2012 Derecho
The June 29-30, 2012 derecho was one of the deadliest and most destructive of its kind in U.S. history.
Introduction and Event Overview
On June 29, 2012, a single storm developed in Iowa around noon and produced the day's first damaging wind report just before 1 PM. Very hot and unstable air south of a stationary front provided fuel, allowing that single storm to grow into a Mesoscale Convective System (MCS) which matured into an extremely damaging Derecho, spanning much of the Midwest and the Mid-Atlantic states over the course of the next 12 hours. A total of 1,195 individual reports of wind damage occurred, across Illinois, Indiana, Ohio, West Virginia, Virginia, and northern North Carolina. The system only stopped producing damage when it moved offshore into the Atlantic Ocean around 2 AM on the 30th, but likely continued to impact mariners. There were many injuries and 34 deaths nationwide, not only from the winds themselves, but also from heat-related illnesses in areas where power was knocked out by the derecho. In the NWS Blacksburg area, at least one heat related fatality was recorded.
While derecho wind storms are most common in the upper Midwest, and do on rare occasion reach the Appalachians and cross into the Piedmont and Atlantic Coastal regions, the last one to begin to compare with the June 2012 event occurred in August of 2000. The June 29 event, however, was more extreme than any in recent memory for this region, in part due to the magnitude of the maximum winds (over 80 mph in many cases) and also because it was so expansive. The airmass that helped this system sustain its intensity for so long was very unusual, with extreme heat at the surface and what is known as an “elevated mixed layer” (EML) just above the surface, created extremely unstable, yet relatively dry, conditions. The fact that the derecho remained intact as it crossed the Appalachians is a climatological rarity.
In fact, the heat continued to be a significant concern with this derecho because of the widespread power outages it caused. A heat wave that was building in the days leading up to the derecho continued for about a week after the event. More people died because of the heat in the days following the storm than from the derecho itself: 34 versus 13. Several National Weather Service Forecast Offices lowered their heat advisory criteria in the areas hit hard by power outages by as much as 10F in order to issue heat related headlines.
The June 29-30th, 2012 Derecho By the Numbers
- Length...over 700 miles
- Direct Deaths...13, mainly from falling trees
- Indirect Deaths...34, mainly from heat-related illnesses
- Estimated without Power...4 million
Synopsis and Initial Conditions
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1
Watch Issued
Severe Thunderstorm Watch 438 was issued by the Storm Prediction Center at 6:35pm EDT for a large portion of the southern Mid-Atlantic. The Storm Prediction Center gave high probabilities for wind damage within this watch.
Probability of 10 or more severe wind events - High (>95%)
Probability of 1 or more wind events > 65 knots - High (70%)
2
The 1st Warning
Issued at 7:49 PM EDT for Greenbrier, Mercer, Monroe, and Summers County. Winds in excess of 80 mph with a history of producing widespread wind damage in central West Virginia.
Numerous trees were reported down across all southeast West Virginia counties, along with structural damage and roofs partially removed from buildings.
3
STRUCTURES DAMAGED
As 70-80 mph + wind gusts plowed through neighborhoods like a bulldozer. Trees and powerlines were thrown all over place including here in New Castle, Virginia. Photo source via Kevin Myatt of the Roanoke Times.
4
High Winds
As the derecho pushed farther east into the heart of the Blue Ridge region, many cities including Roanoke measured wind gusts upwards of 80 mph. These gusts are equivalent to an EF-1 tornado or Category 1 hurricane. Image credit to Iowa State University - Iowa Environmental Mesonet Website.
5
MASSIVE TREES TOPPLED
Gusts upwards of 70-80 mph + toppled trees and powerlines all across the city of Roanoke. Photo source via Kevin Myatt of the Roanoke Times. Location: Old Southwest section of Roanoke, Virginia.
6
PICKING UP THE PIECES
Many neighborhoods around our region looked like this one. Swaths of trees and powerlines snapped for miles in the wake of 70-80 mph+ winds from the derecho. Many endured temps well into the 90s and even triple figures in the wake of the event making recovery and cleanup even harder. Photo source via NWS Blacksburg.
7
Injuries
At least 17 injuries were reported across our region, including 12 in the Fincastle, VA area. Other areas with injuries included Danville, Lexington, and Boones Mill, VA. Image credit to Iowa State University - Iowa Environmental Mesonet Website.
8
Direct Fatality
Along with the 17 injuries, sadly a direct fatality also occurred. A firefighter in Franklin county was on their way to the station and had stopped to help another driver who's car had been hit by a tree. While trying to assist the driver, another tree fell on him. Photo source via WSET.
9
Wind Damage
Trees and powerlines were toppled in nearly every town and community from West Virginia to North Carolina. Widespread structural damage was also reported, along with power outages that lasted in some cases more than a week. Image Credit to Iowa State University - Iowa Environmental Mesonet Website
10
THE DAMAGE SWATH CONTINUES EAST
Here's the view from Lynchburg, Virginia once the derecho passed. Numerous reports of damage across the Montview, Bedford Hills, Fairview Heights, and Tate Springs area of town.
11
The Last Warning
The last warning of the event from WFO Blacksburg was issued at 10:43 PM EDT for Rockingham and Caswell Counties in the North Carolina Piedmont. Image Credit to Iowa State University - Iowa Environmental Mesonet Website.
The following images also show another indication of the “mark” left by these extreme winds, which caused a total of over 4 million customers to lose power. These are nighttime NASA satellite images of before (left) and after (right) showing indications of where power was lost across parts of WV and VA (especially in the smaller towns and more rural areas). Slider photo credit to National Aeronautics and Space Agency Earth Observatory.
June 28 (before derecho) June 30 (after derecho)
Noted below by the image: a vast majority of counties in the NWS Blacksburg forecast area in Virginia saw as much as 20% - 60% of the county's customers without power, with some counties seeing as much as 80% - 100%. Nearly half of all Virginia residents are estimated to have lost power from this event. Image source from the Virginia Department of Emergency Management.
In the days following the derecho, much of the nation experienced a heat wave, as can be seen in these images of temperature anomaly on June 30 and July 1, 2012. Southwest VA and northwest NC were experienced temperatures 6°-10° Celsius (11°-18° Fahrenheit) hotter than average. Below the temperature anomaly images, you will see maps that show temperatures recorded at a collection of sites maintained by the National Weather Service in Blacksburg. Many were without electricity due to damage caused by the derecho, further imperiling lives in the heat wave.
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Damage from the derecho in Lynchburg, VA as surveyed by the NWS and Lynchburg Department of Emergency Services.
After Action Review and Policy Changes
The 2012 derecho caused the National Weather Service to implement new changes, which included new forecaster training and new wording of warnings. One of those changes was to to look into using impact-based wording, which is used today in severe warnings across the National Weather Service. Another current policy that is used today that came as a recommendation from the 2012 event was the use of agency-wide threat tags and the National Weather Service could then leverage those tags to trigger WEA (wireless emergency alerts) for extreme events to better alert the public. You can read the full service assessment report HERE .
