Flash Flood Guidance
Issued by NWS
Issued by NWS
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282 AWUS01 KWNH 262115 FFGMPD PAZ000-MDZ000-VAZ000-NCZ000-WVZ000-OHZ000-TNZ000-KYZ000-270113- Mesoscale Precipitation Discussion 0330 NWS Weather Prediction Center College Park MD 514 PM EDT Sun May 26 2024 Areas affected...PortIons of the Upper OH Valley and the Central Appalachians Concerning...Heavy rainfall...Flash flooding possible Valid 262113Z - 270113Z SUMMARY...A long-lived QLCS with heavy showers and thunderstorms will be crossing through portions of the upper OH Valley and the central Appalachians over the next few hours. Given locally wet antecedent conditions, the rainfall may be enough to cause some instances of flash flooding. DISCUSSION...The latest satellite and radar imagery shows a long-lived and severe QLCS advancing quickly east through portions of the upper OH Valley, and this will be reaching into portions of the central Appalachians over the next couple of hours. The downstream thermodynamic environment across the central Appalachians is moderately unstable with MLCAPE values as high as 1000 to 1500 K/kg across areas of eastern OH/southwest PA and much of WV. However, a stronger pool of instability is noted farther south over eastern TN involving the broader Cumberland Plateau region where some MLCAPE values are as high as 2000 to 3000 J/kg. Rainfall rates with the storms are likely to be highest over areas of eastern TN and far western NC where the greatest instability and concerns for more discrete cell-development ahead of the remaining QLCS will occur over the next few hours. Rainfall rates here will likely approach or exceed 2"/hour, with some spotty 3 to 4 inch totals possible. Farther north across much of WV and into eastern OH and especially southwest PA, the progressive nature of the QLCS will limit overall storm totals to 1 to 2 inches, but there may be some rainfall rates of up to 1 inch in as little as 30 minutes as the initial convective line arrives. The activity should tend to maintain some convective vigor given the downstream instability environment, and areas even east of the Appalachians may see convection survive heading later into the evening hours. Large areas of the central Appalachians in general are rather moist, and portions of northern WV, southeast OH and southwest PA saw heavy rains last evening and overnight which have resulted in elevated streamflows. Given this and the locally rugged terrain helping to enhance runoff further, some localized areas of flash flooding will be possible over the next few hours. Orrison ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...CLE...CTP...GSP...JKL...LWX...MRX...OHX...PBZ... RLX...RNK... ATTN...RFC...LMRFC...MARFC...OHRFC...SERFC...NWC... LAT...LON 41288003 40937901 39867845 38117909 36388086 35688230 35408386 35958475 36838369 37908226 39298163 40338167 41128093