Avalanche Forecast
A widespread avalanche cycle was observed Monday with numerous avalanches up to size 2.5, having occurred today near highway 93N. Freezing levels will peak late tonight, raising the avalanche danger to high at all elevations into Tuesday. Avoid avalanche terrain.
Confidence
Moderate
Avalanche Summary
A widespread cycle was observed on Mt Dennis and Mt Stephen on Monday with slides up to size 2.5. They were a mix of slabs and loose wet avalanches. This cycle is expected to continue into Tuesday with warm temperatures and high freezing levels.
Snowpack Summary
Rain has saturated the snowpack up to 1900 meters and wind has created windslabs in most alpine/treeline areas. These slabs are releasing on two weak layers in the upper snowpack: 1) facets from the cold snap 10-30cm deep, and 2) surface hoar or sun crust below the facets 30-50cm deep. The lower snowpack is comprised of weak facets and depth hoar. Overall this is a weak snowpack that is untrustworthy.
Weather Summary
The next pulse of moisture comes through on Tuesday although not much precipitation is expected, less than 3 cm. Freezing levels fall slightly over all areas to a range of 2100-2400 m. Ridgetop winds remain strong to extreme from the southwest.
Tuesday evening as the winds taper and temperatures cool off, there is the potential for an inversion to set up Wednesday.
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Terrain and Travel Advice
- Avoid areas where the snow feels stiff and/or slabby.
- The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Avalanche Problems
Loose Wet
Rain to 1900 m and warm temperatures have saturated the snowpack below treeline, and this has resulted in widespread wet loose avalanches happening in gullies. The snowpack below treeline will be weak and saturated until temperatures cool days from now.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood: Very Likely
Expected Size: 1 - 2
Persistent Slabs
Recently formed windslabs sit on facets produced during the cold snap, as well as surface hoar/suncrust found below these facets. This is an unstable combination and we've seen evidence of multiple avalanches on this layer over the last week. Avoid steep, open slopes until it cools off again.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 1 - 2.5
Deep Persistent Slabs
The base of the snowpack consists of weak facets, depth hoar, and the overlying crust in the midpack continues to break down. Use caution in steep terrain, large planar slopes, and thin to thick areas where initiating these slabs would be more likely.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1.5 - 2.5