Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Sep 26 2024 06:52:48 AWUS01 KWNH 260652 FFGMPD VAZ000-NCZ000-SCZ000-GAZ000-TNZ000-261045- Mesoscale Precipitation Discussion 1062 NWS Weather Prediction Center College Park MD 252 AM EDT Thu Sep 26 2024 Areas affected...central/northern GA into the southern to central Appalachians Concerning...Heavy rainfall...Flash flooding likely Valid 260651Z - 261045Z SUMMARY...Areas of heavy rain with south to north training to build northward through GA into the southern and central Appalachians through the morning. Rainfall rates of 1-2 in/hr will be likely, but isolated 2+ in/hr cannot be ruled out. DISCUSSION...Regional radar imagery across the Southeast at 0630Z showed a "Y" shaped appearance in reflectivity with a branch of heavier rainfall extending northeastward from the FL Panhandle into central GA, co-located with a remnant outflow/effective frontal boundary. A second axis of higher reflectivity extended northwestward across the GA coast into central GA and a broken axis of higher reflectivity values was located from central GA into western NC. These axes of higher reflectivity/heavier rainfall aligned fairly well with the leading edge of low level (0-3 km AGL) moisture flux where a plume of 2+ inch precipitable water values was building northward across GA via southeasterly low level winds of 20-30 kt. Mesoscale areas of rotation were embedded within the precipitation shield, associated with enhanced convergence and higher reflectivity along with with south to north training following the deeper layer steering flow. Short term RAP forecasts showed an axis of low level moisture flux convergence focusing from central GA into the southern Appalachians through 11Z along with gradually strengthening 925-850 mb winds as Hurricane Helene continues to advance north from the southern Gulf of Mexico, increasing the low level height gradient across the Southeast. Flow is expected to be especially focused along the northern GA/SA border with RAP forecasts of 40 kt by 12Z. The increased low level flow into and perpendicular to the axis of terrain, coupled with lift within the right entrance region of a 110-120 kt jet max aloft, should allow for steady/periods of heavy rain with rainfall rates of 1-2 in/hr. The flash flood threat will also exist farther north toward the upslope regions of the central Appalachians into western NC and southwestern VA where heavy rain has already fallen over the past 1-2 days, although reduced instability/moisture with northern extent may temper rainfall rates compared to those farther south. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_mf8Di26G500TgTbBXssuA17EmMKPTbty_iVZuLEhVaiDzKYKRNhX8wlFaPb9Hk6zscb= hHKQLgLumB83leSZcQ8gS-g$ for graphic product... ATTN...WFO...CAE...CHS...FFC...GSP...MRX...RNK... ATTN...RFC...LMRFC...OHRFC...SERFC...NWC... LAT...LON 36958081 36798069 36308087 35898114 35198192=20 34738225 34178229 32608194 32398331 32648457=20 33238469 34088456 34588434 35168392 35948323=20 36168293 36418229 36588189 36758143 36938111=20 =20=20=20=20=20=20=20=20=20=20=20=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) .