Avalanche Forecast

Issued: Nov 25th, 2015 8:19AM

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

Avalanche Canada swerner, Avalanche Canada

The snowpack is extremely variable depending on aspect and elevation and does not adjust well to rapid change. Watch for rising temperatures to well above 0 degrees. Check out the Mountain Information Network. Give info, get info!

Summary

Confidence

Poor - Due to the number and quality of field observations

Weather Forecast

The high pressure ridge continues to dominate the coastal regions. Strong alpine temperature inversions will be prominent and freezing levels will be rising to 2400 m. Moderate to strong outflow winds will prevail in coastal valleys especially in the overnight and early morning. Valley cloud may accompany the strengthening temperature inversion. By Sunday the weather pattern may see a change, however; timing and intensity of the next Pacific system is hard to pin point due to disagreement between the Canadian model and the GFS.

Avalanche Summary

On Tuesday, a size 1 skier triggered slab was reported from an east aspect @ 1900 m as well as numerous natural wind slab avalanches from southerly aspects up to size 1.5. I suspect these stiff wind slabs may remain sensitive to rider triggers and as the warm air aloft invades the region watch for obvious clues like natural avalanche activity and moist/ wet snow surfaces, especially on southerly slopes. Smaller avalanches may also trigger deeper layers beneath the the surface, initiating larger avalanches.

Snowpack Summary

Monday's 20 cm of storm snow has seen some serious effects from the recent winds and cold temps. Northerly winds have likely built stiff wind slabs on southerly slopes and stripped snow from exposed aspects. These wind slabs may have a poor bond to the old surfaces that comprise of surface hoar, crusts (potentially up to 2100 m) and some dry facetted snow above that. Strengthening temperature inversions at upper elevations may start to deteriorate the upper snowpack, especially on southerly aspects. Watch for obvious signs of instability like moist and/or wet snow surfaces and snow balling. Where the buried crust is thick, avalanches failing on deeper layers beneath have become much less likely. My uncertainty lies at higher elevations where the buried crust doesnt exist and deeper persistent weak layers may. Reports indicate that these shears are resistant in the moderate to hard range with sudden fracture characteristics. I'd remain extra cautious as they may be sensitive to rider triggering.

Problems

Wind Slabs

An icon showing Wind Slabs
Stiff wind slabs, especially on southerly aspects will likely have a poor bond to the old snow surfaces and may remain sensitive to rider triggers.
Be alert to conditions that change with elevation and use a cautious approach to terrain while gathering information along the way.>Stay off recent wind loaded slopes and behind terrain features.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Loose Wet

An icon showing Loose Wet
Strengthening warm air aloft (above 1000 m) may deteriorate snow surfaces initiating loose wet avalanches. Smaller avalanches could dig down to deeper layers, especially at higher elevations, initiating larger slab avalanches.
Watch for clues that indicate that the snowpack is warming up, like sluffing off of cliffs, snow balling and natural avalanche activity.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Nov 26th, 2015 2:00PM