Lawinenlagebericht

Central Cascades

Central Oregon Avalanche Center
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Lawinengefahr

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

Kernpunkte

Triggering avalanches in recently wind drifted snow will be likely and can result in large avalanches near treeline and above treeline. Large and destructive avalanches failing on an old snow weak layer will be possible and primarily on west, north, and east facing slopes. Avoiding slopes with wind drifts, and staying off steep, convex, and rocky areas will help to minimize your exposure to avalanches. Anytime you are uncertain about the stability of the snow, you can travel on slopes less than 30 degrees and out from under steep slopes to avoid most avalanche danger.

Lawinenprobleme

  • Wind Slabs

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

    Minimal snow will fall overnight and on Friday, however the wind speed will pick up to the upper teens to low 20's mph range during the day. There is a lot of soft snow out there available for wind transport and the forecasted winds are more than sufficent to move snow. Wind slabs will build on lee features throughout the day. Existing wind slabs can still be triggered. 

    Cracking in the wind deposited snow and recent avalanches are good indicators that you can trigger an avalanche. Wind slabs can be avoided by sticking to sheltered areas or slopes that have been scoured by the wind. 

    Wind slab avalanches have the potential to "step down" into the persistent weak layer and create much larger avalanches on west, north, and east facing slopes near treeline. 

    Overnight,  light winds will come out of the north and small wind slabs may build on the bottom half of the compass; these will be more prominent above treeline but keep an eye out for where wind loading has occured near treeline especially in the AM hours.

  • Persistent Slabs

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

    Not much has changed with this problem, except that as time goes by triggering an avalanche will become less likely. The thing that could make it more likely is a large dump of snow, but that is not in the forecast for the next week. Given the cold temperatures in the forecast, it will take time for this layer to gain strength and go away. We may be living with it for a bit. Observers have found the Jan. 31 facets throughout terrain in the given distribution (see diagram above) and is now down 2 - 3 feet below the surface. On wind loaded slopes it will be much deeper.

     Triggering an avalanche associated with the current persistent slab problem will be more likely in isolated areas. Shallow rocky areas are trigger points that can bring the weak layer closer to the surface and thereby making an avalanche more easily triggered. Steep, convex, and unsupported terrain are also places where triggering an avalanche are more likely. At a basic level, managing a persistent slab problem is easy.....avoid avalanche terrain. Triggering an avalanche on this layer will be unpredictable and therein lies the tricky nature of a persistent slab problem. The "possible" rating should not be taken likely. Triggering an avalanche on the Jan. 31 facets will result in large avalanches. Non event feedback does not mean the problem is not there. In the last few days, there have been no reports of  cracking, collapses, and whumping and we are now less likeley to get that feedback.

     It is worth digging into the snowpack to check for this weak snow on southwest and southeast facing slopes before riding in steep and consequential terrain.

     

     

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