Avalanche Forecast

Issued: Feb 18th, 2015 7:32AM

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

Peter, Avalanche Canada

South Columbia.

The snow is best up high, but this is also where lingering avalanche concerns exist. Please become a member of Avalanche Canada today at avalanche.ca/membership.

Summary

Confidence

Good

Weather Forecast

The ridge of high pressure flattens on Thursday allowing a couple weak disturbances to cross the province. We should see more cloud with possible light flurries each day. The freezing level is around 1500-1700 m on Thursday and should lower to around 1000-1200 m by Saturday. Winds are light gusting moderate from the W-NW. The ridge rebuilds on Friday but we might not see full clearing until late Saturday. After this it looks like at least a few more days of dry and sunny weather.

Avalanche Summary

For the past few days we have seen a few size 2-3 natural and explosive triggered slabs and cornice failures (sometimes triggering slabs and sometimes not) each day. Almost all of these have been from steep alpine terrain on a variety of aspects. On Tuesday there were also a few reports of loose wet slides from very steep south-facing slopes in the alpine.

Snowpack Summary

The snow surface is a mix of surface hoar, crusts, low density snow, or wind affected snow depending on aspect and elevation. The "Valentine's Day" crust is just below the surface and is now strong and thick in most places. At alpine elevations, new wind slabs may have formed from NW winds, and cornices are large and weak. The late-Jan crust/surface hoar layer (up to 100 cm deep) and the mid-January surface hoar (80-120 cm deep) continue to give variable results in snowpack tests. Chances of triggering these weaknesses have decreased, but triggering may be possible from thin or rocky snowpack areas; or perhaps with a cornice fall, or an avalanche stepping down, especially on sun drenched slopes.

Problems

Wind Slabs

Thin fresh wind slabs can be found behind ridges and terrain features but may be limited to certain areas and/or elevation bands. Cornices are also large and weak and should given a wide berth.

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, South.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

Persistent slabs are most likely to be triggered from thin snowpack areas, or with large triggers like cornice fall or an avalanche stepping down.

Avoid steep slopes below cornices.>Avoid common trigger points like convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

3 - 6

Valid until: Feb 19th, 2015 2:00PM