Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
View on map

Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

The most likely place for you to trigger an avalanche can be found on recently drifted features on the east half of the compass.  Use caution near leeward terrain features and steer away from terrain with signs of wind-loading.  In sheltered areas, you could trigger an avalanche that breaks 2 to 3 feet deep on a layer of surface hoar on slopes facing west to north to east.  If you choose to ride in avalanche terrain you can reduce the consequences of an avalanche by selecting smaller slopes free from terrain traps.  Wind-sheltered southerly slopes offer a lower risk of slab avalanches but pay attention to warming surface snow throughout the day.

Avalanche problems

  • Persistent Slabs

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

    A new round of weak layers was buried on February 2nd. These weak layers consist of widespread surface hoar and facets on most east, north, and west-facing slopes, and along with some faceted crusts on higher elevation southerly aspects. Slabs about 2 to 3 feet thick over these weak layers are becoming more stubborn, but can still be triggered by skiers and riders. This avalanche problem can be remotely triggered from flat terrain, or may propagate further than expected.  Shooting cracks or collapses are a clear sign of danger, but these obvious signs of instability will not always show themselves before an avalanche releases.  There is isolated potential to trigger older, larger slabs on weak layers deeper in the snowpack, most likely from shallow terrain features or step-down avalanches.  

    You can reliably avoid trouble on terrain with slope angles less than 30 degrees that are free from overhead steep terrain. Lower elevation southerly aspects offer safer options for steep terrain.  

     

    2/19:  A remotely triggered persistent slab above the Slate River

  • Wind Slabs

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

    Westerly winds drifted up to a foot of recent snowfall.  Wind-loading was observed throughout Thursday and may leave recently drifted terrain sensitive to human triggers on Friday.  You are more likely to encounter sensitive Wind Slabs above treeline, but can still find them near treeline.  Drifts will be forming below cornices, leeward ridgelines, and in gulleys or concave catchments at higher elevations.  There is isolated potential for wind slabs to step down and trigger a much larger persistent slab avalanche, like this recent avalanche on Mt. Owen.  The safest bet is to avoid recently drifted terrain features and give the snowpack time to adjust to the new load.  This will allow you to avoid triggering a Wind Slab and reduce the chances of being surprised by a deeper breaking avalanche.

    This recent wind slab triggered at Irwin exemplifies the type of wind slabs that you could trigger.

Avalanche Discussion

Northwest Mountains:  Up to a foot of recent snowfall was blown by westerly winds over several days.  Poor visibility on Thursday thwarted views into the range and left some uncertainty about the extent of recent natural avalanche activity.  One observer noted a large recent avalanche in Yogi's on Schuylkill Ridge (northeast-facing, near treeline) that may have failed a few feet deep.  This serves as a good reminder that the surface hoar layer buried in early February remains problematic, particularly for terrain with recent drifting.  Remain suspicious if you plan to travel through terrain highlighted by the Persistent Slab rose; signs of instability have been relatively infrequent and may not warn you before releasing a dangerous avalanche.  Multiple tracks could be on the slope before someone finds the right spot to impact the weak layer.  You can always select low-angled slopes to manage the risk, but if you choose to ride steeper terrain, it would be wise to select terrain with less severe consequences.  Cautiously approach steep terrain with a keen eye for the consequences as a triggered avalanche on the surface hoar layer will be large and dangerous.  Persistent weak layers like surface hoar often surprise skilled professionals.

Southeast Mountains:  Avalanche conditions continue to hover near a dangerous level around the Southeast Mountains.  Generally, slabs above the early February weak layer (and basal weak layers) are thinner and more prone to human triggering.  Recent wind drifting makes it more likely for you to trigger an avalanche deeper in the snowpack.  A second-hand observation from upper Cement Creek, suggested deep failing avalanches near Hunter Hill and Crystal Peak in the past few days (forecasters plan to travel through this area today to get more details).  Avoiding terrain with recent drifting is a straightforward choice today.  In sheltered areas, the slab above the February surface hoar layer is 1 to 2 feet thick which leaves it squarely within the depth for human-triggers.  One observation from below treeline in the Southeast Mountains suggested a decreasing sensitivity to human triggers with moderate results in an Extended Column Test.  This merely suggests an incremental improvement in avalanche conditions; we are far from being out of the woods, particularly in the Southeast Mountains where slabs are thin.  Carefully manage slope angles in sheltered terrain highlighted by the Persistent Slab rose to reduce the risk of avalanche.

Regions covered