Just had a little trip up to my favorite city of Juneau, Alaska. So lovely. Here’s just one story from the trip.
There is a Big Thing going on there right now which is essentially an impending flood that is going to happen any day now. It’s an “Outburst Flood” or GLOF (“glacial lake outburst flood”). The weather.gov page explains in one graphic:
So there is the famous Mendenhall glacier. Mendenhall lake, formed by it’s melt, is like 30 minutes from downtown Juneau, so it’s quite accessible for even cruise ship visitors to go get a look.
Suicide Basin fills up with water during the warm months from glacial melt, and the Mendenhall glacier acts as an ice wall between it and Mendenhall lake. But at some point, the basin gets so full, the water from it starts flowing underneath/through the glacier into Mendenhall lake.
There is a river from Mendenhall lake out to the ocean. When Mendenhall lake starts rising from the basin runoff, it goes out that river, and that river rages for a good couple of days. Hence the flooding.
That river? Half the people in Juneau live in the Mendenhall Valley where that river runs directly through. Now it’s not all under evacuation flood watch, but some of it certainly is. And it’s rather unknown how bad any given year is going to be.
It’s been very bad:
My friend Justin lives in the Mendenhall Valley, not far from the river, and when it goes, he can loudly hear the river raging. As I type, we’re just days away from the prediction of August 8-12 from the basin draining.
Justin and I climbed up Thunder Mountain (oof, it was actually 8.5 miles and 3,800 ft) and from the summit had a great look down at the entire valley, seeing the whole river area at once.
Driving around there on roads by the river, you can see how the city has put up huge wall embankment things to hopefully stop the worst of the damage:
Seems like it’s fairly unknown if it’s really going to work.
If you’re interested, KTOO did a mini podcast on it last year getting into some details. Like one of the proposed solutions are literally bombing the glacier 🤔. Apparently now it’s leaning more toward the Army Corps of Engineers digging a drainage hole of sorts, but I don’t think any of it is totally sorted out yet.