As Hurricane Irma’s expected path arcs westward, Raleigh and the rest of central North Carolina might avoid the worst of the storm.
But the National Weather Service predicts Raleigh will see between 1 and 3 inches of rain Monday and Tuesday. That could be cause for concern for those who live and travel near Crabtree and Walnut Creeks, two areas of the city that often flood from storms less feared than Irma.
“It’s all dependent on how quickly we get that 1 to 3 inches,” Raleigh stormwater engineer Ben Brown said. “That’s why these summer thunderstorms can become larger events, when no one thought that was going to happen. It could be 1 to 2 inches, but because it happened in half an hour, it’s a problem.
“If the storm sits on us, we could get a lot more rain over a longer period of time, and that could be a big problem too,” he added.
Raleigh posted an advisory online Thursday saying “inland flooding remains the largest threat to life during land-falling hurricanes in central (North Carolina).”
Crabtree Valley Mall near Glenwood Avenue and the Interstate 440 Beltline lies in a floodplain and has been particularly vulnerable to flooding. In past deluges, the mall has had to close as portions of Creedmoor Road and surrounding parking lots have been submerged.
Part of Wake Forest Road near Six Forks Road flooded last April when a three-day storm dumped 6 to 9 inches of rain on the Triangle.
Spread over two days, a few inches of rain shouldn’t rise to the level of the damaging floods that occurred last spring or in the wake of Hurricane Matthew last fall. But waters could still rise.
“Heavy rain from Hurricane Irma is likely to cause Crabtree Creek and Walnut Creek to overflow in the floodplain, because the creeks reach capacity and cannot handle large amounts of rain in a short period of time,” Brown said.
The Crabtree Creek floodplain mostly follows the south side of I-440, though a branch extends south down Capital Boulevard as far as Peace Street.
Walnut Creek’s floodplain is narrower and roughly follows the north side of Interstate 40.
Most construction was restricted in floodplains after the 1970s, but older homes and other structures remain in vulnerable areas.
Residents can check whether their homes or businesses lie in a floodplain by going to https://maps.raleighnc.gov/iMAPS/ and clicking the “Floodplains” layer.
Gargan: 919-829-4807; @hgargan