Archived

Avalanche Forecast

Jan 21st, 2016–Jan 22nd, 2016

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

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

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

1: Low

The avalanche danger rating below treeline will be low

Regions: South Coast.

Some areas may not have seen enough precipitation to "clean out" buried persistent weaknesses. Proceed cautiously until we have a clearer picture of how conditions have changed.

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

Tonight and Friday: Rain or snow ending in the morning (10-15 mm), then cloudy with sunny breaks. The freezing level dips from 1800 m to 1400 m. Winds are moderate S easing to light from the SW. Saturday: Cloudy with sunny breaks. The freezing level is around 1000-1200 m and winds remain light from the W-SW. Sunday: Cloudy with sunny breaks. The freezing level is around 800-1000 m and winds are light from the SW.

Avalanche Summary

We will have to wait a day or two to determine how extensive the avalanche cycle on Thursday was. My guess is that we saw widespread activity at all elevations with slides up to at least size 3. Natural activity should taper off heading into the weekend. Hopefully the buried surface hoar problems were cleaned out, but I would treat any slope that did not release as being suspect, especially at treeline.

Snowpack Summary

The upper snowpack may look quite different after Thursday's storm. Expect dense new wind and storm slabs, and fresh cornice growth at upper elevations. Heavy loading from snow (and potentially rain) may have flushed-out the mid- and early-January surface hoar/facet layers that were initially buried 30-40 cm deep. However, don't rule these layers out right away. It may still be possible to trigger shallow slopes that did not release naturally. Rain has probably saturated the upper snowpack on lower elevation slopes (below 1500-1800 m), especially in the south of the region. The mid and lower snowpack is generally strong, with the exception of shallower snowpack areas that may be more faceted.

Avalanche Problems

Storm Slabs

Continued snowfall and strong winds at higher elevations will maintain high hazard in the alpine. Fresh storm slabs may fail naturally with additional loading or under the weight of a skier or snowmobile.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 4

Persistent Slabs

Heavy loading on Thursday may have tipped off a widespread avalanche cycle on the mid-January persistent weak layer; however, I would take a very conservative approach until we know the extent of this cycle and the status of this persistent weakness.

Be wary of slopes that did not previously avalanche - even on low angle terrain.>Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 2 - 5