Avalanche Forecast

Issued: Mar 5th, 2015 8:07AM

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

rbuhler, Avalanche Canada

South Rockies.

Conditions are generally stable but be cautious of lingering pockets of wind slabs in the alpine as well as sluffing from steep sun exposed slopes during the afternoon.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

The ridge should keep the region dry and mainly clear through the weekend. On Friday, a mix of sun and cloud is expected with freezing levels climbing to around 2000m. Alpine winds are expected to be moderate-to-strong from the NW. On Saturday, similar conditions are expected with a mix of sun and cloud, freezing levels around 2000m, and light-to-moderate W-NW winds in the alpine. Sunday looks to be mainly sunny and freezing levels could get as high as 2500m.

Avalanche Summary

No new avalanches have been reported recently. Natural avalanches are generally not expected on Friday but small human-triggered avalanches remain possible in isolated areas, specifically wind-loaded areas of the alpine.

Snowpack Summary

In sheltered areas, up to 10 cm of new snow from earlier in the week sits over a previously variable snow surface which was a mix of surface hoar, crusts, wind affected surfaces, and/or dry powder. Ongoing winds have redistributed the new snow in wind-exposed terrain resulting in a highly variable snow surface and the formation of thin wind slabs in leeward features. The most prominent snowpack feature is a thick supportive crust around 10-30 cm below the surface. It extends up to around 2200m elevation. Below this elevation the crust is effectively capping the snowpack, preventing riders from stressing deeper persistent weak layers. In alpine areas where the crust is not present or is less thick, it could still be possible to trigger a deep avalanche from rocky sun-exposed slopes, thin snowpack areas, or with a heavy load (i.e. cornice fall).

Problems

Wind Slabs

Recent light snowfall and moderate winds from variable directions have created pockets of thin wind slab in exposed leeward terrain features.

Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Persistent Slabs

Deeper weaknesses still exist and remain a concern in shallow rocky areas or anywhere the thick near-surface crust is weakening or non-existent, specially north aspects above 2200m.

Be aware of thin areas and rock outcroppings where it may be possible to initiate an avalanche that fails on one of the deeply buried weak layers.>

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

3 - 6

Valid until: Mar 6th, 2015 2:00PM