Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Heavy snowfall and strong winds are creating dangerous avalanche conditions.  The avalanche danger is Considerable near and above treeline, and could rise to Considerable below treeline if we see the high end of snow forecasts.  Manage for instabilities in the new and drifted snow.  They'll be larger and more dangerous at higher elevations where winds are drifting the snow into thicker slabs.  There's a small chance for a surprisingly large avalanche to release deeper in the snowpack on the northern half of the compass, especially in terrain with unusually shallow or variable snow depths.   

Avalanche problems

  • Storm Slabs

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

    Avalanches breaking in the new snow will grow larger throughout the day.  Slabs will be thickest, and potentially most sensitive, on leeward slopes at higher elevations. Heavy snowfall could cause sensitive storm slab instabilities in sheltered terrain.  Monitor storm totals and evaluate terrain consequences before riding in steeper terrain.  Shooting cracks indicate unstable snow, warning you to choose mellower terrain.  

    A skier triggered storm slab from last week.  

  • Persistent Slabs

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

    There is small potential to trigger a dangerous slab avalanche on facets or depth hoar layers in the middle or bottom of the snowpack.  Persistent or deep persistent slab avalanches are most likely to be triggered on the northern half of the compass and where the snowpack is unusually thin and weak.  In rare cases, they might also be triggered on deeper slopes from step-down avalanches in the upper snowpack or cornice falls. Be cautious of very steep, rocky, or wind-affected terrain with variable snow depths and slopes receiving heavy windloading today.   Southerly slopes generally lack the problem due to previous meltwater strengthening the snowpack.  You can avoid the problem on slope angles consistently less than 30 degrees.   

    This persistent slab avalanche caught and carried a snowmobiler last weekend on East Beckwith. The avalanche broke on the January drought layer 2 to 3 feet deep in the middle of the snowpack.  Note how the terrain has variable depths and shallow areas due to wind effects.  (3/8/2025) Photo: Care Flight

Avalanche Discussion

Like last week's storm, today's snowfall heavily favors the Northwest Mountains, and avalanches in the new snow are expected to be larger and more common there (See avalanche patterns from last week here).  And like last week, the storm snow is falling on the usual mixed bag of spring snow surfaces - crusts, settled powder, wind-stiffened snow, and in some cases, weaker near surface facets. These observations from Schuylkill Ridge and Upper Cement show that near-surface facets are more prevalent on the north half of the compass.   Yesterday's pre-storm winds and greenhousing likely damaged those weak layers on some slopes.  Time will tell how problematic and persistent this storm interface will be.  For today, treat the new snow as guilty until proven innocent by gathering feedback on the size and sensitivity of new slabs before riding in consequential terrain.   In areas that see less than about 10" of snow, sensitive slabs will most likely be localized to wind-loaded slopes.  With some uncertainty for snow totals today in the Northwest Mountains, we erred on the side of a higher danger rating below treeline in case a widespread storm slab problem develops in the snow favored zone, with potential for storm slab avalanches to break on mid-storm layers or at the storm interface.  

Now that we're in a loading period, we bumped the likelihood of persistent slabs back up in the Northwest Mountains and bumped the size to include D3 in both zones.  Our most concerning slopes for triggering an avalanche that breaks on old weak layers have unusually shallow snow depths - most often from previous wind erosion or avalanche activity.  In the past few weeks, these shallower slopes have fit the pattern of D2s and the characteristics of a persistent slab.  During windloading loading events, we have increased concerns for D3 deep slabs on wind-loaded slopes - most likely from step-downs or cornice falls.   This is an unlikely problem - we didn't see that happen with last week's storm - but we bumped the size up today to cover our uncertainty during today's wind-loading period.  

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