Flash Flood in Pulaski County, Virginia

A total of 4 to 6 inches of rain fell within the headwaters of Big Macks Creek. Of this total, 3 to 5 inches of rain fell in 1.5 hours. Max Creek Road was impassible, with 2 of the 7 bridges leading into Camp Powhatan sustaining damage. The estimated water depth in Big Macks Creek was 9 feet higher than base flow. Debris was observed having been washed onto some of the bridges. Runoff caused Lake Powhatan to rise 3 to 4 feet.

Deep moisture pooled across the lower Mid-Atlantic during the afternoon and evening of the 26th to the south of a stationary front draped across northern Virginia. Precipitable water values were estimated in the 1.8 to 1.9 inch range across the New River Valley area of Virginia per Storm Prediction Center Meso-analysis, while CAPE values were estimated to range from 1,500 to 2,000 J/kg during the evening. A series of thunderstorms were observed training across the southern half of Pulaski County, VA beginning around 6 PM EDT, with cells passing from west to east across the area through 9 PM EDT. Multiple cells were estimated by radar to have produced rainfall rates of 3 to 4 inches per hour. Dry antecedent conditions were noted for all of Pulaski County, with D2: Severe Drought highlighted by the U.S. Drought Monitor. It was estimated that between 4 and 6 inches or rain fell within the headwaters of Big Macks Creek. MRMS FLASH did not present impressive returns, and was offset from the Big Macks Creek basin by 3-5 miles to the west. FLASH estimated the rainfall reached into the 50 to 70-year Average Recurrence Interval range for a 6-hour duration along a narrow north to south strip west of the basin, with rainfall totals reaching 180 percent of the 6-hour Flash Flood Guidance. CREST Unit Streamflow ranged from 125 to 250 cfs per mi^2 during the event.