Lawinenlagebericht

Gunnison

Crested Butte Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

A mediocre refreeze last night and sunshine during the first half of Monday will keep wet avalanche problems on the menu.  Start and finish your day early or move to less consequential terrain once the snow surface starts to rollerball, pinwheel, or thaws to more than ankle-deep wet snow.  Old slabs have become increasingly rare but remain an isolated threat on high, northerly aspects, especially on rocky or shallow slopes. 

Lawinenprobleme

  • Wet Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–2.5

    There's a small chance for natural or triggered wet slab activity today.  The above-normal temperatures are causing meltwater to flow deeper into the snowpack towards old weak layers.  Meltwater can cause weak layers to fail, resulting in surprisingly large wet avalanches.  Although predicting the timing and location of wet slabs is difficult, you can reduce your risk by traveling early in the day while snow surfaces are still frozen or just starting to soften.  Move to colder aspects or lower angle slopes if you are sinking more than a few inches into a wet snowpack.   High-elevation, north aspects do not have enough meltwater for this problem to develop yet, and low-elevation southerly aspects have already seen water drain through the snowpack, reducing the threat.  

  • Loose Wet

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

    Watch for shallow sluffs in the upper snowpack as it gets wet from solar radiation and warming temperatures.  Instabilities will be easy to recognize: look for rollerballs, pinwheels, or sluffing from very steep slopes.  Use sluff management techniques or move to lower slope angles to manage the problem if it develops.  Even though most wet sluffs today are expected to be relatively small, they can pack enough punch to carry you down a gulley, over a cliff, or into trees. In isolated areas, a wet slide might gather enough volume to be large.  You can avoid the issue by moving to colder aspects where the snow surface is still frozen or just starting to thaw.  An incoming storm will bring colder air and cold cover around midday.  Once this happens, the threat of wet avalanches will slowly diminish by the afternoon as surfaces refreeze.

    One of the larger wet loose avalanches observed this week.  Note how the longer and steeper the terrain is, the more snow it entrains.  

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1.5–2.5

    High-consequence persistent slab avalanches have become isolated and difficult to trigger.  The most recent Persistent slab avalanche was observed on 4/14 near Avery Peak before that was 4/3 on Mount Whetstone.  The most problematic terrain is on high elevation, northerly aspects in areas with relatively shallow snowpacks (<175 cm).  Old facet layers are weaker and easier to impact in steep rocky slopes with variable snow depths.   This video highlights this type of terrain. 

    (4/14/2024) A recent Persistent Slab on a northwest aspect near Avery Peak.  

    Photo: Crested Butte Avalanche Center

Avalanche Discussion

Sunday was likely the warmest day of spring so far.  Most locations received a mediocre freeze thanks to warm overnight temperatures.  Clear skies helped freeze that snowpack due to radiational cooling.  Sunny skies during the first half of the day will keep wet avalanche threats on the problem list for another day however incoming cloud cover and a cold front will bring a decrease to these issues late on Monday.

To manage wet avalanche issues start your day early and exit steep terrain early.  Carefully keep track of surface crusts and the volume of wet snow at the surface.  Once you begin to sink past your ankles in the wet snow, it's time to find a cooler aspect or head for lower-angled terrain.  You are most likely to encounter Wet Loose avalanche issues, but given the significant amount of meltwater moving through the snowpack, Wet Slab avalanches may be possible on Monday.  Watch this video from a few days ago describing a wet snowpack and how to manage the current wet avalanche problems.

An observer reported a fresh Persistent Slab on a northwest aspect near Avery Peak.  It is difficult to say if this was a Wet Slab or a hot Persistent Slab avalanche that was released due to a shallow loose avalanche.  It reinforces that there could be a few isolated places on upper-elevation northerly slopes where you can trigger a large slab avalanche.

Once cloud cover and the cold front arrive around midday, expect wet avalanche concerns to slowly ease during the rest of the day as snow surfaces refreeze.  By Tuesday morning, storm snow avalanche problems could be on the problem list if the weather forecast verifies so be prepared for a return to winter-like conditions tomorrow.

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