Avalanche Forecast

Issued: Mar 29th, 2017 4:22PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs and Cornices.

mbender, Avalanche Canada

Sea To Sky.

Forecast warm temperatures and potential extended sunny periods on Thursday and Friday will keep the avalanche danger elevated

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain on Thursday

Weather Forecast

THURSDAY: Cloudy with sunny periods / Light to moderate northwest wind / Alpine temperature -3 / Freezing level 1500mFRIDAY: Cloudy with sunny periods / Moderate southwest wind / Alpine temperature -2 / Freezing level 1300mSATURDAY: Flurries / Light southwest wind / Alpine temperature -2 / Freezing level 1300m

Avalanche Summary

A report from Tuesday indicated a natural size 2 cornice failure that was suspected to be triggered by warming temperatures at tree line on a west aspect. Additionally, on Tuesday and Wednesday several explosive and skier controlled avalanches to size 2 and 2.5 were reported from a variety of aspects. These were mostly wind and storm slabs failing 10-40cm deep. Some were also triggered by cornices pulling out 20-40cm slabs on slopes below.

Snowpack Summary

Continued light to moderate snowfall over the past few days has accumulated 30-60cm of storm snow that has been redistributed by predominantly southwest and southeast winds. 2000m and below, the storm snow lies above a crust that formed last week. A rain crust that was buried mid March is now 90-120 cm deep. The mid-February crust/facet layer can still be found at the upper end of tree line and into the alpine. This interface is generally 120-170 cm deep but may be present nearer to the surface in wind scoured areas. Although there is growing confidence that this layer is becoming dormant, a storm slab or cornice release in the right location may have the potential to trigger any of the deeply buried weak layers.

Problems

Storm Slabs

New storm slabs are expected to continue to be reactive as the sun comes out on Thursday. The new snow could present as loose wet avalanches at lower elevations or on steep sun exposed slopes at upper elevations.

The new snow will require several days to settle and stabilize.Be cautious as you transition into wind affected terrain.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

Cornices

With recent warm temperatures, snow and wind cornices have grown large and overhanging. While cornices are a hazard in themselves, the danger increases when they have the potential to act as a trigger to slabs sitting beneath them.

Even small cornice falls may trigger larger avalanches.Avoid exposure to slopes that have cornices overheadGive cornices a wide berth when traveling on ridges. Use

Aspects: North, North East, East, South East, South.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Mar 30th, 2017 2:00PM