Flash Flood Guidance
Issued by NWS
Issued by NWS
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309 AWUS01 KWNH 260011 FFGMPD VAZ000-NCZ000-WVZ000-TNZ000-260600- Mesoscale Precipitation Discussion 1059 NWS Weather Prediction Center College Park MD 810 PM EDT Wed Sep 25 2024 Areas affected...Southern Virginia into West Virginia Concerning...Heavy rainfall...Flash flooding possible Valid 260009Z - 260600Z SUMMARY...Localized flash flooding into the overnight as moisture ahead of Helene streams over a stationary front and into the eastern slopes of the Appalachians. DISCUSSION...The northern end of the moisture plume in advance of Helene is lifting across NC and will cross a persistent front over southern/southwestern VA rest of the evening. Scattered thunderstorms have broken out along this frontal zone and to the west there remains terrain enhanced rainfall along the eastern slopes of the Appalachians. There were two main areas of heavy rain in this region over the past day, farther east over the NC/VA border last night, and earlier today west of the stationary front. The main focus for heavy rain into the overnight is generally progged to be between these two areas, but this is where the Blue Ridge is, so a bit of a broader swath as been drawn for possible flash flooding. Instability is sufficient with MLCAPE of 1000 to 2000 J/kg and moisture influx has been noted with low level southerly flow will increase from 15 to 30 kt through midnight which will reinforce PW around 1.7". Deep layer mean flow is around 30kt which should keep activity east of the Blue Ridge progressive, but localized rainfall over 1"/hr may cause some flooding issues. Terrain enhanced rates of 1"/hr will also cause concern...flash flooding is considered possible into the overnight. Further activity in the southern Mid-Atlantic is likely into Thursday, so please be on the look out for updated heavy rainfall info. Jackson ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...AKQ...LWX...MRX...RAH...RLX...RNK... ATTN...RFC...LMRFC...MARFC...OHRFC...SERFC...NWC... LAT...LON 38287993 37917941 37677879 37207740 36577758 36257848 36118091 36658225 37368181 37738106 38278046