Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat May 10 2025 22:22:12 AWUS01 KWNH 102221 FFGMPD GAZ000-110420- Mesoscale Precipitation Discussion 0251 NWS Weather Prediction Center College Park MD 620 PM EDT Sat May 10 2025 Areas affected...Central GA Concerning...Heavy rainfall...Flash flooding possible Valid 102220Z - 110420Z SUMMARY...Slow-moving supercellular MCS cluster over central GA may result in sufficiently high enough rainfall rates for some isolated flash flooding concerns this evening. DISCUSSION...A long-lived supercellular MCS cluster moving gradually through central GA continues to remain very well-organized and has been tending to gradually track a tad to the right over the last few hours as it begins to interact with a warm front draped west to east across the region. Much of the convection is aligned with a rather strong instability gradient with as much as 1500 J/kg of MLCAPE pooled along the front. Meanwhile, there is favorable shear in place with 0-3 km effective bulk shear values of 30 to 40 kts which is playing a role in maintaining the supercell character of the convective mass. PWs across the region are quite moist with values of as much as 1.6 to 1.7 inches and this is running a solid 1.5 to 2 standard deviations above normal. Rainfall rates are impressively high with dual-pol radar showing hourly rainfall totals reaching 1.5 to 2.5 inches. The slow cell-motions overall with this activity are yielding heavier 3-hour totals that have been on the order of 3 to 4+ inches based on MRMS data. Over the next few hours, the HRRR and RRFS guidance suggest a continuation of well-organized clusters of strong convection impacting areas of central GA with high rainfall rates that are likely to still reach 1.5 to 2.5 inches/hour. The HRRR guidance this evening in particular shows some back-building cells around the southwest flanks of the convection in association with a persistently moist southerly low-level jet of 30 to 40 kts, and this may help drive small-scale focused areas of heavier rainfall amounts that may reach 5+ inches. The 18Z HREF and 12Z REFS ensemble suites both suggest at least low-end probabilities (20% to 30%) of seeing the 3-hour FFG values exceeded going through 03Z/11 PM EDT. Therefore, at least an isolated threat for flash flooding is expected to exist this evening across central GA, with the more urbanized locations at greatest risk for impacts. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4EXeqx2txJ9LjwExBFkX8L-ph7QLv6NombxP22FJV4jHUoQAHF591i3PpAhrj2JnJ681= kqqYG-RYeI9OQXYdnAoCeM0$ for graphic product... ATTN...WFO...CAE...CHS...FFC...TAE... ATTN...RFC...SERFC...NWC... LAT...LON 33608236 33228194 32548200 31958269 31748353=20 31718430 32268464 33188397 33578319=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) .