Avalanche Forecast
Issued: Apr 14th, 2017 4:13PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Cornices and Wind Slabs.
Tim Haggarty,
Avalanche Canada
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.
Summary
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
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
Expected Size
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
Expected Size
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
Expected Size
Valid until: Apr 15th, 2017 4:00PM
