A glacial lake outburst flood (GLOF) originating from Suicide Basin on the Mendenhall Glacier has caused severe flooding in Juneau neighbourhoods. Water levels in the Mendenhall River peaked around 3am on Tuesday, August 6, at 15.99 feet. This is over a foot higher than during last year’s record breaking outburst. Over 100 homes are estimated to have been affected this time, as per a statement by Juneau officials.
The Suicide Basin GLOF has occurred almost every year since 2011 but the last two events (this year and 2023) have been unprecedented in terms of the water levels and severity of the flooding. A state of emergency has been declared to aid response and recovery efforts in the affected neighbourhoods in the Mendenhall Valley.
In last year’s GLOF, multiple homes along the Mendenhall River were completely destroyed due to severe erosion along the river banks, which undermined foundations. As Juneau city officials point out, this year’s event did not produce the same kind of erosion but flooding was more widespread and reached many homes that were not affected in 2023.
Suicide Basin is equipped with instrumentation to monitor water levels and provide early warning when a GLOF is imminent. Flood warnings were issued by the NWS on August 4 and the city advised residents in the most affected areas to take immediate precautions on August 5.
See our blog post on the 2023 outburst for background on the glacial processes that produce GLOFs. Monitoring data, imagery from the cameras in Suicide Basin, and further information on current conditions can be found at: weather.gov/ajk/suicideBasin
