Avalanche Forecast

Issued: Apr 3rd, 2014 9:26AM

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

triley, Avalanche Canada

South Rockies.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain on Friday

Weather Forecast

Overnight and Friday: Freezing level dropping to about 1500 metres overnight and then rising to 2000 metres during the day. Strong Southwest winds combined with light precipitation overnight and during the day.Saturday: Winds becoming more Westerly as the light precipitation continues. Freezing levels rising to 2000 metres during the day.Sunday: Chance of moderate precipitation overnight combined with moderate Westerly winds. Freezing levels rising to 2000 metres during the day.

Avalanche Summary

No new avalanches reported. I suspect that loose moist or wet snow may release naturally on solar exposed terrain. Cornices have been reported to be very large and may be weakened by exposure to the strong sun of April.

Snowpack Summary

Solar radiation and high freezing levels have created new melt-freeze crusts on Southerly aspects. The 20-40cm of recent new snow sits on top of a thick sun crust on solar aspects. 70-90 cm of settling storm snow from the past week rests on a graupel layer that can be found in much of the region. This makes for around 90 cm on top of the mid march crust at this point. This crust exists on all aspects below 2000m and on solar aspects in the high alpine. North of Sparwood and in the Crowsnest Pass area, the buried crust seems more specific to previously sun-exposed slopes. The deep facet/crust persistent weakness buried at the beginning of February (now down 140 to 170cm) seems unlikely to trigger in areas where the hard, supportive crust exists. No matter where you are in the region, this weakness should stay on your radar as any activity at this interface would be large and destructive. Possible triggers include a large cornice fall, a large input in a thin snowpack area or solar warming.

Problems

Wind Slabs

Forecast Southwest winds may continue to transport snow into pockets of wind slab on lee slopes. Weak cornices may continue to develop new growth that may be easy to trigger.

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

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Deep Persistent Slabs

Avalanches releasing on the deeply buried weak layer from early February are still a concern. Strong solar radiation, cornice falls, new loading, or storm slab avalanches in motion are all possible triggers.

Caution around convexities or areas with a thin or variable snowpack.>Consider the consequences of the terrain if an avalanche steps down to a persistent weakness.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Apr 4th, 2014 2:00PM