Just one week after the Super Derecho of late June 2012 impacted millions of people across the Upper Midwest and Mid-Atlantic region, an intense localized microburst impacted part of the Fredericksburg, Virginia area, around 60 miles south of Washington, D.C. The microburst caused considerable property damage and several injuries on the evening of July 8, 2012.

The NWS post-storm summary told the story of a microburst with an estimated 80 mph peak wind speed that impacted an approximately three-mile swath on the southern end of the city of Fredericksburg. A roof was torn off of a gymnasium and one of the walls collapsed. Seven people reported injuries as a result from the damage to the gym. The roof from the gym was displaced and thrown onto a residence next to the gym. Other nearby buildings received roof damage and the intense winds snapped or unrooted dozens of trees in the area. A number of residences in the adjacent subdivision were damaged by fallen trees.

Microbursts are caused by the downrush of air initiated by a thunderstorm that induces an outburst of damaging straight-line winds on or near the ground. Downburst winds can produce damage similar to an EF0 or EF1 tornado, on the order of 80 to 100 mph winds in some  instances. Microbursts are characterized by an affected outflow area of less than 2.5 miles and peak winds lasting less than five minutes. In addition to property damage, microbursts were responsible for several deadly aircraft accidents in the 1970s and 80s, before the advent of Terminal Doppler Weather Radar helped in their identification near airports.

Crystal Seal, hairstylist and owner of Set-N-Trendz Salon in Fredericksburg, experienced the power of this microburst firsthand when it blew the roof off her business and also burying her SUV. “(My daughter) and I were in the salon ... we ran to the color bar/kitchen right before the roof caved in and destroyed the entire front area,” Seal said. Fortunately, no one was hurt, but her business needed to be relocated temporarily while she rebuilt.

Severe Thunderstorm Warnings issued by the NWS convey the threat of damaging winds, possible tornadoes and large hail. This is another reason that it is always a good idea to find an interior room in the lowest part of a strong building and shelter-in-place when a Severe Thunderstorm Warning is issued. 

Resources and Additional Reading

• Article: What is a Microburst? https://www.weather.gov/bmx/outreach_microbursts#

• Learn More About Microbursts and Other Weather Phenomena at JetStream Online School for Weather: https://www.weather.gov/jetstream/

• Severe Thunderstorm Safety: https://www.weather.gov/safety/thunderstorm