A Review of the 23 June 2016 West Virginia Historic Flash Floods: Use of Emerging Observational Technologies to Monitor Threats

On 23 June 2016, repeated waves of thunderstorms with heavy rainfall moved across portions of central and southeastern West Virginia in the vicinity of a mesoscale surface boundary. During an 8-12 hour period, as much as 200-250 mm of rain fell across some areas, including parts of Kanawha, Fayette, Nicholas and Greenbrier Counties. According to Annual Exceedance Probability (AEP) statistics, these amounts would be considered a “1 in 1,000 year event”, even if occurring in a 24-hr period.  As a result of this extreme rainfall, major flash flooding and river flooding occurred, causing 23 total fatalities in West Virginia (15 in Greenbrier County), multiple injuries, and thousands of homes and businesses damaged or destroyed.  Flash Flood Emergency wording was included in warnings for the hardest hit areas as the extreme magnitude of the event began to unfold.

This review will focus primarily on the use of emerging technologies, some already available operationally in the National Weather Service, to monitor the rainfall and potential magnitude of runoff.  Radar-based rainfall estimates proved especially useful given there were limited real-time rain gauges in operation across this region. In particular, given that much of this rainfall occurred in between two WSR-88D radars and with partial beam blockage in some portions where the heaviest rain fell, the Multi-Radar Multi-Sensor (MRMS) precipitation products, available in real-time at NWS Forecast Offices since 2015, proved quite accurate and thus critical in this event.  In addition, output from the Flooded Locations and Simulated Hydrographs (FLASH) program will be shown, specifically from the Coupled Routing and Excess Storage (CREST) hydrologic model, of which MRMS rain rate are the primary observational precipitation input. FLASH is under development in partnership with the National Severe Storms Laboratory (NSSL), the University of Oklahoma (OU), the Cooperative Institute for Mesoscale Meteorological Studies (CIMMS), and the  National Oceanic Atmospheric Administration (NOAA), and is expected to eventually be baselined into NWS operations.  The specific benefits of this output, with the assumption it is available to field office in real-time, will be described for this event.