The first named storm of the hurricane season weakened Wednesday night, but forecasters warned that it still posed a threat of massive amounts of rain and continued flash flooding.

Zachary Handlos, an atmospheric scientist at the Georgia Institute of Technology, said the potential for flash flooding will be determined by how quickly Tropical Storm Arthur moves through the region.

“What it comes down to is, is the rainfall going to park itself or become stationary over any of these locations?” Handlos said. “That is a little harder to predict.”