Avalanche Forecast
Issued: Mar 28th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Cornices.
ahanna,
Avalanche Canada
Overnight snow and moderate wind shifting northwest will continue to build touchy slabs and elevate avalanche hazard at upper elevations. Crusty surfaces below treeline will make for low hazard but difficult travel conditions.
Summary
Confidence
Moderate - Forecast snowfall amounts are uncertain. Uncertainty is due to how quickly the snowpack will recover and gain strength.
Weather Forecast
Convective instability behind the storm will bring additional snowfall to some areas overnight Sunday and into Monday. Specific locations and amounts are notoriously difficult to forecast for this type of weather pattern.
Sunday night: 5-15 cm new snow. Moderate to strong northwest wind. Freezing level drops to valley bottom. Alpine temperature -11.
Monday: Flurries bringing a trace of new snow. Moderate northwest wind. Freezing level 800 m. Alpine temperature -12.
Tuesday: Mostly cloudy. Light westerly wind. Freezing level 1500 m. Alpine temperature -5.
Wednesday: Sunny. Light southwest wind. Freezing level 2100 m. Alpine temperature -1.
Avalanche Summary
We are still awaiting reports of avalanche activity from the weekend's storm. A widespread natural cycle is likely to have occurred Sunday.
There have been a few notable slab avalanches over the past week. On Saturday, several natural cornice falls triggered size 2-3 avalanches. One of which is suspected to have run on a deeply buried crust near the base of the snowpack. On Thursday a natural size 3 was observed on a east aspect at 1800 m in the Valhallas. The crown was 100 cm thick, but no other details are known. On Wednesday there was a size 2 skier triggered avalanche on a east facing slope at 2250 m in the southern Selkirks, running on a 30 cm deep crust layer.
Snowpack Summary
The weekend's storm dropped 20-40 cm over the Selkirk mountains and 5-10 cm in the Monashees. This snow has likely been redistributed by strong wind, switching from southwest to northwest Sunday night. Crusty surfaces exist below treeline.
At alpine and treeline elevations, a few layers of note are buried 40-80 cm deep including a layer of small surface hoar crystals on shady, wind-sheltered aspects and a series of crusts on solar aspects and below 1800 m. Overall the snow seems to be bonding well to these interfaces, although there have been a few isolated avalanches running on crusts layer over the past few days.
Terrain and Travel
- Be careful to keep storm day fever from luring you out into bigger terrain features.
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Seek out sheltered terrain where new snow hasn't been wind-affected.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Problems
Storm Slabs
Human triggered storm slab avalanches are likely on Monday. Storm slabs will likely be most sensitive to triggering in wind loaded terrain features. Wind direction has varied from southwest to northwest so watch for these deep, reactive pockets on a variety of aspects.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Cornices are likely fragile due to rapid growth with recent snow and wind.
Aspects: North, North East, East, South East.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Mar 29th, 2021 4:00PM
