Tornadoes and Derechos in Virginia

tornadoes knock down trees in the forest and houses in the suburbs
tornadoes knock down trees in the forest and houses in the suburbs
Source: U.S. National Archives, Suffolk, VA, 4/30/08 (by Liz Roll/FEMA)

Multiple locations in Virginia have been identified with consistently higher-than-average winds. Those sites are in the mountains and along the coastline, and are the preferred locations for building wind turbines to generate electricity. Tornadoes offer the greatest concentration of windpower energy in Virginia, but their locations can no be predicted and their energy can not be harvested by wind turbines.

Tornadoes are tightly-concentrated, high-energy, violently rotating columns of air. Tornadoes appear and disappear quickly, usually within minutes, and move across the surface of the earth in unpredictable paths. Some are spawned by hurricanes moving west from the Atlantic Ocean or north from the Gulf Coast. Others spin out of strong storms that typically move east across the continent into Virginia.

Tornadoes occur in the Appalachian mountains and on the Blue Ridge, as well as on the more-open Piedmont and Coastal Plain physiographic provinces. Between 1991-2010, on average Virginia experienced 18 tornadoes annually.1

Virginia experiences only 1% of the tornadoes that touch down in the United States each year, on average
Virginia experiences only 1% of the tornadoes that touch down in the United States each year, on average
Source: National Oceanic and Atmospheric Administration (NOAA), Historical Records and Trends

Tornadoes are classified by wind speeds which are correlated to their effects on the ground, particularly on human-built structures. The original Fujita Scale was "enhanced" in 2007 to align wind speeds with property damage more closely.

Only the National Weather Service determines if a wind event was a tornado and can assign an official tornado Enhanced Fujita Scale rating. EF ratings are based on after-the-fact estimates of wind speed based on the visible effects on structures, rather than actual measurements by scientific instruments or sensors. Where tornadoes cross open fields, damage is particularly hard to estimate. A 2021 study using Doppler radar measurements suggested that the National Weather Service has underestimated the power of such tornadoes, with ratings 1.2 to 1.5 categories too low.2

tornadoes knock down trees in the forest and houses in the suburbs
tornadoes knock down trees in the forest and houses in the suburbs
Source: National Weather Service, January 13 2013 EF0 Eagleville Tornado

Tornadoes can kill people as well as destroy property at any location in Virginia. Between 1950-1994, the 279 tornadoes recorded in Virginia killed 25 people. Though Virginia has only 1% of the tornadoes that touch down in the United States each year, on average, it is in the middle of the 50 states for number of tornadoes causing fatalities and the total number of deaths.

Tornadoes peak in April and again in September, when hurricanes are likely to strike Virginia. Most strike in the afternoon, when the sun has heated the atmosphere and instability is greatr.

Less than 20% of the tornadoes in Virginia are rated as EF-2 or higher on the Enhanced Fujita Scale, but the most powerful storms cause roughhly 80% of the property damage and injuries and almost 90% of the fatalities. The less-intense EF-o tornadoes touch down only briefly, with a track on the ground averaging 1.7 miles. The EF-2 tornadoes stay on the ground for an average of five miles, while EF-3 tornadoes touch down for an average of 10 miles. As a result, EF-2 and stronger tornadoes have a greater opportunity to encouter structures as well as more power to demolish buildings.3

tornado paths between 1950-2019
tornado paths between 1950-2019
Source: Storm Prediction Center, National Weather Service, SVRGIS

Though news stories often highlight the highly-visible damage to rural trailer homes, cities are not immune. 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.4

The deadliest tornado to hit Virginia, so far, was in 1929 in Scott County's Rye Cove. The two-story wooden school building, with eight rooms and an auditorium, was demolished. Of the 150 people at the Rye Cove Consolidated School just as recess ended, 56 were injured. Of the 13 who were killed, 12 were students and one was a teacher. Her body was carried 75 yards away as the building was smashed by the powerful wind.

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: Newspapers.com, The Springfield Press (May 4, 1929)

According to one teacher, there was no time to seek cover and "the building collapsed with a smash" as soon as the storm hit. The school principal described how the tornado was a complete surprise:5

As it neared the school building it became a black cloud... I think I yelled. It struck the building. The next thing I remembered I was standing knee deep in a pond 75 feet from where the building stood before it was demolished.

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

One of the rescuers, A. P. Carter, composed a song about what he saw with the lyric:6

Oh listen today and a story I tell
With saddened and tear dimmed eyes
Of a dreadful cyclone that came this way
And blew our schoolhouse away.


Source: You Tube, The Cyclone Of Rye Cove Carter Family

In addition to a spinning tornado, strong winds may also be dangerous. 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:7

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

Any spot in Virginia can experience a "derecho." 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. Trees falling on power lines caused the third-largest power outage in the state's history (exceeded only by hurricanes Isabel and Irene), and led to a move to place distribution lines underground in the most outage prone areas.8

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

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.9

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:10

...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.

Hurricanes in Virginia

Wind Energy in Virginia

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

Links

shade trees next to houses can become projectiles and bludgeons in a tornado
shade trees next to houses can become projectiles and bludgeons in a tornado
Source: Flickr, Bedford County Virginia Tornado Damage April 2002 (by Kipp Teague)

tornado winds lift roofs off structures without hurricane roof clips
tornado winds lift roofs off structures without hurricane roof clips
Source: Flickr, Bedford County Virginia Tornado Damage April 2002 (by Kipp Teague)

References

1. "Average Annual and Monthly Numbers of Tornadoes by State - Maps," National Oceanic and Atmospheric Administration (NOAA), https://www.climate.gov/maps-data/dataset/average-annual-and-monthly-numbers-tornadoes-state-maps (last checked March 18, 2021)
2. "The Enhanced Fujita Scale (EF Scale)," National Weather Service, https://www.weather.gov/oun/efscale; "We’re underestimating the destructive power of tornadoes, study shows," Washington Post, March 22, 2021, https://www.washingtonpost.com/weather/2021/03/22/tornado-power-underestimated-study/ (last checked March 23, 2021)
3. "Tornado Numbers, Deaths, Injuries, and Adjusted Damage, 1950-1994," National Severe Storms Laboratory, National Oceanic and Atmospheric Administration (NOAA), http://www.spc.noaa.gov/archive/tornadoes/st-trank.html; "Historical Records and Trends," National Centers for Environmental Information, National Oceanic and Atmospheric Administration (NOAA), https://www.ncdc.noaa.gov/climate-information/extreme-events/us-tornado-climatology/trends; "Worst-case weather: a closer look at when and where the strongest tornadoes hit Va.," Richmond Times-Dispatch, March 16, 2021, https://richmond.com/weather/worst-case-weather-a-closer-look-at-when-and-where-the-strongest-tornadoes-hit-va/article_b30550a2-acdc-5ae6-a5c8-68e6b1fe6491.html (last checked March 18, 2021)
4. "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)
5. "Rye Cove Cyclone," Virginia Encyclopedia, http://www.encyclopediavirginia.org/Rye_Cove_Cyclone; "'Blew our schoolhouse away' - Duffield, Virginia," Southern Spirit Guide, November 5, 2014, http://www.southernspiritguide.org/blew-our-schoolhouse-away-duffield-virginia/ (last checked March 18, 2021)
6. "A dreadful cyclone that came this way," AppalachianHistory.net, May 2, 2019, https://www.appalachianhistory.net/2019/05/dreadful-cyclone-that-came-this-way.html (last checked March 18, 2021)
7. 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)
8. "Dominion Energy looks back on 2012 derecho," WHSV, June 29, 2017, https://www.whsv.com/content/news/Dominion-Energy-looks-back-on-2012-derecho--431676093.html (last checked March 18, 2021)
9. "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)
10. "Peter's Mountain Roar," Hanging Rock Raptor Observatory, http://www.hangingrocktower.org/roar.htm (last checked July 26, 2014)
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)

most tornadoes strike in the Great Plains or near the Gulf Coast
most tornadoes strike in the Great Plains or near the Gulf Coast
Source: Storm Prediction Center WCM Page, National Weather Service, Tornado Climatology -- All Tornadoes


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