Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jul 23 2024 18:02:46 AWUS01 KWNH 231802 FFGMPD MDZ000-VAZ000-NCZ000-WVZ000-SCZ000-TNZ000-KYZ000-240000- Mesoscale Precipitation Discussion 0708 NWS Weather Prediction Center College Park MD 201 PM EDT Tue Jul 23 2024 Areas affected...Southern Mid-Atlantic into portions of the Appalachians Concerning...Heavy rainfall...Flash flooding likely Valid 231800Z - 240000Z SUMMARY...Isolated to scattered instances of flash flooding will be likely this afternoon and into at least the early evening hours as showers and thunderstorms with very heavy rainfall rates develop and expand in coverage. DISCUSSION...The early afternoon GOES-E visible satellite imagery shows an expanding CU/TCU field across much of central and southern VA down through a large chunk of central and northern NC. Strong diurnal heating continues across this region, and this coupled with a moisture-rich boundary layer is already fostering MLCAPE values of 1500 to 2500 J/kg. Over the next several hours, showers and thunderstorms will be developing and expanding in coverage, and the activity especially across areas of south-central to southeast VA and possibly north-central NC may become locally focused given a corridor of stronger low-level convergence coinciding with greater boundary layer instability. The region more broadly is also under some influence of weak right-entrance region upper-level jet dynamics which will tend to favor at least some weak deeper layer ascent. Areas farther west across western NC, southwest VA and southeast WV will also be in an environment conducive for scattered convection with the aid of differential heating boundaries and related nearby orographics associated with the higher terrain of the Appalachians and especially the Blue Ridge. Already, the latest radar imagery shows convective initiation underway across these areas. Given PWs that are on the order of 1.75 to 2 inches from the Piedmont eastward into the coastal plain (and more regionally running as much as 2 standard deviations above normal), the convection that evolves this afternoon and early this evening will be capable of producing rainfall rates reaching up to 2.5 inches/hour. Relatively slow cell-motions coupled with eventually a threat for some cell-mergers may allow for some storm totals by early this evening to reach upwards of 2 to 4 inches with some spotty 5+ inch amounts possible. The 12Z HREF guidance favors areas of north-central NC and especially south-central to southeast VA including the Hampton Roads vicinity seeing the heaviest rainfall potential. Given the rainfall potential and overall moist to locally wet antecedent conditions, isolated to scattered instances of flash flooding are generally likely. Urban flash flooding may become a notable concern again for the I-64 urban corridor from Richmond on down through the Norfolk/VA Beach vicinity. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7UWNzePVSy2f1vXxIErV2EJ43X5HN8nx0UnHsejBHPnbBjCRvosW60kIsWACIpWZ_LFP= 8XltrDEgrpmeKPf5CnC-_dc$ for graphic product... ATTN...WFO...AKQ...CAE...GSP...ILM...JKL...LWX...MHX...MRX... RAH...RLX...RNK... ATTN...RFC...LMRFC...MARFC...OHRFC...SERFC...NWC... LAT...LON 38708014 38707858 38257726 38117602 37667540=20 36917549 35807615 35047732 34767942 35238203=20 36148279 37348240 38218147=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) .