Avalanche Forecast

Issued: Apr 21st, 2013 10:31AM

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

swerner, Avalanche Canada

South Columbia.

The Public Avalanche Forecasts will come to an end on Monday. Starting Tuesday you can find spring messaging under the "Forecast Details" tab below.See you next Season!

Summary

Confidence

Fair - Due to limited field observations

Weather Forecast

An upper ridge stalls off the coast bringing sunny skies and dry cool conditions through Tuesday. By mid-week freezing levels will rise to 2000 m.Monday: Mostly sunny with some broken clouds further South. Flurries in the most southern parts of the region and nil further North. Ridgetop winds will blow light from the North and freezing levels will rise to 1500 m. Tuesday: Broken cloud cover and a chance of flurries. Ridgetop winds moderate from the NW and freezing levels will rise to 1700 m. Wednesday: The stationary ridge of high pressure continues bringing sunny skies and freezing levels up to 2000 m. Ridgetop winds will blow light from the SW.

Avalanche Summary

No new avalanche activity reported.On Friday, reports of the new storm snow was sluffing from steep terrain up to size 2. With rising freezing levels and sunny skies, conditions can change quickly and avalanche danger will rise.

Snowpack Summary

At higher elevations up to 25 cm of new snow sits on a series of melt-freeze crusts (solar aspects) and some smaller surface hoar crystals (northerly aspects). Wind slabs exist on lee slopes and behind terrain features. Cornices are huge and will likely become weak with daytime warming. They threaten slopes below. Surface snow will likely become wet and deteriorate on solar aspects.Deeper in the snowpack (60-120 cm down) a weaker interface exists comprising of crusts, and surface hoar. Earlier this week, very large avalanches were reactive on this interface in the neighboring region. Be cautious and remain suspicious of steeper, high alpine slopes.

Problems

Wind Slabs

Wind slab problems exist on lee slopes and behind terrain features at treeline and above. Huge cornices exist on ridgelines, they will likely become weak with daytime warming and solar radiation.. Keep well back and watch your overhead hazards.

Use ridges or ribs to avoid pockets of wind loaded snow.>Cornices become weak with daytime heating, so travel early on exposed slopes.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Loose Wet

Loose wet avalanche activity is likely with rising freezing levels and clear sunny skies. Conditions can change quickly with timing, aspect and elevation.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

Last weak an interface buried down about 60-120 cm created surprisingly large avalanches in neighboring regions. Smaller avalanches, cornice fall or the weight of a person hitting a thin-spot, may trigger a large & destructive avalanche.

Conditions are greatly improved, but be mindful that deep instabilities are still present.>Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

1 - 6

Valid until: Apr 22nd, 2013 2:00PM