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Archived

Avalanche Forecast

Jan 8th, 2019–Jan 10th, 2019
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
The bottom line: Snowfall and strong winds will stress an already weak snowpack. You can easily trigger large avalanches on wind loaded slopes. If you see fresh avalanches or experience collapses or cracks in the snow, avoid all slopes 35 degrees and steeper.

Avalanche Problems

Wind Slabs

Another round of snowfall and very strong winds will build fresh wind slabs on Wednesday. Winds may blow snow further down slopes than you expect. Variable wind directions will continue to redistribute snow in complex ways. You are most likely to find wind slabs just below ridgelines, and on the sides of cross-loaded gullies on open slopes. Look for wind-driven snow, fresh cornices, and snow drifts to indicate wind slabs may be nearby. Use wind stripped areas, ridgelines, and lower angled slopes to avoid triggering wind slabs as you travel.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 2 - 3

Persistent Slabs

Buried surface hoar that formed around Christmas will be tested again by an added load of new snow and wind. This weak layer can be found 1-2ft below the snow surface. It is mainly a concern above 6000ft. Numerous avalanches occurred on this layer in the past week. These avalanches were impressive and broke widely across terrain features. Be suspect of steep, open slopes at upper elevations. Watch for shooting cracks, collapses, recent avalanches, and sudden results in snowpack tests. These are warnings you are in terrain where you can trigger an avalanche on this layer. The absence of a melt-freeze crust in the upper snowpack is another good indication you are high enough in elevation to find the buried surface hoar layer intact. The surface hoar is much less of a concern at lower elevations where water recently percolated through much of the upper snowpack.

In areas further east, you will find a shallower snowpack with weak snow near the ground. This poor snowpack structure warrants respect. If a layer near the ground failed, it could produce a dangerous avalanche involving the entire snowpack. Be especially cautious of steep rocky terrain and unsupported slopes on the eastern edge of the range.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 3 - 4