Avalanche Forecast

Issued: Feb 19th, 2017 4:43PM

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.

shorton, Avalanche Canada

South Rockies.

Watch for isolated wind slabs and shallow snowpack areas where triggering a deep persistent slab avalanche remains possible.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

MONDAY: Cloudy with isolated flurries, moderate southwest winds, freezing level around 1500 m.TUESDAY: Flurries with 5-10 cm of new snow, strong southwest winds, freezing level around 1500 m.WEDNESDAY: Cloudy, light southwest winds, cooling trend with alpine temperatures around -10 C.

Avalanche Summary

On Sunday, a few size 1-1.5 naturally triggered storm slabs and loose dry avalanches were reported on north and east treeline aspects.On Monday, watch for fresh wind slabs at higher elevations. Also keep in mind that the deep persistent slab problem is a low probability/high consequence scenario that warrants extra caution around large open slopes, especially in shallow snowpack areas.

Snowpack Summary

Light flurries will add to 5-10 cm of recent snow with moderate to strong southwest winds forming deeper deposits and wind slabs. The new snow sits above a thick rain crust below 1900 m. A stiff midpack sits above weak sugary snow near the ground. This deep persistent weakness is primarily a concern in shallow snowpack areas. Watch this video from the South Rockies field team for some recent test results on this layer.

Problems

Wind Slabs

Watch for fresh wind slabs in exposed high elevation terrain.

Be alert to conditions that change with elevation.Use ridges or ribs to avoid pockets of wind loaded snow.Use caution above cliffs where small avalanches may have severe consequences.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Deep Persistent Slabs

A weak layer near the base of the snowpack has the potential for large avalanches, especially in areas with minimal rider compaction or thin variable snow cover.

Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.Avoid steep convexities or areas with a thin or variable snowpack.Avoid lingering in runout zones.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Feb 20th, 2017 2:00PM