North Carolina will see more extreme rain events in the future

Extreme rainfall events are happening more often in North Carolina, according to presentations from the N.C. Institute for Climate Studies and projections from First Street Foundation.

Why it matters: Such severe weather can lead to flash flooding and create infrastructure issues — especially as leaders build out plans for what communities will look like decades from now.

• As the state continues to urbanize, even smaller amounts of rain can cause flooding risks due to increased surface runoff, said Gary Lackmann, an N.C. State professor who studies high-impact weather systems.

By the numbers: 2018 was North Carolina's wettest year on record, thanks to Hurricane Florence, which flooded Interstate 40 and turned Wilmington into an island.

• But it's more than hurricanes. Between 2015 and 2018, the state saw its largest number of heavy precipitation events in a five-year period, according to NCICS, even though that included just four years.

What's happening: It's "virtually certain" the amount of water vapor over North Carolina is rising, due to increased ocean and atmospheric temperatures driven by global warming, according to NCICS.

• More available water vapor leads to more intense and frequent rainfall events, said Kathie Dello, director of the North Carolina State Climate Office.
• Often, she said, these events impact low-income and minority populations. Princeville, the first town chartered by Black people in the U.S., has a history of major floods because of where its residents were forced to settle.

What's next: Lackmann said he and a team of N.C. State scientists are working directly with the state’s Department of Transportation on ways to make the state more resilient to these types of events.

• "When you do something like raise the I-95 Bridge at Lumberton, you don't want to have to do that again in 20 or 50 years," he said. "It's expensive, and so you want to raise it as much as you need to the first time."
• The state's 2021 budget included money to help local governments pay for resiliency projects and fund land conservation around waterways, The News & Observer previously reported. Wake County is currently creating three new nature preserves.

Zoom in: The town of Cary is currently testing out how it can use technology to make it more responsive to flooding from water runoff.

• It’s working with local analytics giant SAS Institute to put stormwater sensors throughout the town to predict where flooding could occur and improve responses to it.

Bottom line: North Carolina and its cities will need to become more proactive when it comes to managing extreme-rainfall events.

• "There are places that we know are trouble spots," like Crabtree Creek in Raleigh, Lackmann said. "But what we want to avoid are more of those spots cropping up in the coming years."