Avalanche Forecast
Issued: Mar 25th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Cornices.
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Avalanche Canada
Expect drastic changes in avalanche conditions as you gain elevation and transition to open wind affected terrain.
Summary
Confidence
Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.
Weather Forecast
THURSDAY NIGHT: Partly cloudy, 30-40 km/h northwest wind, treeline temperatures drop to -10 C.
FRIDAY: Cloudy with some light flurries in the afternoon, 40-50 km/h west wind, treeline temperatures around -6 C.
SATURDAY: Cloudy with scattered flurries and up to 5 cm of snow, 30-50 km/h southwest wind, freezing level climbing to 1500 m, treeline temperatures around -4 C.
SUNDAY: Flurries with 10-20 cm of new snow, 50 km/h south wind, freezing level around 1700 m with treeline temperatures around -2 C.
Avalanche Summary
Heavy snowfall on Wednesday likely resulted in natural avalanche activity. Field observations are limited, but the North Rockies field team observed one natural size 2 storm slab avalanche at Sugarbowl in below treeline terrain on Wednesday (MIN report). Skiers near Blue River also ski cut some size 1 storm slabs.
Storm slabs have stabilized since Wednesday, but are still possible to trigger at upper elevations.
Snowpack Summary
Upper elevations have 15-35 cm of settling storm snow, while below 1500 m the surface is moist or crusty. Steady west wind has likely formed thick wind slabs in lee terrain features. Slightly beneath this new snow is a widespread crust layer from the mid-March warmup. While we don't have recent observations of this layer, we suspect the snow has bonded to this interface.
It appears persistent weak layers have gone inactive over the past week. We had been concerned about a weak facet layer from the mid-February cold snap that is now roughly 150 cm deep. This layer resulted in a few large cornice triggered avalanches in the first half of March, but recent weather patterns have helped this layer heal.
Terrain and Travel
- Be alert to conditions that change with aspect and elevation.
- Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
- Avoid freshly wind loaded terrain features.
- Caution around convexities or sharp changes in terrain.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Storm Slabs
Human triggered slabs are possible at upper elevations where there is 15-35 cm of storm snow. Pay attention to changes in new snow depth as you gain elevation, and be extra cautions on wind loaded slopes.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Where cornices exist they pose a threat both from the potential for them to collapse under your feet (or machine) and from the potential to send large chunks of snow far down a slope.
Aspects: North, North East, East, South East.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Mar 26th, 2021 4:00PM
