Harvey, once in a millenium

Hurricane Harvey pounded southeast Texas for days and flooded homes and streets, and many forecasters and residents claimed they had never seen rain like this. 

Well, they were right. An analysis from the University of Wisconsin's Space Science and Engineering Center claims Harvey is a once in a millennium event, based on a Thursday story in the Washington Post. 

Shane Hubbard is the researcher who came to this conclusion. 

THE LATEST: Recovery efforts, other developments in Harvey's wake

"In looking at many of these events [in the United States], I've never seen anything of this magnitude or size," said Hubbard  "This is something that hasn't happened in our modern era of observations."

The chance of a storm like Harvey happening in any year is 0.1 percent, Hubbard said. 

"Or, a better way to think about it is that 99.9 percent of the time, such an event will never happen," Hubbard said.

Based on Hubbard's calculations, at least 20 inches of rain fell over an area larger than 10 states, including West Virginia and Maryland.

Additionally, at least 30 inches of rain fell over an area equal tot he size of Maryland. 

Some academics and flood planners are skeptical of the concept of a 1,000 year flood.

This is because flood data only goes back about 100 years or so. Additionally, climate change may make rare rain events, such as a 500-year flood,  more common.