A series of training thunderstorms produced extremely high rainfall across portions of Patrick and Carroll Counties in Virginia during the predawn hours of August 28th. This resulted in areas of flash flooding, mainly in the headwaters of the Smith River and the Ararat River, with extensive river flooding observed in Mount Airy, NC.
The event began with a stationary front draped near the border of Virginia and North Carolina early on the 28th as an upper level disturbance began passing across the lower Great Lakes, placing the central Appalachians in an area of favorite lift. The disturbance triggered a southeasterly wind shift across the foothills of the Blue Ridge in southern Virginia and northern North Carolina, bringing an increase of deep moisture northeast from the Piedmont of North Carolina. Precipitable water values were estimated to be|between 1.9 to 2.1 inches across Surry County by 3:00 am EDT on the 28th, while Mixed-Layer CAPE values remained around 500 J/Kg through much of the night.
Convection initiated after sunset on the 27th as a few slow-moving showers across southern Patrick County, Virginia. Coverage and intensity of the slow-moving activity only increased as the evening progressed, with a band of showers and embedded storms forming along the Highway 58 corridor by midnight, that was advancing northeast toward the crest of the Blue Ridge. In western Patrick County and southeast Carroll County, Virginia, 4 to 7 inches of rain fell across the entire headwaters of the Ararat River, with radar estimated values of around 9 inches near the town of Ararat, VA. he flooding progressed south into Mount Airy, NC, where the Ararat River flowed out of its banks and flooded areas of the town along the river channel, with the river cresting at 23.71 feet.