Avalanche Forecast

Sunday ushers in Dr. Jekyll's benign weather following Mr. Hyde's Saturday storm

Saturday night: Cloudy, scattered flurries with trace accumulations above 700 m, moderate west winds decreasing to light, treeline temperatures cooling from -1 C to -3 C, freezing level dropping to 500 m.

Sunday: Partly cloudy, isolated flurries with trace accumulations, winds becoming east and light, high treeline temperatures near -3 C, freezing level around 700 m.

Monday: Mainly sunny, no precipitation expected, light north winds, high treeline temperatures near-1 C, freezing level around 300 m.

Tuesday: Increasing cloudiness, no precipitation expected, winds becoming southwest and increasing to moderate, high treeline temperatures near 0 C with an above freezing layer between 1000-1500 m. 

On Saturday, operators reported several small (size 1-1.5) human and explosive-trigged avalanches on north and west aspects at treeline elevations. It may remain possible to human-trigger avalanches in the recent snow on Sunday.

Since Friday, the mountains have picked up 20-50 cm of new snow, favoring areas in the southwest of the region. Gradual warming that peaked midday likely created a thin crust within the storm snow in areas below 1300 m. A rise in temperature and strong southwest winds likely accelerated slab formation. If you are increasing your exposure to avalanche terrain, do it gradually as you gather information. Stay alert to changing slab conditions as you move into wind-exposed terrain, and closely monitor the bond of the new snow to the old snow surface. 

Below up to a meter of snow from the past week, two crust layers can be found that formed in early December. Small facets (sugary snow) have been reported near these crusts that may transition into a persistent slab problem. Recent snowpack tests have demonstrated instability at this interface, though with limited propagation potential. This layer could have potential to be triggered in shallow, rocky zones near ridge tops, where the facets are more developed and where the crust layers are more accessible to the weight of a person or machine. Check out this MIN report from the Elk Mountain area on Tuesday. 

Below these crust layers, the snowpack is generally well-settled. Early season hazards such as rocks, stumps, and open creeks remain at lower elevations.

• Continue to make conservative terrain choices while the storm snow settles and stabilizes.
• Closely monitor how the new snow is bonding to the old surface.
• Expect slab conditions to change drastically as you move into wind exposed terrain.
• Seek out sheltered terrain where new snow hasn't been wind-affected.
• If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.