Avalanche Forecast
Regions: Bull, Elkford East, Elkford West, Flathead, Lizard, Lizard-Flathead, South Rockies.
Watch for wind loaded features as you move through terrain. Strong winds and snow are expected Saturday afternoon.
A buried surface hoar layer may increase reactivity, and small avalanches may step down to deeper weak layers.
Confidence
Moderate
Avalanche Summary
On Thursday loose dry avalanches to size 2 were reported in steep terrain features.
On Tuesday explosive control produced a few small avalanches, up to size one.
A natural size 2.5 persistent slab avalanche was reported, thought to have occurred on Tuesday. This avalanche occurred on a northeast aspect, 2000 m on a reloaded bed surface.
Snowpack Summary
New snow accumulates over the day, redistributed into larger deposits in east and north facing terrain. Slabs form over facets, surface hoar or a crust and may not bond well.
Around 50cm deep a layer of surface hoar at treeline and a thin crust on steep south facing slopes exists. This layer was formed in early December and is less widespread than the other layers of concern in the snowpack.
The mid-November layer consisting of facets and surface hoar is now buried around 80 cm deep.
The snowpack in the forecast region is quite variable and increasingly complex with snowpack depths at treeline varying from 100cm to 200cm.
Weather Summary
Friday Night
Cloudy with 5 cm of snow expected. Moderate westerly winds. Freezing levels below valley bottom.
Saturday
Mostly cloudy with around up to 15cm of new snow expected late afternoon. Strong to extreme southwest winds and a high of -16°C
Sunday
5-10 cm possible overnight. Mostly cloudy with light flurries bringing trace amounts of new snow. Moderate westerly winds. Freezing levels around 500 m, high temperatures of -10°C.
Monday
Cloudy with 5 cm of snow expected. Strong southwest winds return. Freezing levels rise, to around 1000 m with an above freezing layer possible at 2000 m. High temperatures of 0°C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Avalanche Problems
Wind Slabs
Fresh snow and strong winds will develop new and reactive slabs at treeline and alpine elevations into deeper and more reactive wind slabs.
Expect slabs to be reactive as they sit over a variety of weak surfaces - facets, a crust and/or surface hoar. Where strong winds are observed slabs could be found further down slope than expected.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 2
Persistent Slabs
Two concerning persistent weak layers can be found in the top meter of the snowpack. The first is a surface hoar/crust layer from early December and the second is a surface hoar, facet or crust layer from mid November. These layers are most concerning on sheltered treeline features where surface hoar is most likely to be preserved.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Unlikely - Possible
Expected Size: 1.5 - 3