Avalanche Forecast
Issued: Jan 17th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Persistent Slabs and Deep Persistent Slabs.
mark herbison,
Parks Canada
The snowpack is alive!... and is being stressed by the recent dramatic temperature swings as we transition out of the cold snap. Natural avalanche activity has started and can be expected to continue until the snowpack adjusts to the change.
Summary
Weather Forecast
Saturday will see a mix of sun and cloud with isolated snowfall amounts up to 5cm. Winds will gradually increase over the day from moderate to strong from the SW as warmer temperatures arrive. Morning lows of -25 to afternoon highs of -10. Temps and winds will continue to increase on Sunday.
Snowpack Summary
2-15cm of new snow in the past 24 hrs and sustained Southerly winds continue to build wind slabs in the alpine and open areas at tree line. There is up to 60 cm above the Dec 31 layer of facets, surface hoar and sun crust. Concern remains for the weak layers of facets and depth hoar near the base of the snowpack.
Avalanche Summary
Numerous avalanche observations and reports today across the region up to Sz 2.5. Natural cornice failures, wind slabs and persistent slabs have come alive with the recent dramatic swing in temperatures (-27 to -10 in Lake Louise today over a 6 hr period). Local ski areas seeing explosive results up to sz 2 with some stepping down to deeper layers.
Confidence
Problems
Wind Slabs
Wind slabs are forming in leeward areas from recent snowfall and moderate Southerly winds. These could be easy to trigger.
- If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
- Use caution in lee areas. Recent wind loading have created wind slabs.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
This layer may present as surface hoar, facets or sun crust. It is buried 40-80 cm throughout the region and is producing 'sudden planar' results in stability tests.
- If triggered the persistent slab may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
The potential for deeper releases on the basal layers still exist. Several large avalanches have occurred on this layer in the past week.
- Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.
- Avoid shallow snowpack areas where triggering is more likely.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 18th, 2020 4:00PM
