Moderate flooding is expected from a glacial dam outburst in Alaska’s capital city

JUNIAU, Alaska — A flood warning was issued Saturday after a glacial lake eruption in Alaska’s capital.

Suicide pool is a tributary of the Mendenhall Glacier above the city of Juneau. Since 2011, glacial lake outbursts have occurred every year, causing flooding along Mendenhall Lake and the Mendenhall River.

“We expect moderate flooding, not major flooding, from this event,” said Nicole Serrin, warning coordination meteorologist with the National Weather Service in Juneau.

Residents had 24 to 36 hours to prepare for flooding, she said. The flood warning was in effect until Monday.

The weather forecast called for the river to crest at a height of about 11 to 11.5 feet (3.35 to 3.5 meters) early that day, the weather service said.

Officials warned people to stay away from the river. The recent snow has made the banks very slippery.

Suicide Basin fills with rainwater and melting snow in the spring and summer, eventually building enough pressure to force its way out through the channels it carves beneath the Mendenhall Glacier.

The basin began to fill again with fall rain in recent months, Serrin said. It was not certain how quickly it will deflate or if it will completely deflate.

In August, an estimated 100 homes and some businesses were damaged after the lake floods sent to the neighborhoods.

The Mendenhall River then reached a new record high of 15 feet, surpassing the level during last year’s flood by about a foot, and the water reached further into the Mendenhall Valley, officials said.

Juneau, a city of about 30,000 in southeastern Alaska, is only accessible by plane or boat.