Debris Flow — Wythe, Virginia

2020-08-15 · near Porters Xrds, Wythe, Virginia

Event narrative

The Wythe County 911 Operations Center reported multiple debris flows taking place along VA Highway 94 in and around the community of Ivanhoe. Multiple rounds of thunderstorm activity, both on the 15th and in the days prior, resulted in saturated soil conditions. The multiple rounds on the afternoon of the 15th reached up to 1.5 times the 6-hour flash flood guidance, roughly a 5-year rainfall event per FLASH estimates.

Wider weather episode

Deep moisture returned to the lower mid-Atlantic region during the period August 12th - 15th, with precipitable water values ranging from 1.6 to 1.9 inches each day. A frontal boundary stalled near the Interstate 64 corridor provided a trigger for convection, supported aloft by passing upper level disturbances. Strong daytime heating contributed to deep instability, resulting in thunderstorms with high rainfall rates. Light winds aloft resulted in mean wind speeds generally 10 knots or less, indicating slow cell movement.

View location on OpenStreetMap → (36.8500, -80.9700)

Source: NOAA Storm Events Database, event_id 915963. Narrative written by the NWS forecast office that issued the report.