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Archived

Avalanche Forecast

Apr 14th, 2017–Apr 15th, 2017
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
1: Low
The avalanche danger rating at treeline will be low
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
1: Low
The avalanche danger rating at treeline will be low
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
1: Low
The avalanche danger rating at treeline will be low
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Little Yoho.

West winds have created touchy new windslabs. There is the potential for more snow Saturday. This, coupled with increasing winds will raise the hazard this weekend.

Weather Forecast

West winds will continue to build late Friday reaching strong values midday Saturday before diminishing Sunday. Up to 15cm of precip is in the forecast for the 93N with less further South for Saturday. Freezing levels look to stay around 1500m for Saturday but will creep higher Sunday and higher still Monday with increasing solar influence.

Snowpack Summary

Small amounts of snow over this past week have added up to about 20-40cm that moderate west winds redistributed Thursday night. A new crust formed to 2300m on North aspects late Thursday and much higher on sunny slopes. At treeline and above, the midpack is a 120cm+ firm slab with few weaknesses overlying weaker basal facets in much of the region.

Avalanche Summary

Late day heating Thursday may have triggered two sz 2.5 storm slabs near the Lake Louise resort 60cm x 100m wide. West winds overnight resulted in several skier triggered windslabs propagating up to 100m wide in the alpine. Skiers deliberately triggered a sz 2 windslab at the top of the North gulley on Mt Cathedral.

Confidence

Intensity of incoming weather systems is uncertain on Saturday

Avalanche Problems

Persistent Slabs

The snowpack is gaining strength, however the facets deeper in the snowpack remain a concern in thin alpine areas and where a cornice could trigger the slope. These facets do exist in isolated treeline areas, but are not currently a problem.

  • Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.
  • Choose the deepest and strongest snowpack areas on your run.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Unlikely - Possible

Expected Size: 2 - 4

Cornices

West winds will add fragile new growth to the mature cornices that exist throughout the range. These are a fall hazard while traveling on ridges and a significant overheard hazard to travelers below them. Wind, warm temps or sun may cause failures.

  • Pay attention to overhead hazards like cornices which could trigger slabs.
  • Give cornices a wide berth when travelling on or below ridges.

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

Elevations: Alpine.

Likelihood: Likely

Expected Size: 1 - 3

Wind Slabs

Up to 40cm of recent snow has been available to transport by West winds. Skiers could easily trigger windslabs local to ridges Friday. With more wind and more snow in the forecast, expect these slabs to remain touchy through Sunday.

  • If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
  • Minimize overhead exposure during periods of heavy loading from new snow, wind.

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

Elevations: Alpine.

Likelihood: Likely - Very Likely

Expected Size: 1 - 3