Avalanche Forecast

Issued: Jan 10th, 2014 7:45AM

The alpine rating is high, the treeline rating is high, and the below treeline rating is considerable. Known problems include Storm Slabs and Persistent Slabs.

Peter, Avalanche Canada

South Columbia.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Overnight and Saturday: Heavy snow – around 15-20 cm by morning and another 20 cm on Saturday. Winds are strong from the S-SW. The freezing level may jump to around 1500 m briefly before dropping slightly on Saturday.Sunday: Moderate to locally heavy snowfall continues – 15-20 cm. The freezing level should be around 500-800 m and winds are strong from the W-NW. Monday: Periods of snow. The freezing level should jump to around 1500 m and winds remain strong and gusty from the W-NW.

Avalanche Summary

On Friday morning fresh storm slabs, 20-30 cm thick, were easily triggered on moderately steep terrain and were propagating quite far. It's likely that some areas experienced a natural avalanche cycle on Friday. The size and likelihood of avalanches is certainly on the rise through the weekend. Buried persistent weaknesses may also become reactive with heavy loading from snow and wind. Be aware of what is above you. Very large avalanches running full path are possible.

Snowpack Summary

Another 20-30 cm of snow fell on Thursday night bringing a total of around 50 cm of storm snow sitting on a variety of snow surfaces ranging from older stiff wind slab, a soft layer of facetted snow and/or surface hoar. 70-90cm below the surface from you may find at various depths a thin melt freeze crust below 2100m and a couple of buried weak layers (surface hoar, facetted snow, and/or a crust) that continue to be reactive in snowpack tests.There are two deeper layers of note. The late-November persistent weak layer consists of a sun crust on steep south facing slopes and surface hoar in sheltered areas and is now buried 90-160cm below the surface. The October deep persistent weak layer consists of a layer of facets sitting on a crust at the base of the snowpack. This layer is predominantly found on northerly aspects at treeline and in the alpine. The depth of both these layers makes directly triggering an avalanche on them unlikely (maybe a heavy load on a thin spot in steep terrain). Their presence could, however, increase the size of a potential avalanche through step-down.

Problems

Storm Slabs

Some areas could receive 50 cm of new snow by the end of the weekend. Strong W-SW winds may also form deep and touchy wind slabs in exposed lee terrain.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Stick to simple terrain and be aware of what is above you at all times.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 5

Persistent Slabs

The presence of persistent weak layers increases the likelihood of larger avalanches that could release to a depth of a meter or even more.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Jan 11th, 2014 2:00PM