Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Apr 11 2024 18:11:54 AWUS01 KWNH 111811 FFGMPD PAZ000-VAZ000-WVZ000-OHZ000-TNZ000-KYZ000-120010- Mesoscale Precipitation Discussion 0152 NWS Weather Prediction Center College Park MD 210 PM EDT Thu Apr 11 2024 Areas affected...Portions of the Upper OH Valley Concerning...Heavy rainfall...Flash flooding possible Valid 111810Z - 120010Z SUMMARY...Some expansion of shower and thunderstorm activity is expected this afternoon through early this evening with pockets of heavy rainfall rates. This coupled with moist antecedent conditions may result in some instances of flash flooding. DISCUSSION...GOES-E IR/WV imagery shows a strong mid-level trough and an associated frontal zone currently crossing through the Mid-South and taking aim on the OH Valley. Strong forcing associated the energy aloft coupled with a gradually destabilizing boundary layer out ahead it will set the stage for gradually expanding areas of locally heavy showers and thunderstorms over the next several hours. Already the regional dual-pol radars show broken areas of shower activity impacting large areas of the Upper OH Valley. Overall, the instability profiles are rather modest though with MUCAPE values of 500 to 1000 J/kg, with the greatest pooling of this seen nosing up across central/eastern KY and western WV. However, over the next few hours, some additional boundary layer destabilization is expected which will drive an increase in convective coverage, and the latest GOES-E visible satellite imagery does show some areal breaks in the cloud cover facilitating an uptick in diurnal heating. Effective bulk shear values of locally 40 to 50 kts working in tandem with the instability, and rather moist low-levels should favor some relatively organized convective cells capable of producing heavy rainfall rates. PWs across the broader OH Valley region are on the order of 1.5 to 2 standard deviations above normal, and the latest CIRA-ALPW data shows mid-level moisture relatively concentrated over areas of eastern KY, central/eastern OH and western WV which will tend to support somewhat greater rainfall efficiency this afternoon. Rainfall rates across these areas may reach as high as 1.5"/hour with the stronger cells and this is supported by the consensus of the 12Z HREF guidance. Some localized repeating/training of cells will be possible by late afternoon as the convection attains greater levels of organization, and with these heavier rates, some localized swaths of additional rainfall reaching 2 to 3 inches will be possible. The antecedent conditions are locally rather sensitive, with moist soils and locally elevated streamflows. So, the additional rainfall threat this afternoon may encourage some more notable runoff concerns and potential for flash flooding. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7UaLkMEd3uLMZfxK52cWecAkKKYx6-DUhoi1cqmDQrFmUT0RkOOmrlz3YVKXRaNMpDnM= o-7utmcYgSK-xqSWzuO4CGE$ for graphic product... ATTN...WFO...CLE...ILN...JKL...LMK...MRX...OHX...PBZ...RLX... ATTN...RFC...LMRFC...OHRFC...NWC... LAT...LON 41858084 41727983 41197931 40787921 39927947=20 39088009 38118110 36908234 36118301 35778361=20 35768402 36148493 37178521 38638458 40068366=20 41238235=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) .