Avalanche Forecast

Issued: Feb 1st, 2016 4:36PM

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

Ruari Macfarlane, Parks Canada

Waterton Lakes.

Wind Slabs are hidden by a few cm of new snow, while deeper in the snowpack, a "Low probability / High consequence" problem lurks. If we see more snow or higher temperatures than forecast, hazard could rise to Considerable at Alpine & Treeline.

Summary

Weather Forecast

A few cm of snow forecast in flurries Tuesday and Thursday, while Wednesday is looking mainly clear and dry. Winds are forecast at Light from the West, with cool and steady temperatures, until Wednesday; when an increase to strong SW wind heralds a modest warming trend. Freezing Levels should reach the townsite by late Wednesday / Thursday.

Snowpack Summary

Upto 20cm of snow fell in the alpine on Thursday/Friday, being redistributed into Wind Slabs in the Alpine and Treeline. From Treeline down, rain formed a new crust, making for Variable ski conditions lower down. A December crust buried around a meter deep, although generally requiring large triggers, has potential to produce large avalanches.

Avalanche Summary

A small loose dry avalanche was observed in steep treeline terrain on Monday above Forum Lake. Several slab avalanches were observed on Friday near Forum and Cameron Lakes. These were small, with the exception of a Large (Size 3) slab avalanche, from a NE aspect on Forum Peak. This propagated surprisingly wide (300m) and ran onto Cameron Lake.

Confidence

Intensity of incoming weather systems is uncertain on Wednesday

Problems

Wind Slabs

Buried wind slabs exist lee to previous SW winds. While stubborn, these wind slabs may propagate surprisingly far where they are hard, or sit on a hard surface. From Wednesday afternoon onwards, watch for for development of small new Wind Slabs.

Be cautious as you transition into wind affected terrain.Be aware of the potential for wide propagations due to the presence of hard windslabs.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

Facets atop a deeply buried crust produced large avalanches in neighboring areas lately, and are giving Sudden results in tests. The strength of this layer is highly variable across terrain, so a conservative approach to wide-open terrain is crucial.

Carefully evaluate big terrain features by digging and testing on adjacent, safe slopes.Be aware of the potential for large, deep avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

1 - 3

Valid until: Feb 4th, 2016 4:00PM