All 4 were naturally triggered.
Colorado’s high mountains saw up to 20″ of snow this week.
Early season snowfall in Colorado can sometimes lead to weak layers in the CO snowpack that last all season long.
Colorado Avalanche Summary
by Colorado Avalanche Information Center
The first serious snowfall of the year favored the Sawatch Range, Flat Tops, Park Range, and the Front Range from the Loveland Pass area north. About two feet of snow accumulated in the deepest areas. Less snow added up in the Central or Southern Mountains. Winds were drifting snow over all mountain areas.
Observers reported the first avalanches of the season with the storm. We have recorded five natural avalanches on northwest, north, and northeast aspects above tree line. The avalanches all broke several feet deep, to the ground in some spots. The largest of the avalanches “Left sizable debris for early October”.
The weather looks dry and sunny through the weekend. It will be a nice time to be in the mountains, but you will need to consider avalanches on steep, snow-covered slopes. Nearly every fall, avalanches catch eager riders and late-season hikers off-guard. Hunters traveling through the high country need to exercise caution on steep, snow covered terrain. Please be thinking avalanche if you visit steep slopes in the high country. Below we describe some considerations for early-season fall avalanche concerns.
We will update the Statewide Avalanche Conditions as necessary. On November 1, 2017, we will resume our daily weather forecasts. Our backcountry avalanche forecasts will begin in mid-November.
If you are going into the Colorado high country use our Weather Stations by Zone page to check current conditions.
Snowpack and Avalanche Discussion
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 this fall.
Most avalanches happen during or right after a snowstorm. However, any time new snow falls and the wind moves it through the terrain, avalanches are possible. New snow often has a hard time sticking to hard, icy old snow surfaces, so a fall snowstorm can produce small avalanches if it falls onto old snow, grassy areas or rock slabs. The best way to manage these avalanches in the fall is to have a current weather forecast, recognize when there is enough snow to produce avalanches, and select terrain that minimizes your exposure to the risk.
Storms Slab avalanches are the release of a soft cohesive layer (a slab) composed of new snow that breaks within the storm snow or on the old snow surface. They often form when new snow falls with light winds or in wind-sheltered areas. They typically last for a few days. You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps like gullies or cliffs, or slopes that end in timber or scree fields.
With Wind Slab avalanches, wind-drifted snow forms the cohesive layer (a slab). Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Drifted snow is often smooth and rounded, and sometimes sounds hollow. They form in specific areas leeward of terrain features. You can reduce your risk from Wind Slab avalanches by sticking to wind-sheltered or wind-scoured areas and avoiding drifted spots.
Loose Dry avalanches are a release of dry, unconsolidated snow. They start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Loose Dry avalanches are usually relatively harmless to people. They can be dangerous if they catch and carry you into or over terrain traps like gullies or cliffs, or slopes that end in timber or scree fields.