Avalanche forecast

Gunnison

Crested Butte Avalanche Center
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Avalanche danger

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

It's getting hot in herre!  The danger is Moderate this morning, rising to Considerable by this afternoon.    Large natural avalanches are possible on sunbaked slopes. Travel early for safer travel on the southern half of the compass.  The snowpack structure remains problematic on the northern half of the compass with buried weak layers up to several feet deep or more.  Although feedback and triggered avalanches are becoming less common on the shady side, the size remains dangerous.  

Avalanche problems

  • Persistent Slabs

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

    Weak facets, depth hoar, or collapsible crusts are widespread on the northern half of the compass and on some sunnier aspects at high elevations.  Slabs on top of these weak layers average 2 to 3 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, trees, 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.  

    Several large to very large persistent slab avalanches on Mt. Baldy that ran sometime in the past 10 days.  

  • Wet Slabs

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

    As meltwater drains into the snowpack, it can weaken the bonds of buried facets or depth hoar layers and cause natural or triggered wet slabs.  Be cautious of steep, sunbaked slopes as temperatures increase later in the day and the upper snowpack gets saturated.  You can avoid the problem by traveling early in the day while the snow surface is still frozen or by moving to cold, shady aspects.  

    A wet slab that ran on 2/27 on a southwest aspect above treeline. 

  • Loose Wet

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

    As the snow surface gets wet and loses cohesion on sun-warmed slopes, watch for natural or triggered point-release avalanches in the upper snowpack.  These can be dangerous if they push you into trees, rocks, or gain volume in long gullies. A few could trigger larger slab avalanches.  Look for rollerballs, pinwheels, or ankle-deep wet snow to identify the problem.  You can avoid the problem by moving to slope angles less than 35 degrees or to colder aspects where the snow surface is frozen.  

    A long running wet loose avalanche from earlier this week.  

Avalanche Discussion

Recent fieldwork, the significant downturn in persistent slab avalanches, the lack of snowfall or significant windloading in the past 10 days, and the extent of surface crusts in the morning point toward Moderate danger at the start of the day in both forecast zones.  The big question is how much will this warmup increase the danger?  This isn't the first "heat shock" on the snowpack, but it is the hottest one.  Yesterday, we observed one large wet slab release and a few wet loose avalanches.  Temperatures are significantly warmer this morning (15 to 20 degrees) and will rise about 5 degrees higher today. This means meltwater will make a much bigger run at our buried weak layers on the southern half of the compass.  We expect wet slabs to become larger and more frequent today, thus the rising danger.  This week, our small sample of wet slabs is concentrated to southerly aspects near and above treeline.  Shoulder aspects (east and west) at low to mid elevations are also suspect because not all of them have seen meltwater through the snowpack yet.  At our CB elevations, the north half of the compass should remain mostly dry thanks to late February sun angles and effective radiative cooling under clear skies.  

If you're late to the party, you can go to northerly aspects to avoid wet slab concerns.  Of course, you still face the same dragon we've been fighting for weeks.  This stability test from Queen Basin yesterday sums up the persistent slab situation pretty well:  hard to trigger but dangerous if you do.  The only fail-proof weapon for slaying that dragon is slope angles. Otherwise, slopes with deeper and more uniform snowpacks, or those where the slab recently flushed offer lower risk of poking the slumbering beast.   This very large avalanche (looker's right side of photo) on Mt. Baldy is alarming. We don't know when it ran, but I'd be wary of traveling below slopes like this with overhanging and heating cornices today.  

Regions covered