Snowfall increases avalanche risk
November 23, 2000
DURANGO, Colo. (AP) Snowfall in the San Juan Mountains is nearly twice as deep as last year, but experts say wind and temperatures are more important in determining the avalanche risk than snowfall amounts.
More than five feet of snow blankets most of the San Juan Mountains, with most of that dumping all in one month, Andy Gleason, a forecaster at the Silverton Avalanche Forecast Center, said.
Red Mountain Pass is 197 percent of normal for this time of year, and Coal Bank Pass levels are 167 percent of normal, he said.
Gleason said the sheer amount of snow does not play as much a part in causing avalanches as do weather conditions, mainly because varying weather conditions affect the way snow bonds.
”It’s not the amount of snow, it’s how well the layers bond to each other,” he said. ”There are a lot of weak layers already, and the wind slabs on top of that haven’t helped much.”
Wind makes snow hard, stiff and more prone to slide when triggered, said Silverton forecaster Jerry Roberts. ”Wind is like the architect of an avalanche,” he said. ”When wind-blown snow is fractured, it’s like a broken pain of glass.”
The Silverton center reported southern winds last week of up to 30 mph, Roberts said. Along with more wind and more snow, cold temperatures are also expected to continue.
Cold temperatures in the past two weeks have kept the upper levels of snow light and fluffy and very weak, Roberts said.
”It makes for great skiing, but it’s not so good when you’re trying to get another layer of snow to stick to it,” he said. ”The layer now could be a poor layer for the next couple of storms.”
Roberts said warm weather coupled with more snow would decrease avalanche danger for the winter.
At least six people have been caught in avalanches statewide this year, three of those in the San Juan Mountains, he said. No one was killed.