Avalanche Forecast
Regions: Brazeau, Churchill, Cirrus-Wilson, Fryatt, Icefields, Jasper, Maligne, Marmot, Miette Lake, Pyramid.
Continued uncertainty regarding forecasted precipitation amounts. Convective flurries could produce up to 20cm overnight Tuesday into Wednesday. Moderate southwest winds on Tuesday have added to the new wind slab which has shown the ability for wide propagation in the alpine.
Rolling closures planned for Maligne Lake Road south of Medicine Lake 1500-1700hrs for avalanche control.
Confidence
Moderate
Avalanche Summary
Explosive control Sunday on a large road side cut bank at 1800m produced several wet loose avalanches up to size 2.5 - isothermal running on the basal facets.
Patrol on 93 Monday and Tuesday observed 3 size 2 wind slabs variable aspects in the alpine showing descent propagation and one size 2.5 off Saskatchewan that reached the run out - limited visibility on Tuesday.
Don't forget to post avalanche observations to the MIN.
Snowpack Summary
Up to 20cm (14mm) precipitation since Sunday sits atop our April 9 melt freeze/solar crust. Snow in the alpine was accompanied by strong southwest winds creating new wind slab lee and cross loaded features. Snowpack below 1800m is in a diurnal isothermal freeze thaw. The mid pack above this elevation consists of multiple layers of dense wind effected snow in open areas, sun crusts on solar aspects, and facets. Depth hoar and basal facets make up the base of the snowpack.
Weather Summary
Continued unsettled conditions are expected Wednesday. Models once again vary showing trace to 15cm possible. Winds will be moderate to strong SW overnight falling to light values by Wednesday morning. Freezing level 1500m Wednesday and Thursday; valley bottom overnight. Clearing trend Thursday.
Terrain and Travel Advice
- Minimize exposure during periods of heavy loading from new snow, wind or rain.
- If triggered loose wet avalanches may step down to deeper layers resulting in larger avalanches.
Avalanche Problems
Wind Slabs
Additional precipitation with strong SW winds will rapidly build new and add to our wind slab problem on lee and cross-loaded features. New snow could settle into storm slabs on southerly aspects depending on localized snowfall amounts and winds.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2.5
Loose Wet
Stronger overnight freezes may keep this problem in check until mid to late afternoons. Wet loose avalanches will likely step-down to our basal facets in steep terrain resulting in large avalanches
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2.5
Deep Persistent Slabs
The bottom of the snowpack is inherently weak with well-developed Facets and Depth Hoar. Storm /Wind slabs or wet loose avalanches could trigger the deep persistent slab resulting in large avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 2 - 3.5