5 Years Ago: The June 2012 Derecho

Posted: June 22, 2017, 10:38 am by abarney

When called upon to remember a significant weather event within the last 10 years or so, some may bring up a powerful snow storm or blizzard. But for those that were within the path of the June 29, 2012 Derecho, the case is a bit different as that system was one of the top (if not the top) memorable events within the last 15 years or so.  This straight-line windstorm, which occurred in the middle of a record heat wave, left millions without power and caused widespread property damage to areas within its path. Here's an idea of what a derecho is: 

Derecho: A widespread, long-lived, and violent convectively-induced straight-line windstorm. It is a type of mesoscale convective system (MCS), and is associated with a fast moving band of severe thunderstorms that usually takes the form of a bow echo. To be classified as a derecho, this MCS must have a swath of damaging winds over 58 mph for at least 250 miles. 

A composite image of radar reflectivity by hour of the June 29, 2012 derecho. Selected wind gusts are plotted. (Image courtesy Greg Carbin / NOAA / SPC)

The system developed on one of the hottest days of 2012, where high temperatures warmed well into the 90s and even into the 100s in some spots. This powerful complex roared through the Ohio Valley and began its trek through the mid-Atlantic states through the afternoon and evening hours. Along the way, wind gusts of up to 87 mph were reported in some spots, though over the entire area, wind gusts of 55-75 mph were more common. 

Damaging straight-line wind gusts were powerful enough to cause power outages for over 4 million customers. Many trees and powerlines were downed across the area, and the storm is responsible for 22 deaths. Many of those deaths were caused by falling trees.  Overall, around $2.9 billion in damage was caused by the derecho. As one of the more powerful complexes in recorded history, this will live on in the minds of those affected for quite some time. In fact, because it occurred during a heat wave, the ensuing days after the storm and during cleanup made things that much more difficult for those that were affected. It is not common to see such a long-lasting, powerful system maintain itself for as long as this derecho did, so hopefully the next one is a long way off. 

Infrared satellite loop, which clearly shows the June 29, 2012 derecho moving through the mid-Atlantic states. 

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