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 started to flow downstream toward the capital city.
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. They advised people in the city's flood zone to leave.
One couple said they're encouraging their neighbors to evacuate, but plan to stay put after sending their kids outside the flood zone. Their three daughters, aged 11, 10, and 8, were sent to a friend's house at higher ground Tuesday to make absolutely sure they're safe.
"The girls are having sleepovers outside the flood zone," said Sam Hatch, a civilian Coast Guard vessel safety regulator. "A friend from work has three daughters as well so we shoved them all in one house and they're having a six-girl epic four-day right-before-school-starts sleepover. I really owe my friend for taking them."
The Mendenhall Glacier is about 12 miles (19 kilometers) from Juneau and is a popular tourist attraction due to its proximity to Alaska's capital city and easy access on walking trails. Homes on the city's outskirts are within miles of Mendenhall Lake, which sits below the glacier, and many front the Mendenhall River.
The water that's being released in the glacial outburst is flowing into the river, putting homes that are closest to the river at risk. The National Weather Service said it expected flooding to peak at 4 p.m. local time Wednesday.
"This will be a new record, based on all of the information that we have," Nicole Ferrin, a weather service meteorologist, told a news conference Tuesday.
Flooding from the basin has become an annual concern, and in recent years has swept away houses and swamped hundreds of homes. Government agencies installed temporary barriers this year in hopes of protecting several hundred homes in the inundation area from widespread damage.
The thinning, retreating glacier in southeast Alaska acts as a dam for Suicide Basin, which fills each spring and summer with rainwater and snowmelt. The basin itself was left behind when a smaller glacier nearby retreated.
When the water in the basin builds up enough pressure, it forces its way under or around the ice dam, entering Mendenhall Lake and eventually the Mendenhall River.
Before the basin reached the limit of its capacity and began overtopping, the water level was rising rapidly -- as much as 4 feet per day during especially sunny or rainy days, according to the National Weather Service.
Last year, nearly 300 residences were damaged.
A large outburst can release some 15 billion gallons of water, according to the University of Alaska Southeast and Alaska Climate Adaptation Science Center. That's the equivalent of nearly 23,000 Olympic-size swimming pools. During last year's flood, the flow rate in the rushing Mendenhall River was about half that of Niagara Falls, the researchers say.