Avalanche Forecast
Regions: Dogtooth, East Purcell, Purcells.
Dangerous avalanche conditions exist where increasing winds are building fresh wind slabs over weak layers.
Deep instabilities are best managed through conservative terrain selection.
Confidence
Moderate
Avalanche Summary
On Sunday, explosives control produced a few, size 3, deep persistent slab avalanches on reloaded bed surfaces. Wind slab avalanches, to size 2, were reported to be reactive to natural and human triggers in the region.
If you go out in the backcountry, please consider sharing your observations on the Mountain Information Network (MIN).
Snowpack Summary
Cold temperatures are slowly faceting the upper snowpack. Variable winds have redistributed 40 cm of low-density snow into wind slabs in exposed lees at higher elevations.
The mid and lower snowpack is generally weak with several layers of note. Of greatest concern are weak facets and/or depth hoar located at the bottom of the snowpack, particularly in alpine terrain.
Snowpack depths at treeline range from 60 to 150 cm.
Weather Summary
Monday Night
Partly cloudy with no precipitation, northwest alpine wind 10 to 30 km/h, temperature inversion present with treeline temperature around -15 °C and valley bottom temperatures around -25 °C.
Tuesday
Mainly cloudy with isolated flurries, trace amounts of snow, westerly alpine wind 20 to 40 km/h, treeline temperature -14 °C.
Wednesday
Cloudy with scattered flurries, 6 to 12 cm of snow, southwest alpine wind 10 to 25 km/h, treeline temperature -18 °C.
Thursday
A mix of sun and cloud with no new precipitation, variable alpine wind 10 to 25 km/h, treeline temperature -20 °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.
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Avalanche Problems
Wind Slabs
Increasing westerly winds will redistribute available snow into fresh wind slabs at higher elevations. Avoid lee terrain features where wind slabs may be reactive to human triggering.
Aspects: North, North East, East, South East, South, South West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 2
Deep Persistent Slabs
The lower snowpack is characterized by facets and depth hoar near the base of the snowpack in most alpine areas. The likelihood of triggering a deep persistent slab is low, however the consequence of doing so is high.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Unlikely - Possible
Expected Size: 1.5 - 3