UPDATE 11 PM: While it doesn’t appear a well-organized cluster of storms will plow through Southwest Virginia tonight, some storms with heavy rain and gusty winds have been occurring primarily west of I-77 and north along the Virginia-West Virginia border. These storms may linger a while overnight, even drift north or east a little bit. We’ll have chances of storms Wednesday through Friday as a cold front approaches from the west and daily warmth and humidity continue. END UPDATE
Some counties in Southwest Virginia west of Interstate 77 are under a severe thunderstorm watch until 10 p.m. because of cluster of thunderstorms that has actually propagated eastward out of Monday’s tornado outbreak in Oklahoma. The line of storms now in central Tennessee and Kentucky is encountering more unstable, sun-heated air as it moves eastward and poses mainly a large hail/strong winds threat eastward. Though there are some reasons this line may diminish later crossing the Appalachians or running out of daylight, I would advise Roanoke/New River valley folks to keep at least an eye and an ear out for this (RADAR LINKED HERE) as it approaches this evening. Sometimes these “mesoscale convective systems” — MCS’s, in weather geek talk — sort of get a mind of their own about where and how fast they want to travel, as their updrafts and downdrafts actually change the weather conditions around them, defying forecast models. The cluster is moving east-northeast, so it’s pretty much on a beeline for all of Southwest Virginia, IF it were to maintain its strength and heading. Other scattered showers and storms may pop up this afternoon simply because of the heat and humidity.
At left is an image of a possible tornado photographed by the Hokie Storm Chasers on Monday somewhere near the Red River (southern Oklahoma or northern Texas). We say “possible” because it is unclear if the funnel is in contact with the ground behind the cluster of trees. As you know, Monday was a vicious severe weather event in the southern Plains, particularly because of the deadly tornado at Moore, Okla., in the Oklahoma City suburbs. That storm has recently been rated EF-5, the highest on the scale, based on some new findings by the National Weather Service office in Norman, Okla. The Hokie Storm Chasers are in Texas today on what is likely to be their last day of tagging severe storms before the first team returns home. A second team is headed out on Sunday or Monday for 10+ days — I will be on that trip as a co-leader, which I will be posting about on the Weather Journal blog. In the Weather Journal column also posted at top, I discuss the current upsurge in tornadoes as I prepare for this trip.