August 20, 2014 Severe Weather Outbreak

A shelf cloud that moved through Murphy, NC ahead of a squall line on August 20, 2014 . Photo courtesy of Shane Goebel.
 
A wall cloud associated with a rotating supercell thunderstorm in Blount County, TN. Photo courtesy of Ginger Ricketts.
 
Another episode of severe weather occurred late this summer as widespread thunderstorm activity (fueled by abundant Gulf moisture and a highly unstable atmosphere) produced widespread straight-line wind damage (with speeds as high as 80-90 mph in some cases) and large hail 1 to 2.5 inches in diameter. Though not as unusual as the tornado outbreak that occurred in late July, widespread wind damage and hail events are certainly less common in the late summer than they are during the Spring months of March, April and May.
 
140820_rpts Filtered Reports Graphic
Map of all the storm reports from August 20, 2014 across the nation. Note the high density of hail and wind damage reports across our area!
 
An initial cluster of supercell thunderstorms developed along the northern Cumberland Plateau by early afternoon and began drifting southeastward into the Tennessee Valley. These storms generated some strong downburst winds across Loudon, McMinn and Monroe Counties, which produced some significant damage to some structures and downed numerous trees and power lines across the aforementioned counties. One severe thunderstorm across Loudon County, produced 80-90 mph straight-line winds in the town of Philadelphia, TN, completely destroying an older house and a couple of barns. These storms later congealed into a larger line as they raced across the southern Valley and southern Cumberland Plateau region of southeast Tennessee and southwest North Carolina, producing additional damage to trees and power lines through the early evening from their 60-70 mph outflow winds.