Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jun 08 2025 22:33:16 AWUS01 KWNH 082232 FFGMPD PAZ000-MDZ000-VAZ000-DCZ000-WVZ000-090400- Mesoscale Precipitation Discussion 0404 NWS Weather Prediction Center College Park MD 631 PM EDT Sun Jun 08 2025 Areas affected...southwestern PA into northern and eastern WV, northern VA, western MD, and DC Concerning...Heavy rainfall...Flash flooding likely Valid 082230Z - 090400Z Summary...Short term localized totals of 2-4" likely to lead to isolated to scattered instances of flash flooding. Discussion...Showers and thunderstorms have been increasing in coverage over the past few hours in the vicinity of a warm front draped from southwestern PA through western MD, the WV Panhandle, northern VA. A shortwave trough will pivot through the area over the next several hours, providing additional lift via DPVA. The mesoscale environment is characterized by a SBCAPE gradient of 500-2000 J/kg, precipitable water (PW) values of 1.4-1.7 inches (near the 90th percentile, per IAD sounding climatology), and effective bulk shear of 30-45 kts. MRMS estimates hourly rainfall totals as high as 1-2" in association with WSW-to-ENE training elements in the most intense multi-cell clusters, but fairly progressive storm motions (averaging near 20 kts) with more semi-discrete cells has tended to limit localized totals to 1". Going forward, there could be more substantial organization of convection going into the early evening hours given the overall favorable environment for heavy rainfall. The area of greatest concern in the near term is along the Blue Ridge Mountains from the eastern tip of WV southward to Shenandoah NP, as well as eastward into the DMV region. While hi-res models are not in the best agreement (with the HRRR in particular really struggling to properly initialize the the convection that is already ongoing), the best signal for heavy rainfall is located in this area (with fairly good agreement between the 18z HREF PMM and experimental 12z REFS PMM, suggesting localized 2-3" totals). There was also a distinct uptick in the 18z HREF 40-km neighborhood 3" exceedance probabilities (largely due to the addition of the 18z NAM-nest), which indicate 30-50% odds for localized 3" exceedance (through 03z). Given 3-hr FFG as low as 1.0-1.5" (mainly across northern sections of the MPD, including the aforementioned area of concern), isolated to scattered instances of flash flooding are likely. Convection should decrease substantially in coverage by 03-04z with waning instability and increasing convective inhibition. Churchill ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-mdYoAd0Hn_BrnMbqGyn2_P9vSuI-RA8SinqHC4y-e1RNcxsNaxZ57tvWMTsAXa-dH8-= fxWKHq3-neq0PTJwq8-qobQ$ for graphic product... ATTN...WFO...AKQ...CTP...LWX...PBZ...RLX...RNK... ATTN...RFC...ALR...RHA...TIR...NWC... LAT...LON 40287932 40237883 39887815 39487738 39107685=20 38617697 38007695 37317740 37047812 37157854=20 37567865 38277858 38867921 39168012 39768049=20 40098017 40247979=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) .