by William Perry
April is usually the beginning of our region's peak severe thunderstorm season. We saw several episodes of severe weather during this month, with the more significant episodes occurring early; on April 3rd and April 7th. During the afternoon of April 3rd, a line of thunderstorms developed in the warm sector ahead of a cold front. Most of the severe weather occurred east of the Blue Ridge mountains. Hail up to golf ball size fell in Eden, North Carolina.
Another round of severe thunderstorms erupted April 7th. This was in advance of a strong cold front, and a complex low pressure center over the Mississippi Valley. Storms were scattered in southeast West Virginia in the afternoon, then spread east during the late afternoon and early evening across the New River Valley into an organized line with embedded supercells. Numerous damaging winds and large hail reports were received with this batch of storms. Winds gusting from 60 to 75 mph occurred with hail as large as ping pong balls falling near the Clifton Forge area. This first line weakened as it moved east of the Blue Ridge around 800 pm EDT. A few more severe storms erupted within another area of showers later in the evening, bringing nickel size hail to Grayson County.
The rest of month was relatively quiet with a just a handful of severe thunderstorm events.
May saw a couple of decent severe weather episodes. On the 14th, a frontal system was moving into the area, with colder air aloft. Thunderstorms developed across the Mountain Empire of Southwest Virginia by mid morning on the 14th, forming into an organized area that stretched from the New River Valley to the North Carolina mountains by 1030 am. Hail was the main severe weather element that occurred during this event. The storms moved east through the piedmont by early afternoon. Severe thunderstorms spawned tornadoes just south of our area of responsibility with this system.
May 26th, a trough of low pressure was located east of the Blue Ridge, while a cold front moved into the Ohio Valley. The air was unstable in the piedmont, with a strong low level jet helping to promote thunderstorm development. Most of the severe weather occurred late in the afternoon in southside Virginia and the northwest piedmont of North Carolina. The worst of the severe thunderstorms occurred in Pittsylvania county, near the community of Climax. This storm produced golf ball sized hail, and a weak F0 tornado. There was actually more damage caused by straight line winds, than the brief tornado. Remember, that straight line winds can be just as strong as most tornadoes. These winds downed numerous trees, some of which fell onto homes.
There were several days in June that had isolated severe thunderstorm events. June 11th saw the best coverage a thunderstorms. A nearly stationary frontal boundary stretched west to east across northern North Carolina into southwest Virginia. A couple episodes of severe thunderstorms happened the 11th. The early morning saw a small episode occur over far southwest Virginia into the North Carolina mountains and foothills. Generally this event produced isolated wind damage and large hail. More thunderstorms occurred in the afternoon east of the mountains. One severe thunderstorm downed numerous trees in Yadkinville.
The bigger weather story for June was the flooding episode that happened from the 25th through the 29th. A broad area of low pressure southeast of the Bahamas moved slowly northward over several days, keeping the area in a southeast flow of tropical air. In the meantime, a northern stream system was dropping into the midwest and had pushed a surface front into the Appalachians. This front was the focus for shower and thunderstorm development. The initial surge of tropical moisture into the area was on Sunday, the 25th, with a clear outflow boundary moving into the mountains and colliding with weaker boundaries. The thunderstorms generated from this outflow caused some flash flooding as early as Sunday morning. Behind this initial outflow, upslope showers with heavy rain developed along the Blue Ridge overnight Sunday into Monday morning. The forecast area then had several waves of showers and thunderstorms from Monday afternoon, the 26th into Tuesday evening, the 27th, before the tropical low moved far enough north near the Norfolk, VA area, for the back edge of the showers to clear our eastern piedmont counties Tuesday evening.
The flash flooding was pretty much confined to the foothills, west into the mountains the 25th and 26th, with flash flooding occurring in the piedmont on the 27th. Unfortunately, one fatality occurred on the 27th, in Alleghany County, Virginia, when a young girl was apparently swept into a drainage culvert near Dunlap Creek west of Covington.
The flash flooding transitioned into main stem river flooding. Large river flooding was confined primarily to the James River and along the upper Roanoke River. The worst flooding on the James apparently occurred at Buchanan and Bremo Bluff which both reached Moderate Flood Stage. Several businesses near the river in Buchanan were flooded.
Here is a list of rainfall amounts from our automated rain gauges from the entire episode.
Some flooding pictures can be found here, from Emergency Services Coordinator, Spencer Suter, of Botetourt County, VA.
July was a very active month as well. 12 of the 31 days in July saw severe thunderstorms affect our area. The two biggest events happened on July 4th and July 19th.
July 4th, clusters of storms developed in the southwest Virginia and southern West Virginia mountains early in the afternoon. They really took off along and east of the Blue Ridge after 4:00 pm edt, as they encountered more unstable air. The strongest storms occurred from Franklin County Virginia, southwest to Carroll County Virginia and Surry County North Carolina. Storms mainly produced damaging winds. The worst of the damage occurred near Burnt Chimney, Virginia, close to Smith Mountain Lake. Here, winds caused structural damage to decks, roofs, a chimney and 2 cars. There was also enough rainfall to cause flash flooding in the community of Cana, VA in Carroll County.
July 19th saw plenty of severe thunderstorms, mainly as a result of daytime heating, and residual boundaries from thunderstorms. The storms developed initially along a boundary in the piedmont near Charlotte County, and at the same time in the Greenbrier and Alleghany Highlands area from heating. Both of these boundaries seemed to merge across the New River and Roanoke Valleys during the late afternoon and early evening.
The worst of the storms occurred in Roanoke, where severe winds blew part of the roof off the Virginia Museum of Transportation.
Overall, August was a quieter month than June and July. There were 3 days of isolated severe weather episodes. The main weather event occurred at month's end.
A cold frontal boundary moved into the area on Wednesday, August 30th. The front produced 2-4 inches of rain across Southside Virginia Wednesday and Wednesday night. Flash flooding occurred in 5 counties. Severe weather was also a problem along the Virginia and North Carolina border, as storms mainly produced damaging winds, resulting in trees down. Rain was steady as the front drifted to the south and winds became easterly. Thursday, August 31st the remnants of Tropical Storm Ernesto moved north along the southeast coast. Tropical moisture moving into the area kept rain steady with only a few bands producing heavy downpours. Ernesto moved ashore Thursday evening near Wilmington, North Carolina. As Ernesto moved to the north and through the piedmont, rain bands in the piedmont were moderate to heavy at times overnight Thursday and into Friday morning, September 1st. By Friday evening, the remnants of Ernesto had caught up with the front and moved into the Chesapeake Bay area, cutting off the rainfall on the backside of it. We dodged a bullet with Ernesto, as the heaviest of the rains stayed east of us, preventing moderate flooding along the rivers east of the Blue Ridge.
The rest of September was fairly quiet, until the 28th. A strong storm system over the Mid-Mississippi and Ohio valleys brought a very strong cold front through the area during the best heating of the day. Organized severe thunderstorms developed and tracked across nearly all portions of the region. Widespread large hail with occasional wind damage occurred across many counties. The largest hail was the size of quarters, which fell in the city of Roanoke just after 4:00 PM EDT. Also winds blew shingles off a roof during this time in Roanoke. As the storms moved east of the Blue Ridge, they became more damaging wind producers. A tree was blown down in Rocky Mount and Ferrum in Franklin County, Virginia. Between 5:30 PM EDT and 6:30 PM EDT, the storms moved across southside Virginia and the northwest piedmont of North Carolina, downing trees and power lines.