Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Jul 09 2025 15:22:18 AWUS01 KWNH 091521 FFGMPD PAZ000-MDZ000-VAZ000-NCZ000-WVZ000-OHZ000-TNZ000-KYZ000-092120- Mesoscale Precipitation Discussion 0627 NWS Weather Prediction Center College Park MD 1120 AM EDT Wed Jul 09 2025 Areas affected...Upper OH Valley...Central Appalachians/Blue Ridge Concerning...Heavy rainfall...Flash flooding likely Valid 091520Z - 092120Z SUMMARY...Developing showers and thunderstorms will be expanding in coverage going through the afternoon hours. High rainfall rates are expected to drive a likelihood for at least scattered areas of flash flooding. DISCUSSION...The late-morning GOES-E satellite imagery shows an elongated shortwave trough gradually transiting the OH Valley which will be interacting with a moist and increasingly unstable airmass pooled across the region, and this will set the stage for developing and expanding clusters of heavy showers and thunderstorms going through the early to mid-afternoon hours. Already the latest radar imagery shows a few small-scale clusters of showers and thunderstorms developing over eastern KY, southeast OH and central WV. MLCAPE values have already increased to 1000 to 1500 J/kg with the aid of morning solar insolation, and PWs of 1.5 to 1.75+ are in place which are about 1.5 to 2 standard deviations above normal. Some gradually increasing mid-level west-southwesterly flow will promote some uptick in shear parameters over the next several hours with effective bulk shear rising to about 25 to 35+ kts. These environmental trends should be conducive for seeing bands of multi-cell convection which will tend to be expanding in coverage with the aid of differential heating boundaries and orographics, with cell-motions gradually off to the east that will include far eastern KY, southeast OH, and much of WV initially. By mid-afternoon, this activity should then advance or develop across adjacent areas of the MD/WV Panhandles, western VA and also northwest NC involving the Blue Ridge and portions of the Mid-Atlantic Piedmont. The anomalous PW environment alone will favor high rainfall rates that may reach as high as 1 to 2 inches/hour which is strongly favored by the 12Z HREF guidance, but there will potentially be some orographic/terrain-induced forcing that may elevate these rates a bit further. This will especially be the case by mid-afternoon for areas over the central Appalachians and adjacent areas of the Blue Ridge involving MD/WV/VA. The 12Z HREF and 06Z REFS guidance collectively suggest some rainfall total potential by late-afternoon of 2 to 4+ inches. These rainfall amounts are likely to result in at least scattered areas of flash flooding. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!99ZAMRbadncOExsCxUOv9BBPH2KEQfOO6_ZA2Tn1ofAU_Igklhc--o8wfW6u5pSeXe2p= Eb7BDcvzUmWhuEL6B9yK7-I$ for graphic product... ATTN...WFO...AKQ...CTP...GSP...ILN...JKL...LWX...MRX...PBZ... RAH...RLX...RNK... ATTN...RFC...ALR...ORN...RHA...TIR...NWC... LAT...LON 39927742 39767683 38867716 37537862 36607948=20 35728092 35488223 35658290 36288278 36728273=20 37718283 38878310 39578238 39778093 39757863=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) .