Spring Conditions. The ridge of HIGH pressure is breaking down and a weak storm is moving on-shore from the south. High daytime freezing levels will continue the cycle of wet slab and loose wet avalanches.
Summary
Weather Forecast
Clear overnight with freezing levels near 2000 metres and moderate southerly winds. High cloud developing Thursday morning with freezing levels rising up to about 3000 metres. Winds becoming easterly in the afternoon as the cloud increases and light precipitation begins to fall. Freezing levels dropping to 2000 metres by Friday morning with light precipitation and light easterly winds. Freezing levels dropping to 1500 metres on Saturday with 5-15 cm of new snow expected in the alpine.
Avalanche Summary
Some thin wind slab avalanches were released by explosives in the north of the region near Stewart. I suspect that recent wind slabs have settled out and either released naturally in the sun or have melted and re-frozen into the spring snowpack. There are not may commercial operations still working in the field, so data is sparse at this time of year. If you have observations from your travels, please consider sharing through the MIN (Mountain Information Network).
Snowpack Summary
Overnight cooling has formed a new surface crust on all aspects above 1000 metres. Daytime heating continues to melt the surface snow on all aspects. Recent wind slabs are suspected to have settled out due to the high temperatures and strong solar. There is about 40 cm of moist snow above the early April melt freeze crust in the Stewart area. This buried crust may act as a sliding layer for wet slab avalanches. Large wet slab avalanches may step down to the ground or gouge down to the ground in their tracks. Cornice falls and loose wet avalanches are likely during periods of strong solar radiation and high daytime freezing levels. Travel early before crusts break down, and monitor crust thickness and strength throughout the day.
Problems
Wet Slabs
Wets slab avalanches continue to be a concern due to strong solar radiation and high daytime freezing levels. Forecast cloud may decrease the likelihood once the freezing levels drop and new surface crusts form.
Be aware of the potential for large, deep avalanches.>Plan to be off big slopes before the temperatures rises and the snowpack deteriorates.>
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Loose Wet
Loose wet avalanches may continue due to one more day of high daytime freezing levels. If it rains before the surface re-freezes, loose wet avalanches will be very likely.
Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Look for signs of surface instabilities such as pinwheeling and point releasing near cliffs.>
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 21st, 2016 2:00PM
