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 Loose Wet, Cornices and Wind Slabs.
swerner,
Avalanche Canada
The heat is on!
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 +6 degrees and freezing levels 2100 m.
Thursday: Cloudy with light precipitation. Ridgetop wind strong from the southwest. Alpine temperatures +5 and freezing levels 1900 m.
Friday: Cloudy. Ridgetop wind light from the southwest. Alpine temperatures 1 and freezing levels 1000 m.
Avalanche Summary
Freezing levels are expected to rise to the mountain top on Wednesday. Warm temperatures and periods of sunshine will likely destabilize the snowpack and initiate natural avalanches. Pockets of wind slab may continue to be reactive to human triggering at upper elevations.
Cornices are large and could also deteriorate under the warm spring sun. They require a large berth from above and below.
On Sunday, a recent MIN report showed the new 10 cm of storm snow was easily running on a firm crust below 1200 m.
Snowpack Summary
A mix of rain and snow brought 30-50 cm/mm of precipitation to the region since the weekend, accompanied by moderate to strong southerly winds. Strong and switching winds (SW to NW) may have formed fresh wind slabs below ridgelines. These wind slabs may be more reactive where they sit above a firm crust. The average snowpack depth at treeline elevations is 350 cm.
A solid melt-freeze crust exists at lower elevations but will likely soften and destabilize during daytime warming.
Along ridgelines, cornices are large and may weaken when the sun comes out.
Terrain and Travel
- Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
- Brief periods of sun could quickly initiate natural avalanche activity.
- Be aware of highly variable recent wind loading patterns.
- Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
- Cornices become weak with daytime heating or solar exposure.
Problems
Loose Wet
The spring sun and rising freezing levels (2000 m) can pack a punch quickly and initiate loose wet avalanches on all aspects. At higher elevations where the recent storm snow deposits are deeper, loose wet avalanches may be able to entrain more snow or initiate larger wet slabs.
Watch for signs of instability like natural avalanche activity, wet or moist snow surfaces, and snowballing, especially on solar aspects.
Aspects: All aspects.
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. They become increasingly weak when the sun comes out and freezing levels rise. They require a large berth when travelling above and below them.
Aspects: North, North East, East, West, North West.
Elevations: Alpine.
Likelihood
Expected Size
Wind Slabs
30-40 cm of fresh snow has recently fallen at upper elevations. Strong and changing ridgetop winds from the southwest to the northwest may have formed wind slabs on many aspects. Wind slabs may be reactive to human triggering on Wednesday.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 31st, 2021 4:00PM
