Capital Weather Gang

WEATHER

Here’s what caused Saturday’s destructive storms in the D.C. area

The extreme winds were not caused by a tornado or a derecho, but by what’s known as downbursts

By Jason Samenow, Jeff Halverson and Dan Stillman
July 30, 2023 at 6:00 a.m. EDT



A downed tree blocks the street Saturday in the 2400 block of Tunlaw Road NW in Washington. (Moira Haney/The Washington Post)

The violent storms that swept across the D.C. area Saturday afternoon and evening, that worst in more than a decade for some, were sparked by extreme heat and humidity, a strong cold front, and a vigorous disturbance high in the atmosphere.

Producing winds over 80 mph, the storms toppled trees onto buildings and cars, dislodged chimneys, tore down signs, peeled off roofs and cut power to more than 200,000 customers. Sections of Arlington and Northwest Washington, where thousands remain without power, were among the hardest hit.

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The storms that blasted the region didn’t contain tornadoes nor was there a derecho, which is a long-lived and large complex that often stretches across multiple states. Saturday’s storms were much more localized. But their winds were just as strong and the damage as devastating in some areas as those produced by some tornadoes and derechos.

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The source of Saturday’s fierce winds was a phenomenon known as downbursts. They are common in summer storms and are simply blasts of wind that originate in the clouds and then slam into the ground and fan out. They can produce gusts more severe than low-end tornadoes and are, by far, the most frequent source of violent winds in D.C.-area storms.

Very localized downbursts — affecting parts of neighborhoods — are frequently called microbursts, whereas larger ones — that can cover miles — are referred to as macrobursts. Saturday’s storms may have contained both types.

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By Jason Samenow
Jason Samenow is The Washington Post’s weather editor and Capital Weather Gang's chief meteorologist. He earned a master's degree in atmospheric science and spent 10 years as a climate change science analyst for the U.S. government. He holds the Digital Seal of Approval from the National Weather Association. Twitter https://twitter.com/capitalweather

By Jeffrey Halverson
Jeffrey Halverson, a contributor to The Washington Post’s Capital Weather Gang, teaches meteorology at the University of Maryland Baltimore County.

By Dan Stillman
Dan Stillman is a meteorologist and editor for the Capital Weather Gang. He earned an M.S. in Meteorology from Texas A&M University, and a B.S. in Atmospheric, Oceanic and Space Sciences from the University of Michigan. Twitter https://twitter.com/stillmand