Avalanche Forecast

Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system.

A major storm system is expected to continue to impact the region until Monday night and may end up lingering into Tuesday morning. Forecast snowfall amounts are quite uncertain and may have substantial variability across the region. 

Sunday Night: Snowfall 20-40 cm, strong to extreme SW wind, freezing level low around 1000 m/high around 1300 m. 

Monday: Snowfall 15-30 cm, strong SW wind, freezing level high around 1100 m. 

Tuesday: A mix of sun and cloud with lingering flurries in the morning, moderate W wind easing through the day, freezing level high around 1300 m.

Wednesday: Mainly sunny, light variable wind, freezing level high around 1600 m.

An early report from Sunday includes several small skier triggered storm slabs which were sliding on a melt-freeze crust. One of these was remotely triggered from 10 m away suggesting a weak bond between the storm snow and the underlying crust. 

On Saturday, explosive triggered a few cornices including a size 2 cornice which triggered a size 1 storm slab on the slope below. Ski cutting was triggering size 1 soft slabs with 5-15 cm of recent storm snow sliding on the firm melt-freeze crust. A skier also triggered a size 1 wind slab on a north aspect at 2100 m elevation which was 15 cm thick. This MIN report describes a small skier triggered wind slab which slid on a hard crust and a small natural avalanche which was solar triggered. 

On Friday, explosives triggered a couple size 1-2 cornices. One of these cornices triggered a slab avalanche on a northwest aspect in the alpine which likely failed on the mid-March interface down 50 cm.

As of Sunday afternoon, weather stations were showing 20-30 cm of new storm snow accumulation. This storm snow has buried a strong, supportive crust which extends to mountain top on solar aspects and to around 2200 m on northerly aspects. Strong southwest wind will be redistributing the new storm snow in exposed high elevation terrain forming touchy wind slabs and developing large cornices. The new storm snow was reported to be moist below 1300 m on Sunday. 

Below the crust, the upper snowpack consists of a number of crust/facet/surface hoar interfaces buried in March that seem to have bonded well during the recent warm weather. 

The middle and lower snowpack are generally strong and well bonded. 

• Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
• Make conservative terrain choices and avoid overhead hazard.
• Pay attention to cornices and give them a wide berth when traveling on or below ridges.
• The more the snow feels like a slurpy, the more likely loose wet avalanches will become.