Moderate flooding is expected from a glacial dam outburst in Alaska’s capital city, with a flood warning being issued after an outburst from a glacial lake in Juneau. The Suicide Basin, a side basin of the Mendenhall Glacier, has been causing glacier lake outburst floods annually since 2011, leading to inundation along Mendenhall Lake and Mendenhall River.
Nicole Serrin, warning coordination meteorologist with the National Weather Service in Juneau, stated that they anticipate moderate flooding from this event, rather than major flooding. Residents were given 24 to 36 hours to prepare for the flooding, with the warning in effect until Monday. The forecast indicated that the river could crest at around 11 to 11.5 feet (3.35 to 3.5 meters) early that day.
Officials cautioned people to steer clear of the river, especially due to the recent snow making the banks very slippery. Suicide Basin fills with rainwater and snowmelt during the spring and summer, building up enough pressure to force its way out through channels it carves beneath the Mendenhall Glacier.
The basin has been refilling with fall rain over the past few months, but it remains uncertain how quickly it will drain or if it will completely empty. In August, an estimated 100 homes and businesses were damaged when the lake sent floodwaters into neighborhoods. The Mendenhall River reached a record 15.99 feet (4.9 meters), exceeding last year’s flood levels by about a foot, and extended further into the Mendenhall Valley, according to officials.
Juneau, a city of approximately 30,000 residents in southeast Alaska, is accessible only by plane or boat. The authorities continue to monitor the situation closely to ensure the safety of the residents amidst the ongoing flood warning.