Avalanche Forecast
Issued: Mar 30th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Loose Wet and Cornices.
swerner,
Avalanche Canada
Wind slabs could be reactive to skier and rider triggering.
Rising freezing levels and pockets of sunshine can pack a punch and quickly initiate natural avalanches. Back off slopes before the snow turns moist and avoid overhead hazards like cornices and large avalanche paths.
Summary
Confidence
Weather Forecast
A ridge of high pressure will keep the region mostly dry on Wednesday. A frontal wave will bring cloudy skies and light snow amounts by Thursday.
Wednesday: Mix of sun and cloud. Ridgetop wind moderate from the southwest. Alpine temperatures near 0 degrees and freezing levels 1600 m.
Thursday: Cloudy with light snow 2-5 cm. Ridgetop wind strong from the southwest and freezing levels 1200 m.
Friday: Cloudy with snow amounts 5-10 cm. Ridgetop wind light from the southwest. Alpine temperatures -6 and freezing levels 1000 m.
Avalanche Summary
By midday on Tuesday reports indicated that small loose wet avalanches occurred from steep rocky terrain. Cornices also became weak and failed with daytime warming. No slabs were reported from the slopes below.
On Sunday, natural storm slab avalanches up to size 2 were reported and numerous size 1.5 slabs were easily triggered by skiers and riders from steep slopes where the new snow sits above a crust.
The likelihood of triggering avalanches will decrease somewhat in the wake of Sunday's storm, however, human triggering remains likely, especially in wind loaded areas at upper elevations. With so much new snow, even short periods of direct sun can trigger natural avalanches. Cornices are large and should be given a wide berth, especially when the sun comes out.
Snowpack Summary
Up to 40 cm of snow fell throughout the region since the weekend. This was accompanied by strong southwest winds that switched to the northwest. Reactive wind slabs could be lingering on a variety of aspects at upper elevation, especially where they sit above a crust.
The recent snow sits above a widespread melt-freeze crust, with the exception of high north-facing terrain. It may also be sitting on small surface hoar crystals reported on north and east aspects in the alpine. This recent precipitation likely fell as rain in many areas below treeline. A melt-freeze crust exists below treeline.
Cornices along ridgelines are large, and the likelihood of them failing will increase when the sun comes out.
Terrain and Travel
- Brief periods of sun could quickly initiate natural avalanche activity.
- Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
- Be aware of highly variable recent wind loading patterns.
- Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
Problems
Wind Slabs
Changing wind from southwest to northwest has added complexity to the snow loading pattern. You may find reactive wind slabs on unsuspecting slopes and on a variety of aspects, especially where the slab sits above a crust.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
The spring sun combined with rising freezing levels can pack a punch quickly and initiate loose wet avalanches. Watch for signs of instability like natural avalanche activity, wet or moist snow surfaces, and snowballing, especially on solar aspects.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Cornices are large and looming along many ridgelines, and have likely grown with the recent snow and wind. Direct sun and rising freezing levels can weaken cornices significantly.
Aspects: North, North East, East, West, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Mar 31st, 2021 4:00PM
