UPDATE 9:30 a.m., Oct. 1
A second glacial outburst flood is underway in Juneau, according to a flood warning the National Weather Service issued just before 8 a.m. on Thursday.
The Weather Service predicts the Mendenhall River will crest between 9.8 and 10.3 feet between 2 p.m. and 6 p.m. on Friday. A minor flood stage starts at 9 feet.
During a livestream at 9:05 a.m. this morning, Weather Service Meteorologist Andy Park said impacts from this crest should be minor.
“With 10 feet, the biggest thing will be the Mendenhall Campground, West Glacier, and also onto the visitor center — I think Nugget Falls Trail (will) start flooding as well,” Park said.
According to data from the U.S. Geological Survey, it’s not uncommon for Suicide Basin — the glacier-dammed lake responsible for the flood — to release more than once in a year. Since 2023, secondary releases that took place in September or October were significantly smaller than initial floods in August.
The flood this August peaked at 14.7 feet. The record-breaking flood in August 2025 crested at 16.65 feet, and the secondary flood that followed in September 2025 crested at 9.6 feet.
Original story:
A flood warning for a glacier lake outburst is in effect until 7:45 a.m. Saturday, according to the National Weather Service in Juneau.
A second release from Suicide Basin has started and levels are predicted to continue to drop this afternoon. The agency predicts the Mendenhall River will crest likely between 9.8 and 10.3 feet sometime between 2 p.m. to 6 p.m. tomorrow, Oct. 2.
No residential flooding impacts are expected, according to the City and Borough of Juneau. The outburst flood in August crested at about 14.7 feet.
CBJ encourages the public to avoid the Mendenhall River and follow any road and trail closures.
Flooding of the area around Mendenhall Lake and along the Mendenhall River is expected to begin shortly. Water levels will continue to rise.
This is a developing story. Check back for updates.
