and train through the afternoon and into the evening. Rainfall rates of 1-2"/hr are expected, which through training could produce 2-3" of rain. Flash flooding is possible. Discussion...The regional radar mosaic this afternoon shows a rapid uptick of convective coverage aligned SW to NE from eastern Indiana through southwest Pennsylvania. These storms are continuing to expand and intensify as reflected by the GOES-E day-cloud phase RGB, suggesting more numerous storms will develop during the next few hours. This convection is blossoming in response to convergence along an approaching cold front, which is impinging into robust thermodynamics characterized by PWs around 1.7 inches (above the 90th percentile at KILN according to the SPC sounding climatology) and SBCAPE over 3000 J/kg. Through the afternoon and into this evening, the cold front is likely to sag slowly south and east as modest 500mb height falls occur downstream of a shortwave moving into the Upper Midwest. This evolution combined with modest upper diffluence will help drive synoptic ascent atop the pronounced low-level convergence ahead of the front. This lift will move into an increasingly favorable environment as the 850mb inflow, while modest in speed (10-15 kts and veering) maintains a resupply of favorable thermodynamics as it originates from a pool of high PWs over 2 inches. The HRRR is under-forecasting the current activity, but the ARWs, NAMnest, and even the RRFS have a better handle on the ongoing coverage and are favored through the evening. This suggests that storms will continue to expand and build into the greater instability to the SW, and then train steadily to the east as weak Corfidi vectors and 0-6km mean winds become aligned to each other and the sagging front. Rain rates will likely reach 1-2"/hr (50-60% chance from the REFS) leading to short duration rainfall as much as 0.5-1.5 inches in 30 minutes, and this could quickly overwhelm soils leading to runoff. However, the greater concern is where training occurs, which should be prevalent along the front, as this could produce 2-3" of rain in some areas over a short period of time. If this training falls atop any urban areas, or across more sensitive soils due to terrain or FFG that is as low as 1.5"/3hrs from recent rainfall, instances of flash flooding would become more likely. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8nAQkQBFEPmn75sWybBmmLW7t2Es7pTBJnbpEXcrKt-EyjQ0gMBJVGVcKf4Cat3xwhEw= SClogB_jvOC_B__pauC6O_4$ for graphic product... ATTN...WFO...CLE...CTP...ILN...IND...JKL...LMK...LWX...PBZ... RLX... ATTN...RFC...RHA...TIR...NWC... LAT...LON 41017956 40737902 40127875 39187921 38577999=20 38298060 38228211 38548386 38868527 39188601=20 39458625 39778621 40138576 40198405 40418201=20 40738094 40918023=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) .