Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Strong ridgetop winds should easily transport the new snow into shallow but reactive wind slabs. Look for signs of instability as you gain elevation and enter open areas exposed to drifting. The more new snow you find, the more able you are to trigger an avalanche on steep slopes.

Problemi valanghivi

  • Wind Slabs

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

    With the incoming system, any new snow with increasing winds will easily transport and could form some very shallow but reactive slabs late in the day. , especially in consequential terrain.New snow over weak surfaces or slick crust is likely to create isolated areas where you could trigger a slab on Saturday. You're most likely to find thicker and reactive slabs near and above treeline, where westerly winds into Saturday morning may redistribute the newly fallen snow. Make sure to observe how wind-drifted snow reacts before committing to steep slopes or larger features. You can check to see how the new snow is reacting with hand pits, skin track tests, and small test slopes. Look for shooting cracks and small slabs as indicators that you could trigger an avalanche.

    Less snow is expected in the eastern portin of the zone, so you may find locally lower danger there. 

    (12/30/2022)

    Example of long shooting cracks in a fresh wind slab. These long cracks are bullseye information of unstable snow.

    Photo: Rob Pollard

Avalanche Discussion

The mid winter dry spell has come to a close, and the mountains are picking up some new snow once again. The longer the dry spell, often the less likely the new snow is to bond well to old surfaces. We're not sure yet how this new snow will react yet, but chances are it won't bond well. Previous snow surfaces were a wide range of conditions including small near surface facets on sheltered and northerly slopes, slick sun crusts on slopes that receive direct sun, and various degrees of stiff wind packed snow. Some areas held isolated patches of recently buried surface hoar on shaded slopes. Lower elevations generally hold firm and icy crusts. 

Katie found a recent, very small wind slab right beneath a cornice on Thursday before any new snow had fallen. This was on an east aspect at 6,600ft (see photo). See my observation from the NW side of Cannon Mountain on Feb 1 for an overview of what I found there. 

The last significant storm (and resulting avalanche cycle) in the East Central was over MLK weekend. This formed a melt-freeze crust in the snowpack, which acts as a landmark in the upper snowpack. You can find this crust 6-18" below the surface in may areas. The cold weather has weakened the snow above and below it into near crust facets. As new snow begins to add up, this creates a weak structure that we'll have to watch closely. 

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