Heavy snow this summer has been causing avalanches in the Colorado high country. Interstate 70 was closed on Vail Pass early this morning, in fact.
Here is why there are so many avalanches:
The “historic avalanche cycle” started in October and November, when Colorado got a lot of early-season snow. That snow rotted into facets: imagine ball bearings or sugar-like snow that can’t be formed into a snowball. That’s the weak layer. Then came lots more snow. In the past month, CAIC forecasters started seeing fewer avalanches releasing on that weak layer on the ground.
Then came even bigger storms — like this past weekend when 40 inches fell in two days in the Central Rockies, or the 50 inches that piled up in 50 hours in the Four Corners area two weeks ago. And the slab grew even larger and heavier, all sitting atop the weak layer on the ground. That means every falling flake boosted the chance of a catastrophic slide. And in this latest round of storms, the final flake fell on slide paths above I-70.I lifted this video and quote from an article in the online Colorado Sun — go there for more video and background information.