Heavy Rain — Botetourt, Virginia

2022-08-25 · near Amsterdam, Botetourt, Virginia

Event narrative

A personal weather station (Weather Underground: KVADALEV11) recorded 2.64 inches of rain from a thunderstorm, falling during a 90-minute period between 6:50 pm and 8:20 pm on the 25th. Rainfall rates were at one point observed as high as 4 inches per hour. This is between a 25- and 50-year rainfall event per NOAA Atlas 14 estimates. Runoff from this rainfall entered Tinker Creek.

Wider weather episode

High pressure was established across the lower Mid-Atlantic during the evening of August 25th, allowing for only widely-scattered showers and thunderstorm development, mainly confined along and west of the Blue Ridge. Wind speeds in the lower levels of the atmosphere were generally less than 10 mph from the northwest, supporting only very slow movement of the convection. Dry air associated with the high pressure limited precipitable water values that evening to 1.23 inches per the August 26th 00Z upper air sounding performed by NWS Blacksburg, which is very near the 50th percentile for late August. One slow moving thunderstorm developed over northern Roanoke County and tracked slowly southeast along the Botetourt County line. The storm intensified near the community of Cloverdale and produced heavy rainfall between 8 pm and 10 pm EDT at rates of 2 to locally 4 inches per hour. Some flooding issues were noted, particularly along Tinker Creek which rose 8 feet in under 2 hours. While the rainfall was intense and justified the issuance of a flash flood warning given the higher population density of the area, the small footprint of the heavy rain, semi-rural nature of the area impacted and the late evening hour limited evidence of flash flooding in the area.

View location on OpenStreetMap → (37.4010, -79.9030)

Source: NOAA Storm Events Database, event_id 1041393. Narrative written by the NWS forecast office that issued the report.