Avalog Join
Archived

Avalanche Forecast

Mar 21st, 2013–Mar 22nd, 2013
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
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
1: Low
The avalanche danger rating below treeline will be low

Regions: Purcells.

Periods of strong solar radiation may weaken and release storm slabs on Southerly aspects where a buried crust may act as a good sliding surface. Cornices may also fall off due to solar warming.

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Friday

Weather Forecast

Overnight and Friday: Unsettled convective weather is forecast to bring a few more cms of snow overnight and during the day. Amounts may be slightly enhanced in some of the up-slope areas. Alpine temperatures should drop to -14.0 overnight and the freezing level is expected to rise to about 900 metre during the day. Moderate Northwest winds should become light Northerly with moderate gusts.Saturday: A ridge of High pressure is slowly moving into the interior regions from the coast. Cloudy conditions in the morning should clear gradually during the day. There is a chance of a few flurries in the morning. Freezing levels are expected to rise to 1000 metres under clearing skies. Sunday: The ridge of High pressure is expected to continue to bring mostly clear skies and light Northerly winds to the interior ranges. Overnight alpine temperatures are forecast to be about -13.0 with the freezing level rising to 900 metres during the day. Periods of strong solar radiation are expected.

Avalanche Summary

Explosives control released storm slab avalanches that were 50-70 cms deep and up to size 2.5. Some reports of skiers controlling soft slab avalanches up to size 1.0 from immediate lee terrain features.

Snowpack Summary

The new storm slab is about 30-50 cms deep, with wind transported pockets that are about 70 cms deep. New cornice growth is reported to be poorly bonded and breaks off easily with light triggers. A weak layer of surface hoar and/or a crust is buried down about 70-120 cms in the alpine and treeline elevations. This surface hoar layer is producing variable results in snow profile tests, and continues to be a concern for professionals.

Avalanche Problems

Storm Slabs

New storm slabs may take a couple of days to settle and bond to the old surfaces. Periods of strong solar radiation may release the storm slab where it is sitting on a buried crust.
The new snow will require several days to settle and stabilize.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Persistent Slabs

Storm snow, wind loading or cornice fall may overload a persistent weakness buried in the upper snowpack. This could lead to surprisingly large avalanches.
Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 3 - 6