Archived

Avalanche Forecast

Mar 28th, 2013–Mar 29th, 2013

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

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

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: Northwest Coastal.

Large natural and human-triggered avalanches have occurred on a persistent weakness buried on March 9th. Continued reactivity is expected on this layer throughout the weekend.

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 2400m on Sunday.

Avalanche Summary

Natural slab avalanches up to 2.5 have been reported, likely failing on the March 9th layer. Loose wet sluffs up to 2.0 have also been reported. As well, a recent size 2.5 slab avalanche was remotely triggered by a skier in the Hidden Lake area near Shames. Once again, the March 9 surface hoar layer was the culprit. Nobody was caught in the slide.

Snowpack Summary

Recent snow has settled with the influence of warm temperatures and surface hoar is growing on shaded slopes. Solar aspects and lower elevation terrain are now well into a daily melt-freeze cycle. Wind slabs may be found at alpine and treeline elevations on many aspects due to variable winds. Between 50-75cm below the surface is layer of surface hoar buried on March 9th which is variably reactive. In some areas it is stubborn and requires a significant trigger, while in other areas the layer is well preserved and primed for human triggering with the potential for very large avalanches. Check out the Forecaster's Blog for related discussion. The mid snowpack is generally well settled and strong. Cornices are large and untrustworthy, especially when the sun is out.

Avalanche Problems

Persistent Slabs

In some areas the March 9th layer can be triggered from a distance, propagate across large distances and create surprisingly large avalanches.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Choose well supported terrain without convexities.>Avoid areas with overhead hazard.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 6

Loose Wet

Expect loose wet sluffs to trigger in the afternoon when the sun is at its strongest.

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 developed cornices loom over slopes. Forecast warming will increase the chances of failure with the potential to initiate large avalanches failing on the March 09 persistent weak layer.

Cornices become weak with daytime heating, so travel early on exposed slopes.>

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 6