Weather Service keeping an eye on Suicide Basin levels

Empty now, experts monitor it in case of another jökulhlaup, flood watch

Suicide Basin is nowhere near full, but the subglacial basin that has caused surprise flooding two years in a row has the full attention of meteorologists who monitor its water levels.


“We know that last year it was about 52 feet on the gauge before it released,” said Tom Mattice, CBJ Emergency Programs Coordinator. “But if we see it getting close to last year’s number, then we want to be extra careful.”

As of Thursday, the basin was empty. But when it fills up and releases, like it did in July 2011 and 2012, the subsequent impact is referred to as a glacial outburst flood, or jökulhlaup, and could cause damage.

“It’s kinda a new phenomenon here,” said Tom Ainsworth, the Meteorologist in Charge of the National Weather Service in Juneau. Ainsworth said that it is common in Southeast Alaska.

Originally an Icelandic term, jökulhlaup is the word used to describe large and often abrupt releases from subglacial lakes or reservoirs.

With the recent heat wave and more sunny weather hovering in the high 70s for the weekend and next week, flooding in and around Mendenhall Lake is something to keep on the radar.

It’s around this time, or within the next few months, a major outburst could happen again.

“We had a very late onset of summer here — we had days with snow in May. So there’s still quite a bit of snow in the basin,” said Ainsworth. “But we’ve also had this warm spell accelerating some melting.”

There are monitoring systems at the Mendenhall Glacier and in the basin tracking water levels and general equipment tracking glacier progress throughout the year.

Jamie Pierce, a research technician in the environmental sciences program at the University of Alaska Southeast, said there are two pressure transducers sending updates on water levels every hour.

“We have a number of instruments in there,” said Pierce. “We’re tracking that movement as well, and we have a timelapse camera.”

When the basin fills up, it might drain from an existing drainage area that was created in years past, or it could drain through a new area, Pierce said.

“As such, it’s pretty difficult to predict,” said Pierce. “The only thing that we can do is monitor it with these pressure transducers. And it’s real-time, so I configured them such that they send out the average sample rates.”

Mattice, the Emergency Programs Coordinator, wanted to be clear that in the event that the basin bursts, they hope to issue advisories 24 hours in advance and that nothing is certain, even if the water levels reach 52 feet like in 2012.

“There are a whole bunch of variables,” said Mattice, including the amount of water ice is displacing, what the rate of release would be or the tide levels when it does. “Even thought we could see the exact same gauge as we did last year, it doesn’t mean the release we saw last year.”

To track the water levels, go to and click on “Hydrology.”

• Contact reporter Kenneth Rosen at 523-2250 or at


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