Avalanches are possible any time you find snow on steep slopes in Colorado. Although accidents are less likely in the summer, there have been fatal accidents every month of the year. Below is some general avalanche safety advice for the spring and summer. Our next scheduled update is November 1, 2013. We will continue to issue updates via Twitter if we anticipate unusually dangerous conditions before then.
We have stopped issuing weather forecasts for the 2012-2013 season. You can get current weather forecasts from the National Weather Service here.
Our Computer Model Forecasts are updated four times a day and will run through the summer. If you are going into the Colorado high country use our Weather Stations by Zone page to check current conditions.
Avalanches are possible in the mountainous areas of Colorado whenever you find snow on a steep slope. In general, you should consider the consequences of being caught in an avalanche before you cross any steep, snow-covered slope, but below are some avalanche problems you may encounter over the summer. You can look here for observations of snow conditions and reports of avalanches any time of the year. We also want to hear your reports on backcountry conditions and avalanche observations, so please send us your observations.
Storm Slabs, Wind Slabs, and Loose-Dry Avalanches
Most avalanches happen during or right after a snow storm. Later in the spring and throughout the summer, snow storms are less likely. But every time new snow falls and the wind moves it through the the terrain, these avalanches are possible. New snow layers often have a hard time sticking to hard, icy surfaces, so a summer snow storm can produce lots of small avalanches if it falls onto old snow. Even small avalanches are dangerous if they can push you off a cliff, or into rocks, trees, or a gulley. The best way to manage these avalanches in the summer is to have a current weather forecast, recognize when there is enough new snow to produce storm avalanches, and select terrain that minimizes your exposure to the risk (avoid areas where there was old snow, wind pillows along ridgelines, cross-loaded features like rock outcrops and subridges). Here is an example where a new-snow avalanche produced an fatal accident a few years ago.
Wet Slab and Loose-Wet Avalanches
As the snow heats up and begins to melt, water moving through the snowpack can produce avalanches. The most common wet avalanches are loose, sluff or point-release avalanches. These are most dangerous if they can push you off a cliff, or into rocks, trees, or a gulley. You can manage these by starting your tour early, when the snow is frozen, and ending your tour early before the snow gets too wet. Watch the overnight low temperatures at high-elevation weather stations, but remember that air temperature, cloud cover, and wind all affect how the snow freezes each night. Wet slab avalanches are much more dangerous. These often occur when melt water hits a persistent weaker layer that formed earlier in the winter or during a dramatic warm up that lasts a few days. The snow conditions that produce wet slab avalanches last longest on high-elevation, northerly slopes as we move into summer. Look at the old snow layers to see if they are still dry or turning to coarse spring-time snow. Regardless of what wet avalanche you are worried about, remember to stay off and out from under steep snow-covered slopes when you start to sink into the wet snow more than about 6 inches. Here is an example of a fatal accident in a wet slab avalanche from last year.
Throughout the winter, strong winds build large over-hanging snow features along ridgelines. These cornices can break off at any time of year, but also break and roll onto lower slopes during spring melt. It is hard to predict when these large masses of snow will break, so it is best to avoid traveling under them and give them a wide berth when you are traveling along them. If your route goes under one, use a similar approach as wet slab avalanches and look for a good overnight freeze and try to get past them early in the day. Remember that the sun may hit them earlier than it hits the slopes below them.