Archived

Avalanche Forecast

Mar 28th, 2013–Mar 29th, 2013

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

2: Moderate

The avalanche danger rating below treeline will be moderate

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

2: Moderate

The avalanche danger rating below treeline will be moderate

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Northwest Inland.

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

No precipitation is expected for the forecast period. Mainly clear skies are forecast for Friday and Sunday, although high cloud is expected on Saturday.Winds will be light from the west on Friday switching to light and northwesterly on Saturday and Sunday.Freezing levels will climb steadily from 1200m on Friday to about 2200m on Sunday.

Avalanche Summary

Numerous loose wet avalanches have occurred from steeper solar aspects up to size 2.0. Size 2 cornice releases have also been noted. There was also a report of a size 2 slab avalanche which involved sun-exposed recent storm snow which reacted on a buried sun crust.

Snowpack Summary

Many parts of the region have experienced strong winds that redistributed surface snow on lee aspects creating stiff wind slabs. At lower elevations and on sun-exposed slopes, snow surfaces are well into a melt-freeze cycle.30 - 60 cm of snow overlies a crust, old wind slabs or surface hoar layer buried on March 9th. Currently, this layer seems to be less reactive, but may still be a concern in some areas (low probability-high consequence). Recent snowpack tests are showing hard, resistent shears. This layer may be healing in some places, but I would remain conservative and continue to dig and test before diving into my line. The distribution of the surface hoar is variable and it may not exist, or be reactive, in every drainage. Deeper in the snowpack, basal facets may resurface as a concern with further warming.Cornices have become well-developed and could easily become unstable during periods of warm weather or direct solar radiation. Most snow surfaces exist on solar aspects up to 2300 m, forming a melt-freeze crust overnight.

Avalanche Problems

Loose Wet

Clear sunny skies and warmer afternoon temperatures will promote deterioration within the upper snowpack. If surface snow becomes moist or wet, loose wet avalanches are likely.

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: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 4

Cornices

Large cornices will likely become weak if the sun is shining. Cornice failures may be destructive by themselves and may also initiate avalanches on the slope below.

Cornices become weak with daytime heating, so travel early on exposed slopes.>Extra caution needed around cornices with current conditions.>

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

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 1 - 6

Persistent Slabs

Spotty surface hoar buried on March 9th may be reactive in some drainages. Dig down and test layers before committing to big lines.

Carefully evaluate big terrain features by digging and testing on adjacent, safe slopes.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 5