Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Aug 12 2025 12:09:51 AWUS01 KWNH 121209 FFGMPD NCZ000-SCZ000-GAZ000-121808- Mesoscale Precipitation Discussion 0918 NWS Weather Prediction Center College Park MD 808 AM EDT Tue Aug 12 2025 Areas affected...portions of central/Upstate South Carolina and central North Carolina Concerning...Heavy rainfall...Flash flooding possible Valid 121208Z - 121808Z Summary...Areas of heavier rainfall are materializing across the discussion area and 1 inch/hr rain rates are increasing in coverage. These rates are falling on sensitive ground conditions from prior rainfall. Flash flooding is possible this morning. Discussion...Over the past half hour, radar and satellite have indicated an uptick in convective intensity and coverage generally in areas from central South Carolina into southwestern North Carolina. This uptick in convective coverage appears to be tied to a weak mid-level shortwave trough/vorticity max over central South Carolina. The showers/storms are in a marginally unstable, but very moist environment (1.5-2 inch PW values, 1000 J/kg SBCAPE) with weak inhibition, fostering efficient rainfall rates with the ongoing activity. Latest MRMS data suggests that 1 inch/hr rain rates were beginning to materialize in a few spots.=20 Furthermore, these rates were falling on sensitive local ground conditions due to prior rainfall, with FFG thresholds below 0.25 inch/hr in a few spots across the discussion area. Models/observations are all suggestive of a gradual increase in both coverage and intensity of convection through the morning hours. With weak southwesterly steering flow in place, several areas of slow-moving convection and occasional cell mergers are expected to develop and boost rain rates into and above the 1 inch/hr threshold at times. These rates will pose a flash flood risk, though the greatest risk of impacts may occur near sensitive urban areas and locales that have experienced the highest rainfall totals over the past 1-2 days. Areas just west of Columbia, SC could experience excessive runoff in the near term, with additional locales (including urban areas near Raleigh/Durham and Columbia) experiencing an increasing threat through 16Z/noon EDT or so. Cook ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4EKeuxKsk7-uujb1RTjzVj24QTN_HxsiRRw3en8OGRvX76ScVdRYaokfSDnyrYKlMvi9= Lvb1fb0043lWWUYt3lj3bWE$ for graphic product... ATTN...WFO...CAE...GSP...ILM...MHX...RAH...RNK... ATTN...RFC...ALR...ORN...NWC... LAT...LON 36297879 35577734 33738053 33548204 35158286=20 35978159 36268043=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) .