UPDATE 6:20 PM: The severe thunderstorm watch has been cancelled for almost all of Southwest Virginia — and the few counties that remain near the Tennessee line will soon be out of it, too, as storms have moved to the south. The “derecho shield” — a band of morning rain and storms in Ohio and western West Virginia — worked today, providing a column of rain-cooled air that a storm cluster that caused widespread wind damage in northern Illinois and Indiana couldn’t cross. Downslope westerly winds and cloud cover kept the rest of our severe weather potential in check. The wind dynamics, surface and aloft, were certainly there for wind damage if there had been more intense storms, but there weren’t, this time. East of Interstate 77, there hasn’t been much rain, either. END UPDATE
Not surprisingly, a severe thunderstorm watch has been issueduntil 8p.m. for most of Virginia, excluding the far southeast counties, and a few in the far southwest under a different watch til 7 p.m. Rather than one major storm complex to watch, we have a variety of different storms to monitor: a bow echo line with a long history of wind damage sliding into far southwest Virginia, and scattered clusters/individual storms in the mountains of Virginia and West Virginia moving southeastward. Clouds and early showers/storms are limiting instability some in parts of western Virginia, which may curtail the severe weather risk some west of the Blue Ridge, but wind dynamics are unusually strong for July, typically a time of anemic upper-air and surface wind. Storms with wind damage are possible this afternoon throughout the watch boxes, and with stronger low-level wind shear than is typical in July, a few rotating storm structures (i.e. supercells) may occur with some hail and localized winds possible. The tornado risk is low, but somewhat higher than what we saw June 29, which was entirely a storm outflow situation. Locations that have stayed in sunshine this morning and heated up– primarily east of the Blue Ridge — will have the best chance of higher-end storms, but severe weather is possible anywhere in and near the watch boxes this afternoon. Keep an eye on the sky and on radar.