Avalanche Forecast

Issued: Jan 4th, 2015 7:44AM

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

Avalanche Canada Peter, Avalanche Canada

Conditions are primed for natural and human triggered avalanches. Avoid all avalanche terrain and be aware of overhead hazard.

Summary

Confidence

Fair - Freezing levels are uncertain on Monday

Weather Forecast

Synopsis: Heavy precipitation and strong SW winds continue to hammer the region tonight and Monday with 25-50 mm possible. The freezing level should climb overnight from 1000 m to a little over 2000 m by Monday morning. Its hard to say how much snow will accumulate. It all depends on the timing and extent of the warming. Some areas could see rain all the way to ridge top. Precipitation and wind taper off on Tuesday but temperatures remain warm with a freezing level around 2500 m. Expect a mix of sun and cloud on Wednesday with continued warm temperatures and light winds.

Avalanche Summary

It's likely there will be a fairly large and widespread natural avalanche cycle at some point on Monday (or late Sunday), and it could continue throughout the day if heavy precipitation persists. Avoid all avalanche terrain and be aware of what is above you. Large avalanches could reach the end of run out zones.

Snowpack Summary

New snow sits on a previous variable snow surface that included wind affected surfaces (crust, hard and soft slabs), a freezing rain crust or sun crust, and surface hoar or sugary facets in sheltered shady terrain. How well the new snow bonds to this surface is the question. This storm is starting cold and will finish much warmer, meaning that the new storm snow will be more dense on top - a good recipe for slabs. Below the new we might find the mid-December surface hoar or crust/facet weak layers. These are buried between 40 and 80 cm deep on average. The surface hoar layer may be found in sheltered shady areas at and below treeline, while the crust/facet layer could be more widespread but also more variable. Reports suggest is could be between 0 and 120 cm deep depending on exposure to wind. Heavy loading in the coming days could trigger these weaknesses creating very large avalanches.

Problems

Storm Slabs

An icon showing Storm Slabs
Expect deep and dense storm slabs to build as snow piles up and temperatures rise by Monday. A natural avalanche cycle is likely and human-triggered avalanches are almost certain in steep unsupported 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

2 - 5

Persistent Slabs

An icon showing Persistent Slabs
Heavy loading from new snow, wind, and rain could overload persistent weaknesses in the top 1 m of the snowpack, leading to very large and destructive avalanches. 
Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 6

Valid until: Jan 5th, 2015 2:00PM