Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
View on map

Avalanche danger

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Out of date — this forecast expired 2 years ago.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

Highlights

Avalanche conditions are more dangerous the higher you climb into windloaded terrain.  Strong winds over the weekend formed dangerous slabs on windloaded terrain features, evidenced by a continuous stream of large avalanches.  The safest riding is in wind-sheltered terrain at lower elevations, where slab instabilities are smaller and less common. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    Snow and wind-loading in the past week have formed a new generation of slabs up to several feet thick over small-grained facets in the upper snowpack.  Numerous large slab avalanches have occurred on this layer in the past week.  Slabs are larger and most active near and above treeline on wind-loaded slopes, especially on colder aspects.  For a safer day, avoid recently windloaded slopes while staying alert for potential instabilities on wind-sheltered terrain.  

    On unusually shallow slopes, most commonly in the Southeast Mountains, there is still a small potential to trigger a destructive avalanche that breaks on deeper weak layers. The most concerning structures are on northerly aspects near and above treeline where snow depths are less than 170 cm, or where large cornices fall onto slopes.  

    A large persistent slab in Racoon Basin triggered by a shallow windslab on Sunday.  

  • Wind Slabs

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

    Strong southwest winds over the past few days formed wind slabs of varying thickness favoring north and east facing terrain.   This afternoon, winds increase out of the north and will start to form shallow wind slabs favoring southerly facing terrain at higher elevations. Wind slabs will be most common below ridgelines, behind rollovers or tree fences, and in crossloaded gullies.  Blowing snow and cracking in the snow are signs of the problem.  Wind slabs could be dangerous by themselves, or they could step down and trigger a larger persistent slab avalanche described above.  Seek out softer snow in terrain protected from the wind to avoid the problem.  

    A wind slab triggered by an easily triggered cornice on Schuylkill Ridge on Sunday. 

Avalanche Discussion

The jet stream has finally moved on, bringing the Elk Mountains relief from the prolonged period of strong southwest winds.  Poor visibility limited our observations yesterday, but there was evidence of continued natural persistent slab activity on Mt. Emmons, and a snowboarder triggered a sensitive cornice fall and wind slab yesterday on Schuylkill Ridge.  The sensitivity of these issues will gradually decrease today with wind transport diminishing.  However, winds increase out of the north this afternoon, and there is isolated potential for more natural activity as winds find a fresh fetch of snow to transport.  Stay alert for shallow but sensitive wind slabs developing on the slopes that were getting wind-scoured all weekend.  

Avalanche conditions are safer below treeline because slabs aren't as well-developed and our March weak layer got cooked off on more slopes.  We dropped the danger to Low below treeline in the Southeast Mountains now that overhead hazards have significantly diminished, and because we have not received any reports of slab avalanches or signs of instability at lower elevations in the past week.  In the Northwest Mountains, slabs are a bit thicker and we've seen a few more triggered avalanches below treeline (ex. Camo Glades, Baxter Basin), so a bit more caution is advised in the deeper zone.  Instabilities below treeline are most likely found on slopes exposed to recent wind drifting or on very steep or unsupported terrain features.  

Sunny weather and a warming trend starting tomorrow will put wet avalanche concerns back on the menu for the rest of the week.  Plan on early starts this week to stay ahead of the issues.  Tomorrow, I expect we'll see some shallow wet loose activity.  We may be dealing with larger wet slab concerns by midweek, given that our most active weak layer is only 1 to 3 feet deep, a relatively short distance for mobilizing meltwater.  

 

Regions covered