Avalanches weren’t – and aren’t – only a backcountry threat

This web exclusive appeared on hcn.org on March 11, 2014

In the handful of times I’ve visited Missoula, Montana, the grassy slopes of neighboring L- and M-emblazoned Mounts Jumbo and Sentinel have never looked any more threatening to me than the hogbacked foothills that yaw out of the ground west of Boulder, Colorado, my hometown. Velvety, yes. Curved like a set of relaxed shoulders, yes. Welcomingly draped in the low-angled sun of late afternoon, yes. Avalanche death zone? Not so much.

But on Feb. 28, an unusually intense blizzard snapped a wet quilt of deep snow over the valley, rumpling it into drifts and slabs with gusts up to 50 mph. Atop Jumbo and Sentinel, as well as the surrounding mountains, a weak crust of ice that unseasonably warm weather had glazed over the existing snowpack earlier in the week strained beneath the weight. When a group of snowboarders started down Jumbo — closed since November to protect a wintering elk herd – around 4 p.m., that strain released spectacularly. A large slab avalanche ran from near the mountain’s peak almost 1,300 vertical feet into a neighborhood on the valley floor, obliterating a two-story house, damaging several other homes and vehicles, and worst of all, burying three people. More…

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