For the third consecutive year, a wave of water gushed out of an Alaskan glacial lake, threatening the state’s capital city of Juneau. But, flood barriers installed by the city managed to prevent disaster from unfolding in the picturesque port town despite record-breaking water levels this week.

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

Officials in recent days have been warning people in the flood zone to be ready to evacuate. On Tuesday morning they confirmed water had started escaping the ice dam, with flooding expected late Tuesday and on Wednesday.

Alaska Gov. Mike Dunleavy declared a state disaster due to the "imminent threat of catastrophic flooding from a glacier lake outburst flood" in the Juneau area.

Residents in some parts of Juneau prepared to evacuate ahead of what could be a record surge of flooding as rainwater and snowmelt in a huge basin dammed by Alaska’s Mendenhall Glacier

The National Weather Service has issued a warning as glacial water flows into the Mendenhall River.