Avalanche Forecast

An intense Pacific front plows through on Saturday and hammers the region with snow and wind

Friday night: Cloudy, 5-15 cm of snow, strong southwest wind, treeline temperatures rising to -4 C overnight, freezing level rising to 1200 m.

Saturday: Cloudy, 5-15 cm of snow, strong southwest wind, treeline temperatures dropping to -8 C, freezing level dropping to valley bottom by end of day.

Sunday: Mainly cloudy, up to 5 cm of snow, moderate southwest wind, treeline temperatures near -10 C, freezing level around 500 m. 

Monday: Mix of sun and cloud, isolated flurries with up to 5 cm of snow, light winds becoming east, treeline temperatures near -8 C, freezing level around 500 m.

 We expect that natural and human triggered avalanches will release large and run far during the storm. 

A potent storm with strong wind is forecast to bring 15-30 cm of new snow to the mountains by the end of Saturday, favoring areas south in the region near Allison Pass. This will create a widespread, reactive storm slab problem that will be particularly pronounced where the snow is drifted by southwest winds. The snowpack will need time to adjust to this rapid load. Closely monitor how the new snow is bonding to the old surface as the cold snow is not expected to bond well to previous snow surfaces.

In the north of the region, the snowpack near upper treeline elevations is complex and warrants conservative route selection. Weak faceted snow can be found near two possible crust layers that formed in early December, which may become reactive with loading from new snow. Our models suggest that this layer may be most pronounced at elevations between 1400-1800 and in areas north in the region, like the Hurley.  

The south of the region has seen substantially higher snow totals over the past week, with some areas seeing 50+ cm. Expect to find deeper snow accumulations above the December crust and anticipate larger, more reactive storm slab avalanches.

Having endured warmer temperatures and more rainfall, the southern part of the region is just reaching the threshold for avalanches at most elevations. 

• Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
• Expect slab conditions to change drastically as you move into wind exposed terrain.
• Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
• Be aware of the potential for large avalanches due to the presence of a persistent slab.