This story has been updated.
Update, Tuesday:
The National Weather Service has canceled the flood warning for Mendenhall Lake and River.
Juneau’s second glacial outburst flood of the year crested Monday night at 7:30 p.m. at 9.6 feet.
Original story:
A second, minor glacial lake outburst flood is underway in Juneau. Water levels in the Mendenhall Lake and River are slated to crest sometime Tuesday morning.
The National Weather Service issued a flood warning Monday morning after indications that the water in Suicide Basin had started to release from the basin and into Mendenhall Lake.
The National Weather Service in Juneau predicts water levels will be much lower than last month’s record-breaking flood, based on the estimated current volume of Suicide Basin.
Nicole Ferrin, the NWS warning coordination meteorologist, said at a press briefing Monday afternoon that recent heavy rainfall may influence how much water is in the basin and lake.
“We’ve got fall storms coming through, so that’s going to contribute to the base flow of everything,” Ferrin said.
NWS currently forecasts a crest between 11 and 12 feet between 2 a.m. and 6 a.m. Tuesday. Ferrin says the forecast could change as new information becomes available.
Flooding is expected around Mendenhall Lake and Mendenhall River, including around the Mendenhall Glacier Visitor Center, the Mendenhall Campground, Skaters Cabin Road, View Drive and potentially Back Loop Bridge.
Denise Koch, the city’s director of engineering and public works, said at the briefing the city is advising residents on View Drive to evacuate the area out of “an abundance of caution.”
The city also plans to close off Meander Way to local traffic only and reinforce the HESCO flood barriers in that area before the crest. Koch said most homes in the Mendenhall Valley should be spared from flooding.
“We are confident that the HESCO barriers overall will perform in a GLOF of this magnitude, similarly to how they were overall, pretty successful in the August event,” she said.
The temporary levee the city installed along the Mendenhall River this year protected hundreds of homes during last month’s flood, which crested at 16.65 feet. But water still leaked through some sections and flooded several streets.
A similar secondary glacial lake outburst flood occurred last October. The city reported minimal impacts to neighborhoods. The city plans to close the Kaxdigoowu Heen Dei,or Brotherhood Bridge Trail,and potentially other streets.
This is a developing story. Check back for updates.
Find more information about glacial outburst flooding, including coverage of August’s flood, here.
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