Lawinenlagebericht

Southeast Mountains

Crested Butte Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

Our warming trend continues to increase wet avalanche hazards.  The threat of natural and triggered wet avalanches will increase as the day warms up. Start and finish your tours early or move to colder aspects or mellower terrain before surface crusts thaw into wet mush.   A handful of wet avalanches ran yesterday.  Last night's weaker freeze and today's warmer temperatures could spur larger and/or more widespread activity.   A lingering chance remains for you to trigger a large slab avalanche on slopes facing the north half of the compass.  

Lawinenprobleme

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    We are three days into a prolonged warm-up.  Warm temperatures and a strong, spring sun will cause surface crusts to thaw throughout the day or moisten previously dry snow, making natural and triggered wet loose avalanches a concern in steep terrain.  Rollerballs, pinwheels, or ankle-deep slushy snow are good indications that sun-baked slopes are past prime.  Move to a colder aspect or lower angle terrain to avoid this problem once it develops.  Wet loose avalanches are most dangerous if they push you into trees, over cliffs, or down gullies.  With a fairly weak overnight freeze, expect easterly aspects to thaw quickly this morning, followed by southerly then westerly terrain as the day progresses.   

    3/25: Natural wet loose avalanches on an east-facing slope in the Beckwith Range.  

  • Wet Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Consecutive days of meltwater production are increasing our concerns for natural or triggered wet slabs.  As meltwater drains into weak layers, it can compromise their strength and cause a dangerous wet slab to release.  Our most concerning aspects are where our mid-winter weak layers are transitioning from dry to wet this weekend: starting with east and west aspects at mid to low elevations.  There is a smaller chance that wet slabs could also release on higher elevation southerly aspects as well.  Travel on these aspects while surface crusts are stout and supportive.  Once you feel your skis or machine starting to punch through softening crusts, it's time to move to mellower slope angles.   

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    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. 

Avalanche Discussion

Overnight low temperatures dropped below freezing for a few hours under clear skies, which will provide enough surface cooling for a moderate surface refreeze early this morning.  On sunnier aspects, that will provide a window of stable conditions this morning that deteriorates towards increasingly dangerous wet avalanche hazards as the day progresses.  The hazard will increase first on easterly aspects and follow the sun around to the south and then west aspects later in the day.  If you're skiing or riding corn snow today, time your exit from steep terrain while only the top few inches of snow is wet, and before crusts become unsupportive to your weight.  If you're hunting for softer, mushier snow on your snowmobile, choose smaller terrain features or lower angle slopes later in the day once crusts soften. 

So far, wet avalanche activity with this warm-up has been relatively small and localized to specific terrain features: very steep and rocky terrain.  We're expecting that to start to change either later today or tomorrow as the meltdown continues to escalate with weaker freezes and higher temperatures.  Given the lack of any indicator wet slabs or large gouging wet loose avalanches thus far, we have a fair amount of forecaster uncertainty regarding the timing of dangerous conditions this weekend.  A few things we are confident about though:  1) The trend is getting worse; today will be more dangerous than yesterday, and tomorrow will be worse than today.  2) If wet slabs start releasing, they have the potential to be large in size.  3) You can easily recognize when conditions are becoming unstable by monitoring surface conditions and exiting steep terrain before it produces rollerballs, pinwheels, or unsupportive/trenchy wet snow.

Our primary concerns are shifting towards wet avalanches, but don't forget that northerly aspects are staying dry or only seeing surface moistening right now.  Our dryspell weak layers are still lurking several feet deep and there is still a chance that you can trigger a large persistent slab, especially in the shallower parts of our forecast area.  There's also some concern for cornice falls to act as natural triggers where these issues overlap.  

 

 

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