Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

As the day warms up, expect to encounter wet avalanche activity on steep, sunny slopes. We aren't certain exactly how much avalanche activity will result, but if and when you see rollerballs or small slides running, avoid traveling on or below similar slopes and retreat to shadier aspects. At mid and upper elevations you might still be able to trigger a shallow slab avalanche on steep features. 

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Freezing levels will rise to 9000ft Tuesday afternoon, which will probably mean a spike in wet loose avalanche activity during the day. Partly cloudy skies with increasing afternoon sky cover and the weak December sun leaves us with uncertainties about how much avalanche activity will actually occur. That being said, wet loose avalanches are some of the easiest type of avalanches to predict and manage.

    Rollerballs are sometimes precursors to wet loose avalanches. If you see rollerballs, and especially if you see new or active wet loose avalanches, avoid traveling on steep aspects or the lower angle terrain beneath the steep slopes. Snow that was previously light, dry powder usually surprises us the most, as it doesn't take much warming and moistening before rollerballs and then small wet loose avalanches begin running in the shallow surface layers. We expect any activity to run in the new snow layer, probably 6 inches deep or less. 

    Slopes may not be reactive first thing in the morning, but as the day warms up, or if more sun patches appear, wet activity could increase. Expect more easterly aspects to moisten in the morning, before shifting south, and then more westerly in the afternoon. Avalanches also tend to first run near rocky patches and cliff bands, or they could possibly be initiated from snow falling out of trees. 

    Example photo: Wet loose avalanches running from steep, rocky features, similar to what you might see on Tuesday. 

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    We received just over a foot of new snow Saturday night, and avalanche activity likely peaked early Sunday morning. At mid and upper elevations, it's possible that you could still find and trigger an avalanche in steep locations. Very little wind occurred during and after the storm, but in some areas, especially at upper elevations where we have minimal information, you might find a subtly stiffer pocket of snow that you could trigger an avalanche in. Any slabs will likely be about 6 inches deep. 

    If you do trigger a slab avalanche, it may be hard to identify beforehand as the slab could be so soft. However, especially at upper elevations you might see subtle wind sculpted features as good indicators of slab formation. If you enter steep terrain with loose, dry snow, you could initiate a sluff, or dry loose avalanche. Any loose dry avalanches will likely remain small, but pay attention to your surroundings if you enter steep terrain. These avalanches will usually fan out below you, but if you're not paying attention and get ahead of it, one could hit you from behind. 

    If you enter steep terrain on Tuesday, expect that a small slab or sluff could result, and have an exit plan or strategy so that if you do trigger one of these avalanches, it won't take you for a scary ride. In particular, if you're above terrain traps such as a gully, a cliff, trees or boulders, make sure you've got an escape plan so you don't get buried deep in  a gully, taken off a cliff or dragged through objects. 

    Example photo: A shallow slab avalanche similar to one that you might be able to trigger on Tuesday. 

Avalanche Discussion

Snow that fell Saturday night mainly appears to be well bonded to the underlying crust. The crust formed from the rain that fell in the day before the snowfall began. Under the crust, moist, consolidated snow exists. Most of our avalanche concerns lie within the new snow layer above the crust. 

Observations are limited this time of year. We have very little information from upper elevations, in particular. Help us write a better forecast by sharing an observation if you get out in the backcountry. 

Regioni coperte