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FRISCO — State officials are warning backcountry recreationists and mountain residents to stay wary of avalanches after a number of slides made their way down paths in the Tenmile Range and Loveland Pass in recent days.
While some people’s avalanche awareness tends to kick in with each new snowstorm, experts said high winds also can create dangerous conditions, even without any new snowfall.
“With the avalanche activity we’ve seen in the last day in the Vail and Summit County areas, most are classified as a natural triggers,” Colorado Avalanche Information Center Director Ethan Greene said. “With the winds we’ve been seeing, it will start to move snow around, and it’ll strip it off the upstream side of the terrain and load the slopes on the downstream side of the terrain. It’s just like if you have a really big snowstorm — it adds weight to the snowpack, and it can definitely trigger avalanches.”
There have been a number of avalanches in the Summit County area over the past couple of days, including on the northeast-facing side of Peak 2 on the Tenmile Range, the southeast-facing slope near Loveland Pass, and on Vail Pass and near the Eisenhower Tunnel on Tuesday — one of the most active avalanche days of the season so far. While the slides mostly have been categorized as small or medium, they serve as good reminders to recreationists to avoid any wind-loaded slopes.
According to Greene, wind conditions following a snowstorm can be just as vital to understanding avalanche danger as the storm itself.
“Let’s say it snows 3 inches,” Greene said. “There’s weight associated with that. You put 3 inches on top of your preexisting snowpack, and in most cases, that’s probably not going to have a huge impact. It’s not going to cause a huge change in avalanche conditions. … But as the wind hits the mountain range, it has to go over the top of it.”
Greene said that when the wind picks up, it essentially could pick up the 3 new inches of snow from the ground over a widespread area, about 50 acres for example. The wind will continue to pick up speed as it heads over the ridge of the mountain, where it will quickly decelerate and drop the snow on the other side.
“It’s not going to drop that snow over 50 acres,” Greene continued. “It’s going to drop it in a ribbon over the ridgeline. So in effect, you have 3 inches of snow that fell out of the sky, but for those slopes on the other side, you may be putting 6 feet of snow on top. That’s why the wind is so important. … The wind is actually much more effective at moving snow around and putting a lot of weight in specific areas.”
Greene emphasized that while the avalanche hazard level is trending downward following the snowstorm earlier this week, backcountry visitors shouldn’t let their guards down. There have been at least 135 avalanches reported statewide since the storm ended Monday, Dec. 9, according to the Avalanche Information Center, largely due to wind-loading on weaker layers of snowpack.
Anyone heading to the backcountry should be sure to check the up-to-date avalanche conditions at avalanche.state.co.us. The website also maintains backcountry avalanche forecasts that can provide some insight into hazards a day in advance. The avalanche hazard in the Summit County and Vail area is considerable, but even with a low or moderate rating, backcountry visitors need to use their best judgment as conditions could change throughout the day.
“We want people to read the forecast because we’re going to give you some idea of what’s been happening, and what we expect to happen that day,” Greene said. “Is the wind going to have a big impact? Where is it affecting the snow? It gives you a head start. But while you’re out during the day, you definitely want to be paying attention to this. If we see increased wind speeds, you will see an increased hazard, and that could happen during the period of a backcountry tour.”
