Avalanche Forecast
Issued: Mar 31st, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Cornices.
swerner,
Avalanche Canada
Changing wind has sifted the recent storm snow onto a variety of aspects at upper elevations. Wind slabs may be reactive to skier and rider triggering. Signs of wind slab instability include stiff snow and shooting cracks while you travel, whumphing and hollow sounds.
Summary
Confidence
Weather Forecast
A frontal wave will bring unsettled conditions including cloudy skies and light snow amounts.
Wednesday Night: Cloudy with alpine temperatures near -3. Ridgetop wind strong from the southwest and freezing levels 800 m.
Thursday: Cloudy with flurries. Ridgetop wind light from the southwest. Alpine temperatures near -4 and freezing levels 1200 m.
Friday: Cloudy with flurries. Ridgetop wind light from the southwest. Alpine temperatures -7 and freezing levels 1000 m.
Saturday: Snow amounts 10-20 cm with moderate ridgetop wind from the southwest. Freezing level 1200 m.
Avalanche Summary
No new avalanche reports by Wednesday afternoon.
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.
Wind slabs may be reactive to human triggering on wind-loaded slopes at upper elevations. Cornices are fragile and pose a threat from above and below.
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 elevations, especially where they sit above a crust.
The recent snow sits above a variety of old snow surfaces comprising mostly of a widespread melt-freeze crust with the exception of high north-facing terrain where it may be sitting on small surface hoar crystals. A melt-freeze crust exists at treeline and an isothermal trend exists below 1100 m.
Cornices along ridgelines are large, and the likelihood of them failing will increase when the sun comes out.
Terrain and Travel
- Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
- Be aware of highly variable recent wind loading patterns.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
- Seek out sheltered terrain where new snow hasn't been wind-affected.
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 or feathery surface hoar crystals that were possibly buried on high northerly, wind-sheltered slopes. .
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Cornices are large and looming along many ridgelines, and have likely grown with the recent snow and wind. They require respect and a large berth if you're travelling above or below.
Aspects: North, North East, East, West, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Apr 1st, 2021 4:00PM
