Flash Flooding Across the Southern Appalachians: Flash Flooding Across the Southern Appalachians: An Abbreviated Climatology with Forecasting Methods An Abbreviated Climatology with Forecasting Methods

and Techniquesand Techniques

Anthony D. Phillips, David A. Call, and Jill S. M. ColemanAnthony D. Phillips, David A. Call, and Jill S. M. ColemanDepartment of GeographyDepartment of Geography

Ball State UniversityBall State University

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

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

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

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

July 2007

July 2003

Frequency of events per year Noticeable variations, especially

between drought (’99, ‘07) and non-drought years (‘03)

Number of events that occurred during each month Frequency of events increases dramatically starting in

May– Substantial decrease in October– Secondary peak in January

Events per time of day divided into 1-hr increments Number of events increases during afternoon/early

night hours

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

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