Solar radiation has an effect on the snowpack mid day through mid afternoon on steep sun affected slopes. Even though proper spring is yet to arrive, significant diurnal swings of up to 20 °C between the morning and afternoon are stressing the already weak snowpack.Ice climbers should be especially careful in sun exposed low elevation gullies as even a small slide could have serious consequences.
Thin to thick areas are most suspect spots to trigger the deeper instabilities.
Previous moderate to strong winds from the SW have formed wind slabs in some open tree line and in the alpine.While assessing recent wind affect, keep in mind the potential of triggering either older wind slabs below or deep instabilities at the bottom of the snowpack, especially in thin to thick zones.
The bottom of the snow pack is inherently weak with well developed Facets and Depth Hoar. Although natural avalanche activity has slowed down and snowpack test results are less conclusive on this layer; skier triggering is still possible.
Avalanche control on Hwy 93N with the use of large explosives resulted in few wind slab and numerous loose dry avalanches up to size 2 on Wednesday.
Natural activity has tapered off but the snowpack has proven sensitive to small inputs of new snow, loading, temperature change, and potentially solar effect. Careful evaluation of these inputs is essential.
Don't forget to post avalanche observations to the MIN.
In sheltered areas the top 20 to 40cm is comprised of low density facetted crystals. There is extensive wind effect at tree line and above from previous SW winds. Sun crust is forming on steep solar slopes at tree line and below.
This is sitting on top of a generally weak mid and lower snowpack. Facets and depth hoar linger at the base of the snowpack with the height of snow varying from 60 to 160cm.
The surface ridge of high pressure will remain in place until Friday. Clear skies, variable light wind, and temperatures slightly below seasonal are expected. Freezing level forecast to remain at or near valley bottom. An upper low may bring some flurries Friday and Saturday.
Detailed weather forecasts from Avalanche Canada: https://avalanche.ca/weather/forecast
