Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Skiers and riders have been finding the safest riding and best powder where the snowpack is deep and protected from the sun and wind on northerly aspects.   This week, several large natural and triggered avalanches have occurred as you move towards sunnier terrain (easterly or westerly facing) where there are problematic crusts buried up to 3 feet deep.  The most recent was a very large avalanche triggered on the southeast face of Mt. Baldy yesterday.  There have been several close calls around the state over the past few days, and sadly, a fatal accident on Friday near Marble.  Bring an acute sense of distrust to the backcountry today; this isn't our typical "spring snowpack."   

Avalanche problems

  • Persistent Slabs

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

    There are several faceted crusts in the upper few feet of the snowpack that have produced dangerous avalanche activity this week.  Most persistent slabs have failed on east and southeast aspects, though we suspect similar structures exist on westerly aspects.   Carefully assess the snowpack and give yourself a margin for error if you are riding in steep terrain.  You can reduce your risk by traveling to aspects where the problem hasn't been as active.  Choose simpler terrain when in doubt.  

     

    This very large persistent slab was triggered by a snowmobiler on 3/18.  

  • Wind Slabs

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

    Yesterday's northwest winds were just strong enough to drift the low-density snow into sensitive drifts in a few alpine locations.  Today, winds shift to the southwest and west, and could continue to form small, sensitive drifts.  You're most likely to encounter the issue at higher elevations below ridges or in cross-loaded gullies.  Wind slabs will feel stiffer and thicker than the rest of the snow surface.  Look for blowing snow or rounded lenses of smooth-looking snow to identify the problem.   In wind-protected terrain, plan to manage for small loose snow avalanches, of the dry variety on northerlies and wet variety on southerlies.  

    A skier triggered wind slab yesterday near Yule Pass.  

Avalanche Discussion

Evidence continues to mount that our persistent slab problem is the real deal.  Yesterday afternoon, a snowmobiler triggered a very large avalanche several feet thick on Mt. Baldy.  With only a few data points so far, we've been speculating that our March 10th interface is more of an issue in terrain where the winds didn't blast it into windboard in the alpine, but yesterday's slide in the alpine rejects that notion.  After several months without a well-established persistent slab issue in our deeper zone, it's easy to get anchored to aggressive travel habits; many of the near misses around the state in the past week have involved numerous people caught at once while ascending (Example A, Example B).  We are in a stepping-back mindset right now, with limited but unnerving data points regarding our persistent slab issues, especially with another major storm impacting the region starting tomorrow.

We're deeply saddened to share the news that Friday's avalanche in Marble resulted in a fatality.  The slope held an unusually shallow snowpack, likely from frequent avalanche activity this winter.  The past two atmospheric river events last week brought an immense amount of warm, dense snow, which has helped fill in terrain where the snowpack is often thin and rotten, or formed slabs in snow-starved areas that typically remain shallow and weak during a normal winter.  This observation from Pitkin highlights the issue: "I can see this slope from my house and it's the 1st time I've seen it slide in the 13 years I've lived here."  Keep that in mind as we go into yet another atmospheric river event next week: places like Almont, Taylor River Canyon, and the southernmost parts of our forecast area will likely see more unusual avalanche activity in areas that don't often produce avalanches.  This video from Reno Ridge last week demonstrates why.   You can find terrain with unusually shallow snow depths in either of our forecast zones, especially in very steep, rocky, or extreme terrain.  

The avalanche danger will start rising tomorrow and become increasingly dangerous through midweek, as yet another wave of storms batters the Elk Mountains, producing both storm instabilities on weak snow surfaces and persistent slab activity.  

Events:  The Al Johnson race is today! Information and registration are here.  Day of race registration and bib pick up 9-11 a.m. at the Adventure Center in Mountaineer Square. Proceeds go to the CBAC.

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