Tornadoes and Derechos in Virginia

A "derecho" (Spanish for "straight") is a band of wind at the front of a storm. A June, 2012 a storm complex caused a derecho with 80 mile per hour winds that created havoc for 600 miles, as it moved from the Midwest to the Delmarva Peninsula. In Virginia, 15 people died, and trees falling on power lines caused the third-largest power outage in the state's history (exceeded only by hurricanes Isabel and Irene).1

Port City Brewing Company in Alexandria saved its 13,000 gallons of beer by allowing one batch to ferment at higher temperatures. The beer in process was supposed to be fermented at cool temperatures, but the brewery made steam beer (California common) instead of lager and labelled it "Derecho Common." A year later, an anniversary party at the brewery got an added dose of authenticity when there was a brief power outage, and the celebration required flashlights.2

the 2012 derecho knocked over trees and caused widespread power outages for a week after the storm
the 2012 derecho knocked over trees and caused widespread power outages for a week after the storm
Source: Virginia Derecho Blog, power outages as of July 5, 2012

The Peter's Mountain Roar in Giles County is a Spring phenomenon, sounding like "a tremendous thundering roar of giant waves breaking over rocky reefs." It is described as:3

originating in the Atlantic Ocean and traveling unabated across Virginia until striking Peter's Mountain, when it spills over the ridge causing the roar. Local residents have observed, here in the fields below, ocean gulls and wild geese which have been carried along the mighty current of air and, being exhausted and confused after topping the mountain, have come to rest.

the Peters Mountain Roar at the West Virginia border is caused by winds from the Atlantic Ocean
the Peters Mountain Roar at the West Virginia border is caused by winds from the Atlantic Ocean
Source: ESRI, ArcGIS Online

Tornadoes are tightly-concentrated, high-energy, violently rotating columns of air. Tornadoes appear and disappear quickly, usually within minutes. High winds without the rotation associated with tornadoes, usually in the mountains and along the coastline, offer a steady source of windpower energy.

Such winds may also be dangerous, like tornadoes. When the Blue Ridge is at the edge of high pressure systems from the north in January/February, and low-pressure systems are located to the southeast near the warmer ocean, the winter winds can flow through the gap at speeds up to 120 miles per hour. That is sufficient to rip the doors off of vehicles, overturn trucks, and even lift people into the air.

On January 24, 2003, five tractor-trailer trucks were flipped onto their sides on Interstate 77 at Fancy Gap. A state trooper who reported to the accident scene claimed he had to hold onto the guardrail to avoid being tossed over the edge of the roadbed that had been carved into the side of the mountain. Another said:4

The wind just took them over. They were just like those Matchbox trucks.

Virginia experiences 15-25 tornadoes annually, on average. Tornadoes can strike at any location in Virginia, and can vary dramatically in wind speed. A tornado with winds reaching 225 miles per hour blasted downtown Petersburg in 1993. A quick-forming July, 2014 tornado with winds around 100 miles per hour knocked trees onto tents and recreational vehicles at a campground filled with 1,300 people near Cape Charles on the Eastern Shore. Two campers were killed, and 36 others injured.5

Tornadioes occur in the ruggest mountains, as well as on the more-open Piedmont and Coastal Plain physiographic provinces. The most devastating tornado to hit Virginia - so far - was in 1929 in Scott County's Rye Cove. The two-story wooden school building was demolished. Of the 150 people inside just after recess, 13 were killed (including one teacher) and 56 injured.

Virginia's most-deadly tornado killed 12 students and one teacher at Rye Cove in 1929
Virginia's most-deadly tornado killed 12 students and one teacher at Rye Cove in 1929
Source: ESRI, ArcGIS Online

Links

References

1. "2012-06-29 Severe Weather Situation Report #19," Virginia Emergency Operations Center, July 21, 2012, http://www.vaemergency.gov/webfm_send/487/VERTSitRep19-21July2012.pdf (last checked July 26, 2014)
2. "Port City Celebrates Derecho Anniversary With Derecho Beer Re-Release; Promptly Loses Power Again," DCist, June 28, 2013, http://dcist.com/2013/06/port_city_celebrates_derecho_annive.php; "Port City Names Beer After Storm That Helped Create It," DCist, July 9, 2012, http://dcist.com/2012/07/no_beer_left_behind_port_city_brewe.php (last checked July 26, 2014)
3. "Peter's Mountain Roar," Hanging Rock Raptor Observatory, http://www.hangingrocktower.org/roar.htm (last checked July 26, 2014)
4. Gangloff, Mike, "Wintry blasts topple trucks on I-77," The Roanoke Times, January 25, 2003, www.roanoke.com/roatimes/news/story143458.html (last checked January 25, 2003)
5. "Storm cut path of random ruin; officials tour camp," The Virginian-Pilot, July 26, 2014, http://hamptonroads.com/node/723491; "Tornado History," Virginia Department of Emergency Management, http://www.vaemergency.gov/news/history/tornado (last checked July 26, 2014)
6. "Rye Cove Cyclone," Virginia Encyclopedia, http://www.encyclopediavirginia.org/Rye_Cove_Cyclone (last checked July 26, 2014)

Virginia experiences a derecho once every four years, on average
Virginia experiences a derecho once every four years, on average
Source: National Oceanic and Atmospheric Administration (NOAA), About Derechos


Climate
Virginia Places