Thu December 20, 2012

For The Mountains, Snow Finally Arrives And Brings Avalanche Danger With It

Avalanche danger in the mountains has ratcheted up quickly over the past week. Get ready for the possibility of high risk being the norm this season, all thanks to the warm, dry fall and late winter.

Aspen Public Radio's Luke Runyon reports

As snow falls, it begins to layer. Each layer gives insight into the snowstorm that created it. Put them all together and you get this winter’s story.

“So like a tree ring, you can read a history,” says Colorado Avalanche Information Center (CAIC) forecaster Spencer Logan.

A close up look of near surface facets
Credit CAIC / Colorado Geological Survey

The story so far this year is a bit worrisome. Snowpack in November and early December withstood high temperatures and winds, and very little extra snow fell to create a stable base layer. “So that early season snow that we got, it sat on the ground. And it goes through a process we call faceting,” Logan says. “The snow grains get bigger and bigger and as they get bigger they get less and less strong.”

That means the base is likely to stay weak this winter. That’s why when the most recent winter storm rolled through and dropped considerable amounts on the mountains, the avalanche risk went through the roof almost immediately.

The snowpack is so precarious even normally safe areas could be dangerous. For anyone attempting a trip into the backcountry, extreme caution will be a necessity the next few days.

“Avalanches are being triggered from a distance, sometimes the valley bottoms. That means you can be travelling in what seems to be safe terrain and trigger an avalanche up above you,” Logan says.

If you are heading into the backcountry, you can grab the latest backcountry forecasts straight from the CAIC online.