Heavy Rain — Galax (c), Virginia

2013-07-11 · near Galax, Galax (c), Virginia

Event narrative

Urban flooding in Galax was reported as rainfall of 1 to 1.75 in a few hours was estimated by radar. NWS Cooperative stations Galax Radio (GLXV2) reported 1.75 and Galax Water Plant (GAAV2) 1.72 ending at 8 AM on July 12th. Route 89 and Givens Road were reported closed but Chestnut Creek did not even approach the Action Stage of 6 feet.

Wider weather episode

There was no substantial change in the setup conducive to heavy rainfall on the 11th with extremely high moisture (PWAT in excess of 2'), increasing afternoon instability and periodic impulses providing lift. Storms once again developed during the evening of the 11th, this time mainly over the eastern piedmont counties with the most intense rains focusing over parts of Danville City, Amherst, Buckingham, Campbell, Pittsylvania, Halifax, and Charlotte counties. Radar estimated rainfall showed widespread 2 to 4 inch rains across parts of this area but even higher amounts north from near Danville north into Pittsylvania County. Dual-Pol radar estimated over 10 inches (probably overestimated with legacy radar showing 6 to 8 inches) in the upper portions of Lawless and Dry Fork basins north of Danville which caused serious flash flooding in this area with roads and bridge damaged and several water rescues. Some of the very heavy rainfall was caught by a DCP rain gage in Randolph (RNDV2) where a 1-hour amount of 1.86' ending at 05Z was followed by 4.17' ending at 06Z for a 2-hour total of 6.03'. This rainfall at the Randolph River gage caused a nearly instantaneous rise on the river, which rose over 7 feet in four hours from 15.5' to 22.8' and exceeding flood stage. 24-hour rainfall from gages (again, most of which fell in a few hours) included Randolph DCP (RNDV2) 7.61', Charlotte Court House COOP (CHRV2) 5.21', Danville ASOS (DAN) 4.43', Danville 5.5 N CCR 4.41', Danville 4.9 NNE CCR 4.28' and Lynchburg 2.5 WSW CCR 3.42'. Danville ASOS set a date record for the 11th (ending at midnight) with 2.99' breaking the 1965 record of 2.00'. The 7.61 value in 24 hours for Randolph is very close to the 1 percent annual exceedance probability (100-year event). Runoff from this event into the Dan and lower Roanoke River basins prompted River Flood Warnings for a number of forecast points with generally minor to moderate flooding observed.

View location on OpenStreetMap → (36.6700, -80.9200)

Source: NOAA Storm Events Database, event_id 464492. Narrative written by the NWS forecast office that issued the report.