Avalanche Forecast

Issued: Jan 17th, 2014 8:46AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Wind Slabs, Persistent Slabs and Cornices.

Avalanche Canada bcorrigan, Avalanche Canada

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Overnight: Temperatures are expected to rise overnight at higher elevations, and drop down to close to freezing at 1600 metres. Upper elevation winds should be moderate South Westerlies Saturday: Clear, sunny, and very warm in the alpine with light Westerly winds. Expect +5 degrees in the alpine with strong solar radiation.Sunday: .Temperatures begin to cool down late Sunday with variable light winds. Freezing level around 1400m.

Avalanche Summary

1 size 2.5  snowmobile triggered avalanche in steep shallow snowpack, also several size 2 natural avalanches in the past 24 to 48 hrs. and ,most likely triggered by radiation heating, failing to near ground level. Areas of shallow snowpack are of special concern, as well as areas where there is a hazard from above such as cornices or steep south facing cliffs.

Snowpack Summary

Expect extensive wind transport and wind slab development in all areas of the region. Recent storm snow varies from 40-70 cm across the region and I suspect that in some alpine areas storm snow has been transported into slabs that are more than a metre thick. Persistent weak layers of buried crusts/facets/surface hoar continue to be a concern, and may have been the failure plane for recent large natural avalanches. Forecast very warm temperatures may result in loose wet avalanches or cornice falls that may trigger the persistent weak layers or the basal depth hoar. Strong solar radiation combined with above freezing temperatures in the alpine could create very touchy triggering on Southerly aspects.

Problems

Wind Slabs

An icon showing Wind Slabs
Strong winds have created hard wind slabs in the alpine and at tree line, very warm temperatures and strong solar radiation may increase the likelihood of triggering. A cornice failure or radiation sloughing in cliffs may trigger lower slopes.
Be careful with wind loaded pockets, especially near ridge crests and roll-overs.>Watch for areas of hard wind slab in steep alpine features.>Watch for areas of hard wind slab in steep alpine features.>Be careful with wind loaded pockets, especially near ridge crests and roll-overs.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
Recent storm snow and hard wind slabs have been added to the load above buried weak layers. Deeply buried weak layers may become harder to trigger, but the consequences are very large destructive avalanches.
Be aware of the potential for large, deep avalanches due to the presence of buried facet/crust layer and depth hoar layer.>Be aware of the potential for large, deep avalanches due to the presence of buried facet/crust layer and depth hoar layer.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Cornices

An icon showing Cornices
Cornices may become weak and fall off naturally due to strong solar radiation and forecast warm alpine temperatures. Cornice falls are a large load that may release buried persistent weak layers on slopes below, resulting in very large avalanches.
Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Cornices become weak with daytime heating. >Cornices become weak with daytime heating. >Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Jan 18th, 2014 2:00PM

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