Avalanche Forecast

A ridge of high pressure builds on Saturday bringing dry and sunny conditions with mild temperatures. 

Friday Night: Snowfall up to 5 cm, moderate to strong SW wind, treeline temperature around -6 °C. 

Saturday: A mix of sun and cloud, moderate W-NW wind, freezing level reaching as high as 1500 m. 

Sunday: Mainly sunny, moderate W wind, freezing level reaching as high as 2000 m. 

Monday: A mix of sun and cloud, moderate to strong W wind, freezing level as high as 2000 m. 

On Thursday, three natural size 1-1.5 wind slabs were reported on east through south aspects at 2200 m elevation and explosives triggered one size 1 wind slab. Loose dry activity up to size 1.5 has been reported over the last few days. 

Earlier in the week, shooting cracks and whumpfing had been reported which indicates the buried surface hoar layer is very weak. So far, this layer has primarily produced avalanches in wind loaded terrain but if warming causes a slab to form, a more widespread persistent slab problem should be expected. The surface hoar distribution is spotty and not found at some locations in the region. 

Prior to Friday's storm, 20-40 cm of snow from last Sunday buried the January 30 interface which consists of a melt freeze crust on all aspects to around 2000 m and on solar aspects extending well into the alpine, spotty surface hoar in sheltered areas at and below treeline which may be large in some places, and/or small facets. Prior to Friday's storm, the older storm snow had not formed a slab in most places except for where it was wind loaded. With warming and sun this weekend, rapid settlement is possible and this may result in the formation of a more widespread reactive slab over the potentially weak surface hoar/crust/facet interface. Ongoing wind over the past week has formed reactive wind slabs in exposed terrain at higher elevations and new wind slabs may build during Friday's storm.

The early December crust/facet persistent weak layer is now 100-200 cm deep. This layer produced numerous very large avalanches in January but is now considered dormant. We continue to track this layer of concern and expect it will wake up again with sustained warming or a large storm event. This recent forecaster blog goes into more details on the layer.

• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
• Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
• The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.