Avalanche Forecast

Another day of warm sunny weather then some clouds and light flurries over the weekend.

THURSDAY NIGHT: Partly cloudy, moderate southwest wind, a weak temperature inversion may develop overnight with alpine temperatures in the -2 to 0 C range and cooler in the valleys.

FRIDAY: Mostly sunny with some afternoon clouds, moderate south wind, freezing level around 2000 m with treeline temperatures near 0 C.

SATURDAY: Cloudy with scattered flurries and 5-10 cm of new snow, light southwest wind, freezing level climbs to 1400 m with treeline temperatures near -3 C.

SUNDAY: Cloudy with another 5-10 cm of new snow, light south wind, freezing level around 1300 m with treeline temperatures near -5 C.

Preliminary reports from Thursday suggest warm weather resulted in widespread wet loose avalanches on steep south-facing terrain as well as a few natural wind slab avalanches on south aspects. On Wednesday, in addition to wet loose avalanches, there were a few human triggered slab avalanches showing the impacts of warming on slab avalanche conditions. Two notable incidents were on south-facing slopes in Glacier National Park, including a size 3 wind slab avalanche in a steep alpine couloir (MIN report) and a size 1.5 slab avalanche in below treeline terrain (MIN report). 

Warming is expected to cause heightened avalanche conditions again on Friday. Read more in this Forecaster Blog.

Rising freezing levels and sunshine will be melting, and potentially destabilizing, snow surfaces the next few days. Higher elevations have been impacted by recent wind from the southwest, likely leaving wind slabs lurking on shaded north and east slopes.

The lower snowpack has been strengthening with reactivity on persistent weak layers on the decline. The two layers of concern have been a layer of facets that was buried in mid-February (60-100 cm deep) and a layer of surface hoar and/or crusts that was buried in late January (80-120 cm deep). The current impulse of warming will likely be the final test on these layers, as there is some uncertainty about whether they will become reactive again under these conditions.

• Avoid exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
• If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
• The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.
• Be careful as you transition into wind affected terrain.
• Cornices become weak with daytime heating.