UPDATE 8:35 PM: Severe thunderstorm warning until 9:30 p.m. for several counties from West Virginia line east to Roanoke, north to Bath County, south to Giles County and Radford. Includes Blacksburg-Christiansburg area, Craig County, Botetourt County, Alleghany County. Some wind gusts in excess of 80 mph possible. Strong winds may move out ahead of storms several miles. END UPDATE
A severe thunderstorm watch has been issued until 1 a.m. for most of Virginia, excluding only the far southwest and southeast corners. A fast-moving “bow echo” line of storms is racing southeastward through the Ohio Valley, preparing to enter West Virginia as of just before 6:45 p.m. There have been hundreds of reports of wind damage already as these storms have been racing through the Ohio Valley. The Appalachians should not be much of an obstacle for them, as they are for some storms, as it is extremely hot and unstable on both sides of the mountains, and the storms are being propelled southeastward by a cold air pool of their own making. Humidity levels have also risen, with dew points in the 60s in most locations, so they have moisture to work with. This is a potentially very dangerous situation, as long-lived bow echoes like this — sometimes known as “derechoes” — can produce widespread wind damage to trees and power lines. The exact movement is a little uncertain, but it appears that at least areas north of the U.S. 460 corridor (Bluefield-Blacksburg-Roanoke-Lynchburg) will experience strong to severe storms between 8 and 11 p.m. this evening, and it’s very possibly the storm cluster may sag all the way to the North Carolina border.
My last blog entry linked here looks at several of today’s hot superlatives, including record-setting highs of 103 at Roanoke and 95 at Blacksburg. The incredibly warm lows of this morning — 84 at Roanoke, 78 at Blacksburg — will most likely fall by the wayside when this storm line pushes through, even if it were to miss to the north or diminish in intensity, as the cooling outflow winds will very likely take both locations below those numbers this evening, thereby supplanting what would have been the warmest lows ever reported at both sites. So at least one amazing aspect of this day, the hot morning breezes, will stick in our memories but likely not the record book.