Flood in Pulaski County, Virginia

The New River near Allisonia, VA (ALSV2) crested at a stage of 8.15 feet (32,000 cfs) at 1:45 am EST on 1/10/24, rising above the minor flood stage of 8.0 feet. This is the highest crest since 11/12/2020. This event is about a 2-year ARI (50% AEP) per USGS StreamStats. A few spots on roads running along the river were briefly covered by water, however no damage was reported during this event.

A deep, negatively tilted upper level trough and associated occluded front passed from the central Mississippi River Valley on January 9th toward the lower New England region by the morning of the 10th. Strong southerly wind flow ahead of the upper trough carried deep moisture from the Gulf of Mexico northward into the Carolinas and the lower Mid-Atlantic. Precipitable water values ranged from 1.1 inches across north-central Virginia to nearly 1.5 inches over the border between Virginia and North Carolina by early afternoon on the 9th, or anywhere between two and three standard deviations above normal for January. Precipitation fell mainly as rain during a 12 to 15 hour period on the 9th, mostly at rates of a half inch per hour or less. However, a convective band pushed from North Carolina across the foothills and Piedmont of southern Virginia during the afternoon, producing rates of locally two inches per hour. Rainfall totals varied from 1.5 to 2.5 inches for portions of Virginia located west of the Blue Ridge Parkway, and between 2.5 and 3.5 inches along and further east of the parkway, averaging between 2-year and 5-year precipitation totals for a 12 hour duration per NOAA Atlas 14 Point Precipitation Frequency estimates. Given that multiple precipitation events having passed across the region since late November 2023 had allowed stream flows and soil moisture to improve from the Moderate to Severe Drought conditions, the region was more susceptible to flooding. The long-duration rainfall event allowed streams to rise gradually, making for numerous instances of mainly minor areal and riverine flooding. However, flash flooding occurred across the Piedmont, particularly across Pittsylvania County, in the wake of the convective band. Multiple roads and bridges were reported flooded and impassible because of the rainfall, with a few becoming severely damaged.