Avalanche Forecast

Issued: Mar 3rd, 2018 4:42PM

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

cgarritty, Avalanche Canada

South Rockies.

The sun packs a powerful punch this time of year. Increase your caution around slopes that see direct sunshine on Sunday.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

Sunday: A mix of sun and cloud with greater cloud cover in the east of the region. Light southwest winds. Alpine high temperatures of -10.Monday: Mainly cloudy with isolated light flurries and a trace of new snow. Moderate southwest winds. Alpine high temperatures of -11.Tuesday: A mix of sun and cloud. Light southwest winds, increasing in the afternoon. Alpine high temperatures of -12.

Avalanche Summary

Over the past week there have been reports of both natural and skier triggered loose dry avalanches in steep terrain, as well as skier and explosive triggered storm slab avalanches up to size 1 that were reported on Monday.Last weekend there were two reports of snowmobilers triggering a size 1.5 and size 2 wind slab releases on northeast to east aspects between 2000-2100 m in the Window mountain area.

Snowpack Summary

After 10-25 cm of new snow fell over Friday night, about 25-40 cm of accumulated storm snow now covers previously wind-scoured, westerly slopes and old hard and soft wind slabs on leeward, easterly alpine and treeline slopes. Beneath these old wind slabs lies a well-settled mid-pack. The lower snowpack is generally weak with two primary concerns that are widespread:1) A widespread weak layer from mid-December composed of facets, crusts, and surface hoar that is 100-150 cm deep.2) A rain crust with sugary facets buried in late November near the bottom of the snowpack.

Problems

Storm Slabs

Our new snow will need time to settle and bond to the surface. As it does, natural avalanching will taper off while slabs remain reactive to human triggering. Stick to supported slopes and expect direct sunshine to quickly destabilize the new snow.

Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.Watch for signs of instability such as recent avalanches or shooting cracks.Avoid exposure to steep, sun exposed slopes when the solar radiation is strong.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2.5

Deep Persistent Slabs

Deeply buried weak layers are lingering near the base of the snowpack. These layers are most likely to be triggered from thin or variable snowpack areas or with a large load like a cornice fall.

Avoid steep convexities or areas with a thin or variable snowpack.Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3.5

Valid until: Mar 4th, 2018 2:00PM