Why a 1-in-1,000-year rain event devastated Ellicott City, Maryland — again

By John Bacon, USA TODAY

Flash flooding caused by heavy rain falling in a short amount of time.
By Kingbob86 (Timothy) • CC BY 2.0


Blame it on the rain. And the topography. But global warming? Maybe not so much.

Residents and business owners in historic Ellicott City were picking up the pieces Monday after the second “1-in-1,000-year” rain event in two years walloped the Maryland town on the banks of the Patapsco River. More than eight inches Sunday triggered flash flooding that sent a wall of water down Main Street, reaching the second floor of some buildings and sweeping cars into culverts.

Two years ago, 6.5 inches of rain fell on Ellicott City in about 3 hours, with 5.5 inches falling in just 90 minutes, the National Weather Service said. That was dubbed a 1-in-1,000-year rain event.

AccuWeather Meteorologist Brian Lada stood by the statistics. The odds reflect the chance of the heavy rains, not necessarily flooding, he added.

“It’s a really rare event that just so happened to occur two years apart,” Lada told USA TODAY. “That 1-in-1,000 doesn’t take into account the topography of the area.”

The town was defenseless for Sunday’s precipitation onslaught, he said. Four creeks converge on the town enroute to the Patapsco. There was no place for the water to go.

“The worst flooding was Main Street, which is all concrete, so it flowed right through,” Lada said.

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