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Avalanche Forecast

Apr 10th, 2015–Apr 11th, 2015
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
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
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: Cariboos.

If alpine storm snow totals exceed 10cm, the alpine danger rating will likely rise to Considerable.

Confidence

Fair - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

FRIDAY NIGHT: 2 to 4mm of precipitation possible, less than 10cm of total snowfall expected.  Strong to extreme SW winds.SATURDAY: Freezing level hovering around 1500m.  Scattered flurries, less than 5cm of snow expected.  Moderate W/SW winds at treeline, strong W/SW winds at ridge-top.  Overcast.SUNDAY: Freezing level rising to 1500m.  Moderate W/SW winds at treeline, strong W/SW winds at ridge-top.  Overcast skies, no significant precipitation expected.MONDAY: Freezing level rising to 1800m.  Strong S winds at treeline, extreme S winds at ridge-top.  Overcast skies, no significant precipitation expected.

Avalanche Summary

A few natural cornice failures were observed Wednesday & Thursday, but slabs were only triggered in steep, unsupported rocky features and even then had minimal propagation. On Tuesday cornice failure triggered a size 3 avalanche on a North facing feature at 2700m.

Snowpack Summary

The current surface consists of surface facets and surface hoar. Below this is the 15-30cm of new snow that fell last weekend. This snow remains dry on high elevation polar aspects but has turned moist on east and west facing aspects. South facing features are moving into the spring corn cycle. Moist snow exists underneath this most recent storm snow in most of the region.Two significant persistent weak layers composed of crust and facets exist in the snowpack. Although they appear to have gone dormant for the time being, we will continue to monitor them closely. Mid-March is down 40 to 80cm below the surface and Mid-February is down 80 to 200cm. Down at the bottom of the snowpack a weak layer of basal facets exists. Large loads like cornice/ice fall or even sustained warming could initiate an avalanche on this very deeply buried weak layer.

Avalanche Problems

Wind Slabs

A relatively small amount of snow Friday night and Saturday accompanied by strong SW winds will likely result in the development of thin fresh wind slabs.  These slabs are expected to be most sensitive immediately lee of ridge-crest.
Avoid freshly wind loaded features.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Cornices

Increased winds Friday night and Saturday will add to the already large cornices that loom over many features, potentially increasing the likelihood of failure. Cornice failure has the potential to release slabs on slopes below.
Extra caution needed on slopes that are exposed to cornices overhead.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 1 - 5