St. Louis, Death Valley and now Dallas: Why '1,000-year' floods suddenly seem so common

Dallas has joined four other U.S. communities that have recently experienced hot — and then suddenly much too wet — summers.

Dallas has joined four other U.S. communities that have recently experienced hot — and then suddenly much too wet — summers.

Extreme rainfall hammered the Dallas area Monday, killing at least one person, requiring hundreds of rescues and adding the city to a list of communities in the nation that saw precipitation so intense that it was expected just once in a millennium. 

Some parts of Dallas saw more than 13 inches of precipitation in 12 hours, according to the city’s water utility — enough to exceed the marker set by the National Oceanic and Atmospheric Administration for a 1-in-1,000-year precipitation event. 

Elsewhere, heavy rainfall left 37 people dead in eastern Kentucky, closed all roadways in the Death Valley National Park near the California-Nevada border, forced rescues in suburban St. Louis and sent vehicles into ditches in southern Illinois. Each of these storms has been described as a 1-in-1,000-year event, meaning that each year, there is a .1% chance it could happen, based on historical data. 

But climate researchers say a warmer atmosphere has juiced the potential for extreme rainfall and damaging flooding. Although it’s difficult for scientists to immediately interpret the link between a single weather event — or string of events — and climate change, human-caused warming has rapidly shifted the probability of extremes so much that some of them say these numbers are losing their relevance as benchmarks because they’re changing so fast. 

https://www.nbcnews.com/science/environment/floods-dallas-climate-rcna44279

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