Flash Flood in Virginia, January 19, 1996

An unprecedented combination, in recent history, of unseasonably warm, humid air overriding a dense snowpack estimated between 12 and 18 inches (but up to 2 feet or more at higher elevations) caused nearly the entire pack to vanish in a 12-hour period. The unseasonably warm air was drawn northward around the circulation of a deepening storm west of the Appalachians late on the 18th and early on the 19th. The melting snow and additional rainfall produced widespread flooding and flash flooding on the 19th.Strong low-level southeast flow developed by late afternoon on the 18th. Initially, colder temperatures in sheltered valleys slowed the rate of snow melt while the warm moist air mass attacked the snow pack at higher elevations. By mid-evening, however, even the lower elevations were warming rapidly. Flash flooding began at around the same time as the onset of heavy pre-frontal rains. Heavier showers fell over the same areas between 0400 and 0800EST, causing acute and widespread flooding and flash flooding. Some areas received between 2 and 4 inches of rain during this period. Thunderstorms developed as the line moved into eastern Loudoun Co between 0900 and 0930EST. Some of the higher totals reported by automated rain gages (including some snow melt) were nearly 5 inches. Monterey (Highland Co) received 4.71 inches, Front Royal (Frederick Co) had 4.32 inches, Hogback Mountain (Warren Co) reported 3.76 inches, and Woodstock (Shenandoah Co) had 2.43 inches.Some of the most pronounced damage occurred in Shenandoah Co near the town of Woodstock. One hundred acres of farmland were inundated, a reported 799 homes sustained damage from flood waters, as did a restaurant in Edinburg. There were numerous water rescues, but no fatalities were reported. Numerous local roads werre closed, as were several state and federal highways, due to high standing water or creeks raging out of their banks.