Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Jul 23 2025 01:41:27 AWUS01 KWNH 230141 FFGMPD SCZ000-GAZ000-230600- Mesoscale Precipitation Discussion 0783 NWS Weather Prediction Center College Park MD 940 PM EDT Tue Jul 22 2025 Areas affected...Midlands of South Carolina through much of Georgia Concerning...Heavy rainfall...Flash flooding possible Valid 230139Z - 230600Z Summary...Thunderstorms developing ahead of a wave of low pressure will continue for several more hours as they drift southwest across Georgia. Rainfall rates of 2-3"/hr are likely at times, leading to 2-3" of rain with locally more than 4" possible. This may cause additional flash flooding. Discussion...The regional radar mosaic this evening shows an expansion of thunderstorms with heavy rain moving from the Midlands of South Carolina into central Georgia. This convection is blossoming in response to ascent being forced via a wave of low pressure moving inland from the Atlantic and drifting along a stationary front analyzed by WPC. 850mb inflow is being accelerated north of this wave as measured via local VWPs at CAE/LTX, reaching 20-25 kts, more than double the mean 0-6km winds which is additionally enhancing ascent. This accelerated moist inflow is also impinging into the stationary front, and with modest upper diffluence positioned aloft, forcing for ascent is maximized across Georgia this evening, helping to persist convective activity. Although SBCAPE has weakened due to loss of daylight, elevated instability within the residual layer remains impressive as analyzed by the SPC RAP MUCAPE of 3000 J/kg. This is overlapping exceptional PWs of 2.2 to 2.4 inches (measured at KJAX and KCHS, respectively, a record at KCHS) leading to still extreme thermodynamics across portions of the Southeast. The increased lift driven by the accelerated inflow (both into the mean wind and the stationary front) is helping to tap this MUCAPE to support intense rain rates which have been estimated via KFFC to be 2"/hr, leading to MRMS measured rainfall of more than 3" in the past hour in a few locations. The CAMs are struggling to handle the ongoing activity, and each successive run of the HRRR wants to squelch convection much too rapidly. This suggests that the HREF exceedance probabilities for 2"/hr rates of around 30% are likely under-done, and conceptually the environment should be able to support 2-3"/hr rates for a few more hours. As mean 0-6km winds remain 10 kts or less, and propagation vectors collapse to just 5 kts, locally enhanced short-term training through storm mergers/collisions are likely. Where this occurs, additional rainfall of 2-3" with locally more than 4" is possible thanks to these intense rainfall rates. Although there remains uncertainty in to how long this activity will persist, at least a few more hours of flash flood potential remains. This is despite soil moisture that is generally normal to below normal with respect to the 0-10cm layer according to NASA SPoRT. However, these intense rates will likely quickly overwhelm soils, especially in urban areas, or anywhere training can occur, which could lead to additional flash flooding into tonight. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_JRY6NzTd8gFzSuxTPhvrpxKNVvCXI6SSweL9cfMxAn01TBNg0Lki8DflWY3VLzCCwPK= wiw9CRtiWrEFdj-6gOEyjpg$ for graphic product... ATTN...WFO...CAE...CHS...FFC...GSP...JAX...TAE... ATTN...RFC...ALR...NWC... LAT...LON 34408214 34148129 33428118 32818162 32218202=20 31618250 31468309 31548379 32078444 32978467=20 33828460 34388414=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) .