Flash Flood — Floyd, Virginia

2015-09-29 · near Shelors Mill, Floyd, Virginia

Event narrative

Widespread flooding occurred across the county but was concentrated in Route 8 corridor. Several swift water rescues were made and numerous roads were closed and many damaged. A van was swept off of Meadows Creek Road and the driver, a college student, was rescued. In addition, 13 homes were destroyed, 12 homes received major damage, 15 homes minor damage, and 42 other homes affected, for a total loss of $2.3 million dollars. The worst flooding appeared to be in the Sowers Mill Dam Road and Little River Road areas. According to county officials additional commercial and agricultural losses ran about $400,000. Road damage totaled an additional $400,000 per the Virginia Department of Transportation. Local officials described it as one of the worst weather disasters in county history. The Little River which runs through much of Floyd County was responsible for much of the damage. Residents in the Sowers Mill Dam Road area said the river rose 20 to 25 feet during the flood. The river gage on the Little River further downstream at Graysontown along the Pulaski-Montgomery county line reached a stage of 12.68 feet (flood stage = 8 ft), the 3rd highest at the current datum and highest since Hurricane Agnes in 1972.

Wider weather episode

One of the most high-impact flood/flash flooding episodes in recent years in the Blacksburg Hydrologic Service Area (HSA) developed over a several day period but culminated September 29th. An unusual weather pattern became established around September 25th with very slow-moving and strong high pressure building across New England and low pressure over the southeastern U.S. combining to bring strong easterly flow into the southern Mid-Atlantic along with abundant moisture. Rainfall ending 12z on the 25th was generally confined to the southern portions of the HSA with up to 1 inch in parts of the North Carolina piedmont into southside Virginia. The rains became much heavier and widespread over the next two days with 1 to 4 inches ending at 12z on the 26th and another 1 to nearly 5 inches ending at 12z on the 27th. Over the next five days rainfall was nearly constant in some areas with pulses of heavier rainfall but with the heaviest amounts concentrating across the VA Blue Ridge mountains, mainly in Patrick, Floyd, Roanoke, Henry and Franklin counties. The maximum 5-day rainfall totals ending at 12Z (8 AM) on the 30th ranged from 10 to 16 inches in parts of Patrick and Floyd counties. Some of the higher totals equate to anywhere from a 100 to 500-year event per NOAA Atlas 14. The extremely wet soils set the stage for the severe flash flooding early on September 29th into the afternoon. Several bands of intense rainfall tracked across parts of the same counties mentioned above and also including Montgomery County over a 6 to 12 hour period from 0200 LST to 1400 lST (06z-18z) prompting the issuance of two Flash Flood Warnings for parts of eight counties and several cities at 943 AM (EDT) and 1019 (EDT) AM. It was difficult to differentiate between the onset of flash flooding from the longer duration flooding that was developing or underway as well. No matter the type, by mid-morning numerous reports of flooding and several high water rescues had been reported across a wide area, but most notably in parts of Patrick, Floyd, Montgomery, Roanoke and Henry counties. Local states of emergency were declared in Floyd and Patrick counties due to the widespread flood impacts with water rescues, some homes damaged and dozens of roads closed due to flooding or trees brought down in the saturated soil.

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Source: NOAA Storm Events Database, event_id 601960. Narrative written by the NWS forecast office that issued the report.