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Archived

Avalanche Forecast

Jan 7th, 2019–Jan 8th, 2019
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Cascades - East.

The Bottom Line: Light, dry snow and gusty winds have increased the avalanche danger. The most dangerous slopes are above treeline where you can trigger avalanches that could break above and around you. You can avoid triggering these avalanches by staying off thickly-pillowed, wind loaded terrain and steering well-around wind sculpted features on slopes 35 degrees and steeper.

Avalanche Problems

Wind Slabs

With colder temperatures, moderate winds, and another shot of snow, wind slabs will be a concern at upper elevations. In locations where wind has drifted the new snow into firmer and thicker slabs, you may be able to trigger an avalanche. The new snow may be poorly bonded to a firm, refrozen crust. Use small, inconsequential test slopes to check how these slabs are bonding. 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 on nearby slopes. You can use wind stripped areas, ridgelines, and lower angled slopes to avoid triggering wind slabs as you travel.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Persistent Slabs

Folks have been consistently finding a layer of buried surface hoar from Christmas. From Mission Ridge, to Icicle Creek, to Dirty Face, its out there. You are likely to find this layer from 1 to 2 feet down from the surface. This layer is mainly a concern above 6,000ft, where the absence of a stout melt freeze crust above it may be keeping it in play. Recorded activity on this layer has been on Northerly through Southeasterly aspects. These avalanches were surprising in how widely they broke across the slopes. Be suspect of steep, open slopes at the uppermost elevations. Be observant of shooting cracks or collapsing, or the absence of a thick rain crust near the surface. At lower elevations, where water has percolated through much of the upper snowpack and has formed a stout melt freeze crust, this layer is much less of a concern. 

The further east you get, the less snow there is on the ground. Recent observations from Mission Ridge and above Mazama speak to a shallow snowpack with weak snow near the ground. This poor snowpack structure warrants respect, because if the layer near the ground failed, the avalanche could be well over 4 feet deep. Places to be cautious of in particular are where stiff slabs sit over weak snow, slopes where grass and rocks poke through with deep drifts nearby, and steep, unsupported slopes on the eastern edge of the range.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 3 - 3