Glacial outburst floods aren't a new phenomenon in Alaska, but climate change is scrambling the geography of risk.

Sections of Alaska’s capital city are bracing for the arrival of what could be record floodwaters due to rainwater and snowmelt flowing downstream from a basin dammed by the Mendenhall Glacier.

Update, 6:25 a.m. Wednesday: The Mendenhall River hit a record level as of 6 a.m., according to the National Weather Service. The river is in major flood stage at 16.17 feet and rising, the agency said. That surpasses the record set last year of 15.99 feet.