Avalanche Forecast

Issued: Mar 22nd, 2013 10:20AM

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

triley, Avalanche Canada

South Columbia.

Expect conditions to be very aspect dependant. It is Winter on Northerly aspects with dry snow and very large cornices. And it is Spring on Southerly aspects with moist snow above old crusts.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Saturday

Weather Forecast

Overnight and Saturday: Mostly clear overnight with alpine temperatures dropping down to -13.0. Light Easterly or Northeasterly winds are expected. Freezing levels rising to about 1200 metres during the day.Sunday: A ridge of High pressure will be centered over the Interior ranges bringing Light Southwest winds and daytime highs of about -6.0 in the alpine. Strong solar radiation and freezing levels rising to about 1400 metres.Monday: The ridge is expected to move Eastwards during the day, but mostly sunny conditions should continue during the day.

Avalanche Summary

There were many skier controlled and skier accidental avalanches up to size 1.5 that were reported on Thursday.

Snowpack Summary

Moist snow may be found on solar aspects up to about 2200 metres. New melt/freeze crusts are developing due to cold clear nights and strong solar radiation during the day. The recent storm amounts are between 40-80 cms at higher elevations. Strong winds overnight and early Wednesday morning developed thick pockets of wind slab at higher elevations. Cooling temperatures have promoted bonding to the moist snowpack at lower elevations. New cornice growth is reported to be extensive and weak. Expect natural cornice falls that may trigger weak layers that are buried down a metre or more on slopes below. The new storm load may trigger the March 10th weak surface hoar layer.

Problems

Storm Slabs

Recent storm slabs and wind slabs may continue to be triggered by light additional loads. New cornice growth may be extensive and weak. Cornice falls may trigger deeply buried weak layers.

The new snow will require several days to settle and stabilize.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Extra caution needed around cornices with current conditions.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

The March 10th weak layer of surface hoar is buried down more than a metre in most places. Large loads like cornice falls may trigger this deeply buried weak layer.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Mar 23rd, 2013 2:00PM