Avalanche forecast

Southeast Mountains

Crested Butte Avalanche Center
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Avalanche danger

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

The warming trend continues.  Wet avalanche concerns are spreading to include more aspects and elevation bands as temperatures rise; there could be a few natural wet avalanches today.  Carefully monitor surface conditions where you find wet surface snow.  If you find more than a few inches of wet snow, then move to a cooler aspect or lower angle terrain.  A chance remains for you to trigger a slab avalanche on slopes facing the north half of the compass.  These slabs could be thinner from recent northerly winds or break several feet deep on a well-developed weak layer. 

Avalanche problems

  • Persistent Slabs

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

    On the northern half of the compass, you can trigger a slab avalanche that breaks up to several feet thick on weak faceted snow that was buried last month. Slabs can be triggered remotely from below or adjacent slopes.  Collapsing and cracking are clear signs of instability, although direct feedback on this problem has become less frequent.  In the Southeast Mountains, slopes holding a snowpack deeper than 1 meter and less than 2.5 meters are most suspect.  When in doubt, head for lower consequence terrain, or slope angles in the lower 30-degree range and less.

    This large persistent slab avalanche was remotely triggered on 3/18. 

  • Loose Wet

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

    We are two days into a prolonged warm-up.  Warm temperatures and a strong, spring sun will weaken the snow surface throughout the day.  Rollerballs and pinwheels are good indications that sunny slopes are past prime and can produce wet loose avalanches.  If you find more than a few inches of wet, loose snow at the surface you should move to a cooler aspect.  Step out of your skis/board, or off your machine to test foot penetration; sinking past your ankle bone is a good indication you can trigger a wet avalanche.  You can use small test slopes or ski cuts to test conditions before committing.  Expect east and south slopes to warm up first followed by westerly terrain later in the day.  As liquid water moves into the snowpack, there is a  small chance that you could trigger a Wet Slab avalanche, particularly on high elevation southerly slopes or on west and east aspects at all elevations.  These places have dry weak layers and/or crusts that could, in isolated areas, produce Wet Slabs.

    3/24 - A wet avalanche that ran yesterday.  This looks large enough to be dangerous.  Rocky terrain like this often produces wet avalanches sooner than you would expect.

Avalanche Discussion

Overnight low temperatures and daytime high temperatures are on the increase.  Expect a noticeable increase in the hazard from wet avalanches today, and anticipate conditions to worsen through the weekend.  In addition to wet problems, the Persistent Slab problem lingers on northerly-facing slopes and presents you with a less-likely, but real possibility of triggering a dangerous slab avalanche.  The snowpack does not tolerate rapid changes, and we are entering a transitional period where conditions could produce a few surprising avalanches.

Wet Avalanches: Overnight low temperatures increased by around 5-8 degrees compared to the previous night.  The overnight freeze was good last night, but expect things to warm up more quickly today as compared to yesterday.  The most likely wet avalanche problem for you encounter today will be Wet Loose.  Most slopes on the south half of the compass will soften and wet today, and there's even a chance for low elevation northerlies to become wet at the surface.  Some sunny slopes may weaken enough that loose avalanches could entrain a dangerous amount of volume and harm you.  Be mindful of areas that are protected from the wind and surrounded by rocky terrain as these terrain characteristics often warm faster and produce the most liquid water.  You can take a look at this observation from Mount Emmons yesterday, but expect conditions to worsen today.

As liquid water drains through the snowpack, it can pool on crusts or saturate persistent weak layers, and create a Wet Slab avalanche hazard.  Yesterday, observers noted liquid water was nearing the February "sandbox" facet layer below treeline on east-facing slopes.  This evidence suggests that Wet Slabs could pose a small threat today, particularly on east and west aspects where the February "sandbox" layer is about to be flooded with water.  Predicting Wet Slabs is very uncertain, but we do understand that liquid water flooding buried persistent weak layers is the critical factor for it to be a possibility.  Your best defense against Wet Slabs is similar to Wet Loose avalanches; time your travel so that the surface has softened just enough for quality riding but not a sloppy mess.  Wet Slabs are more likely to occur on slopes with vegetation or rocks as these features can accelerate meltwater production.  Start early and finish early.  Expect the potential for Wet Slabs to increase this weekend as overnight freezes become poor and high temperatures increase.

Persistent Slab:  Due to the potentially large and dangerous size, and the inherent, unpredictable behavior, this remains a hazard today.  Slabs have the potential to break several feet thick on weak layers buried in mid-February.  We are now more than 10 days out since our last notable loading event ended, and the likelihood of triggering a persistent slab is decreasing.  In the Northwest Mountains, we've lowered the likelihood of persistent slabs to "unlikely".  In general, the snowpack is deeper and weak layers are improving faster in the snow-favored zone.  There are always exceptions, especially in wind-affected alpine terrain. Given the potential size and variability near and above treeline, our travel advice remains consistent with Moderate danger.   Near the boundary of our two zones, and in the Southeast Mountains, collapses, shooting cracks, and unstable pit results have continued relentlessly since our weak layers were first buried.  Slabs are a bit thinner, weak layers are weaker, and human triggering remains possible on slopes that didn't already avalanche during the late February cycle.  Some northerly slopes may become wet at the surface and could produce loose avalanches which can act as a trigger for larger Persistent Slab avalanches.

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