Glacier National Park Avalanche Forecast

Issued: Dec 28th, 2020 8:04AM

Sun Dec 27th Current Conditions
Alpine Moderate Treeline Moderate Below Treeline Low
Mon Dec 28th 2 Day Outlook
Alpine Moderate Treeline Moderate Below Treeline Low
Tue Dec 29th 3 Day Outlook
Alpine Considerable Treeline Moderate Below Treeline Moderate

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Loose Dry and Persistent Slabs.

Assess your line before committing.

We currently have a complex snowpack with persistent weak layers that could produce high consequence avalanches if you were unlucky enough to trigger them.


Weather Forecast

A ridge of high pressure will give stable weather through Tuesday. A system arriving from the West will give light snowfall Wednesday.

Today: Cloudy with sunny periods and isolated flurries. Alpine High -9 C. Ridge wind light W.

Tonight: Clear periods. Alpine Low -13 C. Light W wind.

Tuesday: Sunny periods. High -8 C. Light SW wind.

Snowpack Summary

Up to 25cm of recent snowfall has buried windslabs at upper elevations, and spotty surface hoar in sheltered areas below treeline. The upper snowpack is generally well bonded. Weak layers: Dec 13 surface hoar is down 70-110cm, Dec 7 crust/facte/surface hoar layer is down 110-130cm+. The Nov 5 crust lingers near the base of the snowpack.

Avalanche Summary

Small natural and skier triggered loose dry avalanches occurred over the weekend on steeper, open slopes on all aspects and elevations.



Loose Dry

An icon showing Loose Dry


Likely - Possible

Expected Size

1 - 2

Slough management is necessary on steeper, open slopes. Initiated loose dry slides are gathering enough mass to push a skier or rider over, or even bury one in a terrain trap. Manage your group carefully to enjoy the new snow!

  • Be careful of loose dry power sluffing in steep terrain.
  • If triggered dry loose point releases can form deeper deposits in terrain traps.


All aspects.


All elevations.

Persistent Slabs

An icon showing Persistent Slabs


Possible - Unlikely

Expected Size

2 - 3.5

The Dec 7th and Dec 13t layers produced very large avalanches last week, up to size 4! One of these very large avalanches, from a South aspect at Treeline, had the Dec 7th interface as the failure plane which consisted of a crust with facets above.

  • Carefully evaluate terrain features by digging and testing on adjacent, safe slopes.
  • Be aware of the potential for wide propagations which could result in large avalanches.


All aspects.


All elevations.

Valid until: Dec 29th, 2020 8:00AM