Avalanche Forecast

Issued: Mar 28th, 2013 10:41AM

The alpine rating is low, the treeline rating is low, and the below treeline rating is low. Known problems include Loose Wet and Cornices.

mpeter, Avalanche Canada

Sea To Sky.

Danger could INCREASE TO CONSIDERABLE with intense radiation on south and west aspects. Be aware of how the warm weather is changing the snowpack.

Summary

Confidence

Good

Weather Forecast

Friday: Spring continues! Expect mostly clear skies and warm temperatures. Winds should be light northerly with alpine temperatures reaching 5.Saturday/Sunday: The high pressure system persists with more warm, clear and calm weather. Winds remain light northerly and temperatures climb a few degrees warmer each afternoon. Freezing levels could peak at 2700m in the afternoons and it is possible that Saturday night will not see a refreeze.

Avalanche Summary

Loose wet sluffs up to size 2.0 have been reported on south and west aspects. Isolated large cornice falls have also been reported; none of these recent cornice events have pulled slabs on the slopes below.

Snowpack Summary

Recent warm temperatures have created melt freeze crusts up to 2000m on all aspects and well into the alpine on south and west facing terrain. These crusts break down with daytime warming and the surface snow can lose cohesion as a result. The odd lingering windslab remains reactive on high, north facing slopes, but these have largely broken down due to near surface facetting from cool overnight temperatures. Cornices are huge! Various melt-freeze crusts are buried in the upper snowpack. In general, the bond at these interfaces is good. A layer of surface hoar (buried on March 11; now down about 90 cm) is still being observed in some locations, with hard results in snowpack tests. Mid and lower snowpack layers are well bonded.

Problems

Loose Wet

Direct sun may trigger loose snow avalanches on steep sunny slopes.

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

Very Likely

Expected Size

1 - 4

Cornices

Cornices are large and weak. Daytime warming and/or direct sunshine could cause cornices to fail, possibly triggering a slab on the slope below.

Cornices become weak with daytime heating, so travel early on exposed slopes.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 6

Valid until: Mar 29th, 2013 2:00PM