Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
View on map

Avalanche danger

Thu
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
Open full map
Out of date — this forecast expired last year. You’re viewing past conditions, not the current bulletin.

Highlights

Windloaded slopes are the most dangerous, where freshly drifted slabs up to a few feet thick are sensitive to skiers and riders.  Instabilities in the new snow are smaller and easier to manage in windsheltered terrain at lower elevations.  There's a small chance you can trigger a surprisingly large avalanche breaking deep in the snowpack on the north half of the compass, most likely from very steep, rocky, and/or wind-affected terrain, or from a fresh wind slab that steps down.  

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    In the Northwest Mountains, skiers and riders easily triggered soft wind slabs 1' to 2'  thick yesterday, most commonly on leeward slopes favored by gusty north to west winds.  With winds continuing overnight, similar instabilities are a concern today.  Drifts will be largest and most dangerous below alpine ridgelines, or can spell trouble in any windloaded or crossloaded terrain above terrain traps.  Look for cracking in the snow, thicker or denser feeling snow, or other signs of obvious drifting to identify the problem.  There is an outside chance that a Wind Slab could step down and trigger a deeper Persistent Slab where the two problems overlap. 

    A skier triggered wind slab on Purple Ridge  (3/4/2025) 

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    Buried facets and depth hoar are a concern on the northern half of the compass.  Slabs on top of these weak layers average 2.5 to 4 feet thick in wind-sheltered terrain. Slabs are thicker and harder in wind-drifted terrain and can step down through older slabs to the ground.  This problem has become stubborn to triggers, often requiring a thin spot on the slope, such as near buried rocks or where slabs thin from wind effects. Avalanches can break widely across multiple terrain features and be remotely triggered from flat terrain near or below steep slopes without warning signs. The problem can be avoided on slope angles consistently less than about 30 degrees and is very unlikely on southerly aspects.  

    A couple of persistent slab avalanches were remotely triggered in the upper Cement Creek area on Friday, 2/28. 

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    In favored areas that picked up around a foot of snow or more, manage for storm instabilities in wind-sheltered terrain.  There's potential for shallow slabs or sluffs to break within the storm snow or at the storm interface, which consists of crusts on southerly aspects and small-grained facets on northerly aspects.  As sunshine moistens the snow surface on sunny aspects, sluffs could release naturally and get heavier and wetter as the day warms up - evolving into a wet loose problem.    

    A skier triggered storm slab yesterday at Irwin.  

Avalanche Discussion

Yesterday brought a return to winter wonderland, with settled storm totals reaching 12" to 16" in the Northwest Mountains, and less than 5" in the Southeast Mountains.   Observers reported sensitive instabilities in the new and drifted snow, especially on wind-loaded slopes and snow-favored areas.  Wind drifting continued overnight and may continue today.   The most dangerous slopes are leeward features at higher elevations, where fresh slabs will be thickest and potentially most sensitive.  Carefully consider the slab size and terrain consequences before crossing any leeward terrain features.  Some areas, like Irwin, picked up enough snow for storm slab instabilities yesterday. Although this problem won't be as active today, storm slab issues may linger on the steepest slopes or northerly aspects where the storm interface is weakest. Furthermore, warming temps and sunshine through midday might cause solar slopes to shed as point release avalanches once the snow becomes damp, particularly in the snow favored areas.  Natural sluffs, rollerballs, or pinwheels will signal decreasing stability and impending dry-to-wet loose slides. That's a laundry list of problems, but let's rephrase it into simple layman's terms: manage the new snow - there's more of it in the deep zone and on drifted slopes.  

While fresh surface instabilities will be the most common and obvious problems, don't forget about the deeper issues plaguing our snowpack this season.  This video from yesterday describes how slopes with a deeper, more uniform snowpack, or more reliably, on southerly aspects, offer lower risks for getting surprised by a larger, more dangerous avalanche.  From a big-picture view, the snowpack trends from deeper and stronger to shallower and weaker as you move from the Slate and Kebler Pass areas to Brush or Cement Creek areas.  Of course, there is always variability to those general patterns - you can find weaker snowpacks throughout the whole forecast area in very steep, rocky, or heavily wind-affected terrain.  Loading yesterday and later this week will stress these buried weak layers and cause increasing concerns for human triggers or natural step-downs.  

A winter storm featuring strong winds and heavy snowfall will increase the avalanche danger tomorrow, and the danger could rise to High at upper elevations on Thursday night, depending on how the storm evolves. Stay tuned.  

Regions covered