Avalanche Forecast

Issued: Mar 7th, 2018 5:10PM

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.

jsmith, Avalanche Canada

South Rockies.

Forecast warming and sunshine over the weekend will stress the snowpack and increase hazard.

Summary

Confidence

High -

Weather Forecast

THURSDAY: Mix of sun and cloud / Moderate to strong southwesterly ridgetop winds / Freezing levels rising to around 1500 m. FRIDAY: Mostly cloudy / Moderate westerly ridgetop winds / Freezing level around 1600m.SATURDAY: Mostly sunny / Light southwesterly ridgetop winds / Freezing level rising to around 1800 m.

Avalanche Summary

Explosive control work northwest of Elkford on Tuesday produced numerous size 3 persistent slab avalanches failing on facets near the base of the snowpack. The most notable results were on steep, rocky north aspects, and lower angled west aspects.

Snowpack Summary

Sun crusts on solar aspects with generally better riding conditions on north and east aspects. Accumulated storm snow from last week totals 25-40cm. This new snow 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 the primary concern being a combination of crusts and facets near the bottom of the snowpack that are widespread. The primary concern looking ahead towards the weekend and early next week is the potential of these deeper persistent weak layers becoming active by rapid warming of the snowpack through rising freezing levels and intense solar radiation.

Problems

Wind Slabs

Wind slabs are becoming less likely to human trigger. Steep, convex, and rocky areas are the most likely spots to trigger these lingering winds slabs.

Use ridges or ribs to avoid pockets of wind loaded snow.Be aware of the potential for wide propagations due to the presence of hard windslabs.Watch for newly formed wind slabs as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 1.5

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.

Extra caution needed around cornices with current conditions.Avoid steep convexities or areas with a thin or variable snowpack

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely

Expected Size

2 - 3.5

Valid until: Mar 8th, 2018 2:00PM