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Avalanche Forecast

Dec 5th, 2015–Dec 6th, 2015
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
4: High
The avalanche danger rating below treeline will be high
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high

Regions: South Columbia.

Saturday night's storm will elevate the hazard to HIGH on Sunday. Conservative terrain choices will be critical in the days to come.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

A series of storm systems will continue to impact the region during the forecast period. The next storm front should arrive Saturday evening and is expected to yield 20-30cm of snow by Sunday evening. Freezing levels are expected to be 1000-1400m during this period with strong SW winds in the alpine. On Sunday overnight and Monday, another 15-25cm of snow is expected in the highest snowfall areas. Winds will continue to be moderate to strong from the SW and freezing levels should be around 1500m or lower. On Tuesday, similar amounts of precipitation are being forecast but freezing levels could rise to around 2000m.

Avalanche Summary

On Friday, numerous natural and human-triggered avalanches were reported up to size 2.  Most of this activity was below treeline on a variety of aspects.  Natural and human triggered avalanche activity is expected to increase Sunday with the incoming storm Saturday night.

Snowpack Summary

Saturday night's snowfall will add to the existing 30-40 cm of recent storm snow that overlays a variety of old surfaces which include wind scoured north aspects, sugary facets, sun crusts, and/or large-sized surface hoar. The primary concern is the surface hoar which sits on top of a sun crust on solar aspects. Reports suggest that the surface hoar exists up to approximately 1800 m on all aspects.

Avalanche Problems

Storm Slabs

Expect the storm slabs in the Alpine to be most reactive in lee features. Below 1800m, expect to find 30-40cm of recent storm snow overlaying a very weak layer of surface hoar anywhere the trees are open enough to provide nice riding.
Avoid open slopes and convex rolls below treeline where buried surface hoar may be well preserved.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Avoid alpine terrain.>Avoid all avalanche terrain during periods of heavy loading from new snow and wind.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 5