UNC Study: Storms with heavy rainfall are the new normal

Hurricane Floyd in 1999.

Hurricane Matthew in 2016.

Hurricane Florence in 2018.

All caused significant damage due to flooding, and it's a trend a recent study from UNC shows could be caused by a changing climate.

"They all had one thing in common, and that is very high rainfall and extensive flooding, so we got interested in that and decided to explore the long-term dataset for North Carolina," said Hans Paerl, a professor at the UNC-Chapel Hill Institute of Marine Sciences in Morehead City.

The study looked at 120 years of weather data, most collected by the National Oceanic and Atmospheric Administration or NOAA.

"We were really struck by that data because 6 out of the 7 wettest storms datasets that have occurred over the 120 years occurred in the last 20 years," said Paerl.

"So we asked a question, are we just unlucky in North Carolina over the last 20 years or is this a real trend?"

The research team calculated the probability of the flooding happening by chance at 2%.

Paerl says it's more likely due to a changing climate, warmer oceans leading to more water vapor in the air.

It's a trend WRAL meteorologist Mike Maze has been noticing more often.

"There are discussions that come out from the weather service every day, and they talk about the chance for storms, but they also talk about the amount of moisture in the atmosphere, and I've seen more wording lately where they talk about record amounts of moisture in the atmosphere for this time of the year. So when fronts come along and access that moisture you may have bigger rain events," Maze said.

He also said it's a shift he's been recognizing during his 25 years forecasting weather in North Carolina.

"You can't help but notice there is a change going on. Is it solely man made? I'm not sure. Is it just a cycle that's going on? Could be, but there are more pieces of the puzzle that are coming together," Maze said.

"This is not a predictive study," Paerl said. "We are not predicting what's going to be down the line, although given what we now know it's difficult to assume we are not going to get some more of these high rainfall events."

Paerl said he was motivated to do this study because he lives near the cost and has experienced many of these storms.