Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Aug 30 2023 21:03:32 AWUS01 KWNH 302103 FFGMPD NCZ000-SCZ000-GAZ000-310300- Mesoscale Precipitation Discussion 1012 NWS Weather Prediction Center College Park MD 502 PM EDT Wed Aug 30 2023 Areas affected...east-central GA...south-central SC...southern NC Concerning...Heavy rainfall...Flash flooding likely Valid 302100Z - 310300Z Summary...Tropical Storm Idalia to continue to cause numerous flash floods with additional localized totals of 3-6" expected. Some significant and life threatening flash flooding is also expected. Discussion...Idalia is now a tropical storm, as the core of strong winds steadily weakens as it treks farther inland across GA/SC. The heavy rainfall in association with Idalia, on the other hand, continues to be prolific with a large swath of 3-5" totals (and locally higher) occurring to the west and north of the center of circulation (from landfall over the Big Bend of FL north-northeastward through south-central GA). Numerous flash floods have occurred along this path of heavy rainfall, and the flooding is far from over with this system as this core of very efficient tropical rainfall (with 1-3"/hr rates) continues to track northeastward into the Carolinas. Out ahead of this heavy rainfall core, very strong low-level moisture transport is facilitating efficient rainfall banding off the Atlantic/Gulf Stream with streaks of 1-2"/hr rainfall rates (resulting in 1-3" totals before the arrival of the heavy rainfall core). The mesoscale environment is otherwise characterized by ML CAPE of 100-1000 J/kg, PWATs of 2.4-2.8" (near record levels in CHS/MHX sounding climatology), and 35-45 kts of deep layer (0-6 km) shear. In addition, the right-entrance region of a ~120 kt jet streak over the Mid-Atlantic/Northeast continues to provide additional synoptic uplift for convection. The combination of leading bands of heavy rainfall and the concentrated core of tropical moisture near Idalia's center is expected to result in a swath of (additional) 3-6" localized totals from east-central GA through south-central SC and southern NC through 03z. The 12z HREF and more recent HRRR runs remain in good agreement regarding this scenario, and much of this expected rainfall may fall in as little as 3 hours. Corresponding flash flood guidance (FFG) is near 3.0", suggesting that numerous flash floods are likely to continue (with the corridor for highest likelihood of realizing 3-6" totals occurring mostly between the areas of greatest population density, with the exception of Wilmington). Some of these flash floods may be significant and life threatening, particularly if near 6" totals can be realized in more vulnerable, poor drainage metropolitan areas. Churchill ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6LrgB11amaYUMOkPSTi55OpqrCeki0lsQsDb4wZLt4WJ1SgBywDzc3lQAEsxUQmY8zhq= RdNvaRZQdei0ME7RmqwWK4Q$ for graphic product... ATTN...WFO...CAE...CHS...FFC...GSP...ILM...MHX...RAH... ATTN...RFC...SERFC...NWC... LAT...LON 35357717 35017622 34007715 33387796 32258035=20 32228153 32398245 33528243 34428133 35128000=20 35327871 35337800=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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .