UPDATE 5:15 PM. The severe thunderstorm watch is being cancelled west to east — it was recently removed for Roanoke and westward — as the storms continue to move east and leave behind a stablized atmosphere. There are scattered reports of wind damage, including about 1,400 without power in Roanoke County. END UPDATE
UPDATE 2 PM: As expected, a severe thunderstorm watch has been issued for most of Virginia except extreme southwest and southeast corners, effective until 7 p.m. In addition to a line of storms moving out of West Virginia, several small but intense cells have developed along the Blue Ridge, including over parts of the Roanoke area. END UPDATE
UPDATE 1:30 PM: The Storm Prediction Center has highlighted much of our region for a possible severe thunderstorm watch, with damaging winds the main threat, as storms moving through West Virginia approach the region this afternoon and new storms develop near the Blue Ridge. You can check latest Radar / Futurecast in right margin. END UPDATE
UPDATE 8:45 AM, 7/27: In this morning’s Storm Prediction Center, Southwest Virginia is between areas of greatest risk of severe weather today. (The most recent update pulls slight risk a bit west of the map at left, to the Blue Ridge.) Storms are expected to develop as a cold front and upper-level disturbance interact with heat and moisture, but the more intense heating/instability will be east of us and the better lift will be west of us. A few storms with heavy rain and gusty winds will be possible in Southwest Virginia. Once again, it will be a situation where one location gets a windy downpour with big lightning flashes, while someone a few miles away hears some thunder and gets no more than sprinkles. END UPDATE
UPDATE 12:30 AM: It’ s still possible some of the storms in West Virginia could drift into part of our region overnight. More likely, though, will be redevelopment of storms in hot, humid air Friday as the cold front pushes in and outflow boundaries from Thursday’s storms interact with the same juicy air mass. Severe storms will be possible, but likely not the tornadoes and derecho (yes, i just used that word) that went from Ohio to New York on Thursday. With weaker upper air flow probable, it will be more the typical summer clusters with localized damaging winds, and maybe a squall line or two developing on the front and/or an outflow boundary. Always hard to pinpoint exactly how it will go until storms start popping. END UPDATE
Not quite 100 in Roanoke today — 98 for an official high. Blacksburg didn’t even make 90, topping out at 89.
The Storm Prediction Center issues “mesoscale discussions” for potential severe storm areas — those that are under watches, could soon be under watches, and those that may not warrant a watch. Early this evening, the red circles marking the active mesoscale discussions were east, north and west of Southwest Virginia. A very potent severe weather situation drawing a “moderate risk” zone and already some tornado reports has been unfolding north of us from Ohio across Pennyslvania into New York. A broken line of thunderstorms extends all the way from upstate New York to west Texas. So how will this affect our neck of the woods? One important difference in today’s setup compared to the infamous June 29 derecho setup is the mid to upper air wind flow — shown on this graphic from the Storm Prediction Center earlier today. The winds aloft are lined up more west-southwest to east-northeast, rather than northwest to southeast, and the faster winds (more barbs on the lines) are north of our region, not aimed directly at us. The result is that storms are moving more from the Ohio Valley toward the Northeast rather than rocketing southeastward at us. Some of the storms in Kentucky and Ohio will move into West Virginia later this evening, but they will be encountering unfavorable wind flow (downslope winds over the mountains often dries them out) well after the peak daytime heating has let up. It’s possible a storm cluster could gain enough momentum to get over the mountains late tonight or early Friday morning, but the best chance of seeing storms overnight will lie in eastern West Virginia and west of Interstate 77 in far southwest Virginia. Some scattered storms or clusters of storms may develop in northern/central Virginia east and north of Roanoke this evening as daytime heating and humidity punches into cooling air aloft. A better chance of storms for our region exists on Friday when the front actually moves through, cutting through the heat and humidity. The upper-level wind flow is not expected to be as favorable for organized severe weather as it has been to our north today, so we’re probably looking at a random jumble of storm clusters capable of producing some localized damaging winds. The “d-word” probably gets a rest in our region for another 48 hours.