Colorado Avalanche Information Center · observations

When, where, and who sets them off

Every avalanche observation reported to CAIC. Click anything — a petal of the rose, a season, a zone, a trigger, a problem — to filter the whole page. The link always carries your view.

Avalanches recorded
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Triggered by people
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Big enough to bury a person (D2+)
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Observations with people caught or involved
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Terrain and timing

Which slopes slide, and when in the season.

Avalanche rose

Aspect × elevation. Centre = above treeline, outer ring = below. Click a cell to filter.

Observations with unknown aspect or elevation are left out.

Season calendar

Avalanches per week, each row one season (Oct → Jun). Grey bar = season total. Click a season to filter to it.

Darker = more avalanches (square-root scale).

Where

Forecast zones ranked; click a zone to filter, or open its profile.

Observation density

Each disk is a ~5 km cell sized by avalanches; the orange core is the human-triggered part (area-true). Red dot: people caught or involved there.

CAIC publishes no boundary for Grand Mesa; 512 observations have no usable coordinates.

Forecast zones

Avalanches recorded, with the human-triggered share in orange.

Counts track reporting effort as well as hazard: Gunnison's lead reflects dense observer coverage around Crested Butte.

Who and how big

Triggers over time, and whether people set off smaller slides.

What triggered them, by season

Share of each season's avalanches. Click a colour to filter to that trigger.

"Explosives" is control work by ski areas and highway crews.

Size: human vs natural

Share of each group's avalanches at each destructive size. D2 can bury a person; D3 a car.

Human-triggered Natural
Shares, not counts: natural avalanches outnumber human ones about 3 to 1. Unrated sizes excluded.

Avalanche problems

Recorded on about a quarter of observations, mostly since 2020.

Which problem, which month

Avalanches by forecast problem and month of the season. Click a problem to filter.

Observations with no problem recorded are left out.

How deep they break

Crown (slab) depth in 6-inch bins, by problem, ordered shallow to deep. Each row is scaled to its own total.

Only observations with a measured crown depth (≈5k); cm converted to inches.

The observations

Newest 200 in the current scope. Click a row for the observer's notes.

About these numbers

Source. The Colorado Avalanche Information Center's public observation API (api.avalanche.state.co.us), downloaded 2 Oct 2026: 29,010 observations reporting 45,536 avalanches. Observations come from forecasters, professionals and the public.

Avalanches vs observations. One observation can report many avalanches (up to 100). Totals count avalanches; a missing count counts as one. Size, aspect and trigger apply to the whole observation.

Seasons. A season is a water year: "2023-24" runs 1 Oct 2023 – 30 Sep 2024. The page starts at 2010-11, when CAIC's digital record becomes consistent; earlier seasons hold only a few back-entered events.

Human-triggered share. Of avalanches with a known trigger, the share set off by skiers, riders, snowshoers, snowmobilers, hikers and other people travelling — not explosives control work. Unknown triggers are excluded from the denominator.

People involved. CAIC's incident flag on the observation: a person or property was caught or involved. It is not a fatality count.

Reporting bias. More observers means more recorded avalanches. Compare shares and timing across zones with more confidence than raw counts.