Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Aug 28 2024 04:39:42 AWUS01 KWNH 280438 FFGMPD INZ000-WIZ000-ILZ000-MOZ000-IAZ000-280935- Mesoscale Precipitation Discussion 0938 NWS Weather Prediction Center College Park MD 1238 AM EDT Wed Aug 28 2024 Areas affected...north-central IN/IL into adjacent portions of IA/MO/WI Concerning...Heavy rainfall...Flash flooding possible Valid 280435Z - 280935Z SUMMARY...Scattered to numerous thunderstorms across the Midwest may result in localized flash flooding from rainfall rates between 1 to 3 in/hr and spotty totals of 2-4 inches. DISCUSSION...04Z surface observations and radar imagery showed a southward propagating line of thunderstorms extending from eastern IL into northern IN. Additional thunderstorm activity was observed from eastern IA into northern IL, largely tracking toward the northeast. An elongated outflow boundary was analyzed south of the ongoing thunderstorms, extending from north-central IN into central IL/MO. The 00Z sounding from ILX was representative of the environment ahead of the cold front marking strong MLCAPE near 3500 J/kg and a wet bulb zero height at 13.6 kft. Since then, nocturnal cooling and colder surface-based temperatures due to rain-induced outflow have resulted in stabilization with respect to near surface based parcels. However, steep 700-500 mb lapse rates of at least 7 C/km (7.7 C/km on the ILX sounding) and very moist low levels are continuing to support pockets of elevated CAPE with values of 1500-3000 J/kg and little to no inhibition. While the area has been fairly dry over the past 7-10 days, rainfall rates of 1-2 inches in 30 minutes have been observed within the ongoing convection. Individual cell movement will be from the SW ow W, on the north side of a strong mid-level ridge, but outflow and cell mergers will impact overall system movement in a more chaotic manner. Southward extent of thunderstorms will be mitigated by anomalously warm 700 mb temperatures near +12C located near the OH River, acting to cap the environment. Lingering instability will likely maintain some degree of strong convection for at least another few hours with potential for 2 to 4 inches of rain in less than 2 hours. Overlap with urban areas or other locations with poor drainage may result in localized flash flooding. Trends will continue to be monitored overnight with any subsequent MPDs issued as needed. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6IEO8Q1pkI05o1SnD9uBgtvo1JoPE6SDZlaHiMdDs6fGh9nfPramZoUGtxBEZ10Aydig= 0MijE_Barx270DjTIPJnZh8$ for graphic product... ATTN...WFO...DMX...DVN...ILX...IND...IWX...LOT...LSX...MKX... ATTN...RFC...NCRFC...OHRFC...NWC... LAT...LON 42938785 42768730 42048731 41228659 41398551=20 41338495 40738499 40238562 39488703 39188862=20 39259049 39639150 40239207 40779223 41569177=20 42299000=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) .