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Archived

Avalanche Forecast

Mar 23rd, 2016–Mar 24th, 2016
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
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
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 Columbia.

New snow and strong winds overnight will increase the avalanche danger. New snow may release as loose wet avalanches when temperatures rise during the day.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain on Thursday

Weather Forecast

10-20 cm of new snow overnight with higher amounts possible in western upslope areas. Freezing levels staying above 1300 metres with moderate to strong southwest winds. Another 5-10 cm of snow during the day on Thursday as freezing levels rise up to 1500 metres with moderate westerly winds. Some convective flurries on Friday morning with a freeze down to at least 1000 metres. Becoming mostly sunny during the day on Friday with light northwest winds and freezing levels climbing up to 1700 metres. Freezing down to 1000 metres by Saturday morning, with a mix of sun and cloud during the day.

Avalanche Summary

No new reports of persistent slab avalanches on Monday or Tuesday. Loose wet solar induced activity in most areas up to size to size 2.0, as well as some thin wind slabs in the high alpine on shaded aspects. On Sunday we had reports of natural cornice falls up to size 3.0 that triggered persistent slab avalanches on the slopes below, and solar triggered persistent slab avalanches up to size 2.5 in the alpine from slopes steeper than 40 degrees. On Saturday cornice fall produced avalanches to size 3 on north and northeast facing features between 2000 and 2400 m, failing on the late February persistent weak layer. Small natural storm and wind slabs were also reported on northwest, northeast and east facing slopes between 2100 and 2400 m.

Snowpack Summary

Forecast new snow and wind is expected to develop new storm slabs above a mix of surfaces, including crusts on solar aspects, moist snow up to treeline, and dry snow or recent wind slabs in the alpine on shaded aspects. Cornices continue to be described as large and fragile. The late February persistent weak layer is an aspect dependant mix of surface hoar, facets and/or a thick crust down around 60 to 110 cm below the snow surface. Commercial operators continue to see hard sudden planar results in snowpack tests, which suggests that wide fracture propagations are possible. New storm loading above the buried persistent weak layer may increase the likelihood of triggering large avalanches.

Avalanche Problems

Storm Slabs

Forecast new snow and wind are expected to develop new storm slabs at all elevations. Moist snow below treeline may release as loose wet avalanches during daytime heating.
Avoid freshly wind loaded features.>Be alert to conditions that change with elevation.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 4

Persistent Slabs

Sudden planar results in snowpack tests suggest that triggering this layer may result in wide fracture propagations and large avalanches. Avoid convex un-supported terrain features.
Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Use conservative route selection, stick to moderate angled terrain with low consequence.>Choose well supported terrain without convexities.>Avoid slopes with glide cracks.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 3 - 6

Cornices

Cloud cover and reduced solar may reduce likelihood, but forecast new snow and wind may increase the load on fragile cornice structures. Avoid slopes below cornices and chutes with corniced entrances.
Do not travel on slopes that are exposed to cornices overhead.>Extra caution needed around cornices with current conditions.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 3 - 5