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Archived

Avalanche Forecast

Jan 4th, 2015–Jan 5th, 2015
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
3: Considerable
The avalanche danger rating at treeline will be considerable
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: South Coast.

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

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 another 20-40 cm (or mm) possible. Temperatures will warm on Monday but the exact timing and extent are still a bit uncertain. Areas in the south could see the freezing level shoot above 2000 m, while northern sections hang in closer to 1000 m. 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, and it could continue throughout the day. 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 snow 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.

Avalanche Problems

Storm Slabs

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

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 6