Lawinenlagebericht

Gunnison

Crested Butte Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 2 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Strong winds have redistributed much of the new snow, either blowing it away or blowing it into wind slabs on the lee sides of terrain featuers. These wind slabs will be the most sensitive to triggering where they formed over weak snow, on northerly-facing slopes. Also on northerly-facing slopes, there remains a low probability of triggering a large slab avalanche that fails on deeper persistent weak layers. The most concerning areas for this persistent slab avalanche problem are where the total snowpack is variable in depth due to rocky outcrops or previous wind effects. Normal caution is expected in most wind-sheltered locations, with the potential for small sluffs or storm slabs in isolated areas. 

Lawinenprobleme

  • Persistent Slabs

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

    In the last two weeks, the majority of slab avalanche activity has occurred on a layer of facets that was buried on 3/23. The last persistent slab avalanche was human-triggered on 4/3. That late March interface is now buried 2 to 5 feet deep and is gaining strength. Future avalanche concerns are transitioning away from this specific interface, and back to more isolated areas that have a weaker-than-average snowpack. Areas with a relatively shallow snowpack will have more pronounced layers of facets that have developed throughout the winter. The most common areas to find these weaker snowpacks will be steep rocky slopes with variable snowpack depths, and areas where previous winds have eroded the total snowpack depth creating large fluctuations in that snowpack depth across the terrain. This video sums up an example of this type of terrain. 

    Avalanche crowns spanning steep, rocky terrain. This avalanche ran sometime during last weekend's storm. 

  • Wind Slabs

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

    Since Friday, strong winds have blown from the south and then backed through the weekend to blow from the west and northwest. Total snow accumulations since Friday night are averaging 5 to 10 inches across the forecast area. That snow has now formed fresh wind slabs on the lee sides of ridgelines and cross-loaded terrain featuers. In many areas, those slabs have formed over hard crusts and made it easy to evaluate their potential size. These slabs will be the most sensitive to triggering where they formed over small facets on northerly facing slopes. Many of these slabs will be small in size, while some potential wind slabs could produce large avalanches in the alpine or a few areas with a notably big fetch. Wind Slabs can be avoided by sticking to sheltered or wind-scoured areas.

    An example of a small wind slab that failed below a wind-loaded ridgeline earlier this winter. 

Avalanche Discussion

Remote weather stations are not showing much for snow accumulations over the last 24 hours, despite how many snowflakes may impact your eyeballs if you were out in the mountains. Settlement in the new snow and the strong wind having blown the snow around, maybe making it difficult for those weather stations to record all the snow. What we can measure, is total snow accumulations since Friday night, coming in between 5" and 10" across the forecast area. Lake Irwin measured 1" of SWE with the Butte Snotel and Upper Taylor Snotel coming in at around .3" SWE. 

On northerly-facing slopes, you can encounter several types of avalanche problems. On steep slopes, loose snow avalanches should be expected. In a few areas that have around 8" or more of new snow, small storm slabs may also be possible to trigger. As highlighted above, wind slabs will be the most reactive on these aspects, and lastly, there are lingering concerns about persistent slab avalanches. Don't get overwhelmed by all the potential flavors of avalanche problems, and instead take note that you will need to make observations in your local area to refine how to manage the avalanche problems if you want to ride steep slopes. Keep track of how much new snow there is in the area, and look for small test slopes to see how reactive that new snow is. 

Avalanche conditions will be the easiest to manage on southerly-facing slopes. The old snow surface is a hard crust, so you can easily identify how much new snow is in the area and it will also be easier to identify where the thicker drifts or wind slabs are in the terrain. 

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