Virginia Gov. Robert F. McDonnell declared a state of emergency today and authorized the National Guard to assist with clearing trees and directing traffic in the Washington DC area, following last night’s sudden and violent storm. The storm in the DC area on June 29, 2012 – which occurred between 9:30 and 11 p.m. local time, following a day of recording breaking triple digit temperatures in the DC area – killed at least five people, uprooted thousands of trees and left more than 1.3 million homes and businesses without power in Maryland, Northern Virginia and Washington DC.
Temperatures in the Washington DC area “made history and toppled old records” on Friday, June 29, according to the Washington Post. The Post’s Capital Weather Gang today called the June 29 storm, which packed wind gusts of 60 to 80 miles per hour:
… one of the most destructive complexes of thunderstorms in memory.
The storm appears to have been caused by a derecho, which is a violent storm system that can produce widespread wind damage across a large area and is associated with a band of rapidly moving band of showers and thunderstorms. Another violent derecho appears to have occurred on June 11, 2012, affecting parts of Missouri, Tennessee, Kentucky, Arkansas, Mississippi, and Alabama. What you need to know about derechos.
According to the Washington Post, Gov. McDonnell said the storm triggered:
… Virginia’s largest non-hurricane power outage in history and forced the closure of 250 secondary and rural roads because of fallen trees.
The DC region is still under an excessive heat warning from the National Weather Service on Saturday (June 30). Libraries and swimming pools in the DC region have been opened today to give residents without power escapes from the heat,
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.