1. Flash Flooding Across the Southern Appalachians: An Abbreviated Climatology with Forecasting Methods and Techniques Anthony D. Phillips, David A. Call, and Jill S. M. Coleman Department of Geography Ball State University

2.  Analyze the spatial and temporal extent of flash floods across the southern Appalachian Mountains  Create a hydroclimatology using credible reports  Examine the influences of regional topography and environmental characteristics (soil type, land use, etc) on the spatial distribution of flash floods  Gather information on the synoptic and mesoscale environments conducive to flash flooding across the region

3.  Residents of the southern mountains are at greater risk due to: –Steep, complex terrain –Rapid accumulation of precipitation –Competition with mountain streams for roads, bridges, housing, etc. –Mountaintop removal

4.  Previous hydroclimatological research has been limited to individual NWS WFOs (Gaffin and Hotz, 2000; Stonefield and Jackson, 2009).  Thorough, regional analysis will provide a better understanding of the extent of flash floods  Southern Appalachian Mountains: –Mountainous areas south of Mason-Dixon Line (~39.7° N) –Locations within the USGS Appalachian Highlands physiographic division; namely the Appalachian Plateau, Valley and Ridge, and Blue Ridge provinces

6.  Data obtained from the National Climatic Data Center –Storm Data from 1950 to 2010  Focuses on events after the Modernization and Restructuring (MAR) of the NWS in the mid-1990’s –Storm reports and verification –Abbreviated climatology: January 1, 1996 to December 31, 2010  Storm Data reports listed as either “flash flood” or “flash flooding”  Multiple events with similar/exact dates and locations were consolidated into a single event

10. July 2007 July 2003  Frequency of events per year  Noticeable variations, especially between drought (’99, ‘07) and non-drought years (‘03)

11.  Number of events that occurred during each month  Frequency of events increases dramatically starting in May –Substantial decrease in October –Secondary peak in January

13.  Events per time of day divided into 1-hr increments  Number of events increases during afternoon/early night hours

14. Flood Severity Index (FSI) developed at the Blacksburg WFO. Flood severity scaleFlood categoryDescription FS1Nuisance Few road closures, creeks and streams out of their banks. (Little or no damage) FS2Minor Numerous road closures, numerous creeks and streams flooding, basement flooding, mudslides (Light Damage <$100K) FS3Moderate Some rescues, evacuations, few houses/businesses flooded. (Considerable damage $100K- <$500K). FS4Severe High Threat to Life/Property, several rescues, evacuation of and/or damage to several homes/businesses (Major Damage $500K-<$2M). FS5CatastrophicVery High Threat to Life/Property, numerous rescues, evacuations of and/or damage to homes/businesses, (Catastrophic Damage ≥$2M).

20.  Future research will include examining the synoptic and mesoscale environments favorable for flash flood events across the southern Appalachians –Forecasting methods specific to the region  Additional spatial statistics such as average nearest neighbor and Geographically Weighted Regression –Geographically Weighted Regression (GWR) will examine the relationships between prior flash flood events and other environmental characteristics across the region  Expansion of the study area to include the eastern United States

21.  4,938 unique flash flood reports from 1996 to 2010  71 fatalities and 64 injuries  As expected, greater number of events during warm season months and during afternoon/overnight hours  Higher fatality rates in regions with higher mean percent slope  Future work will include: –Additional statistical tests –Flash flood forecasting techniques  Results will assist meteorologists and hydrologists in forecasting flash flood events For more information: Anthony Phillips http://www.wx4sno.com wx4sno@vt.edu