Flash Flood — Lynchburg (c), Virginia

2023-07-15 · near (lyh)glenn Fld Lynch, Lynchburg (c), Virginia

Event narrative

Water overflowing from a tributary of Simons Run was observed covering Simons Run Road as much as a foot deep in spots. There was no damage to the road and it was reopened after the flooding receded. A tree was also blown down across the road by thunderstorm winds.

Wider weather episode

A trough of low pressure was situated from Buckingham County, VA southeast through Alleghany County, NC during the evening of the 15th, while a cold front was advancing eastward across the mountains. A wave of low pressure passing along the front over western North Carolina served to increase low level winds into the 20 kt-25 kt range from the south, tapping into deep moisture. By 8 pm EDT, precipitable water values across Campbell and Appomattox Counties had risen as high as 2.1 inches, which is around 2 standard deviations above normal for mid-July for central Virginia per NWS gridded climatology estimates. Instability was also observed to be extremely high, with surface-based CAPE values in the 2,500 to 3,000 J/Kg range. By 10 pm EDT, storms that had made steady progress southeast across Bedford County were beginning to stall along the surface trough stretching across Campbell and Appomattox Counties. Steady flow of moisture from the south continued to feed into the line of storms, with cells beginning to train over the same locations. High instability continue to support rainfall rates within the stronger cells of 4+ inches per hour. By 11 pm EDT, CREST Unit Streamflows were beginning to exceed 600 cfs per mi^2 across the southern portion of the City of Lynchburg into northern Campbell County, persisting as such through 1 am EDT on the 16th, when heavy rain exited the area. FLASH 3-hour Average Recurrence Intervals were observed approaching a 200-year rainfall event just north of the Town of Rustburg. This resulted in considerable flooding across Campbell county and Lynchburg.

View location on OpenStreetMap → (37.3378, -79.2020)

Source: NOAA Storm Events Database, event_id 1124960. Narrative written by the NWS forecast office that issued the report.