Avalanche Forecast

Issued: Apr 1st, 2013 10:33AM

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

jlammers, Avalanche Canada

Northwest Coastal.

Reports of remote triggering suggest the March 9th surface hoar layer is still touchy in some areas. Where it is still reactive, avalanches may be large.

Summary

Confidence

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

Weather Forecast

Tuesday: Very light snowfall with a mix of sun and cloud / Moderate west winds / Freezing level at 800mWednesday: Generally clear in the morning with increasing cloud throughout the day / Light northwest winds / Freezing level at 1200mThursday: Light to moderate snowfall / Moderate west winds / Freezing level at 1200m

Avalanche Summary

In recent days loose wet activity to size 2 has been observed in steeper sun-exposed terrain. Natural cornice releases to size 3 were also noted. A size 1.5 slab avalanche was also remotely triggered from 75m away. I would suspect the March 9th interface was the culprit with this event.

Snowpack Summary

Surface snow has settled with the influence of warm temperatures and surface faceting continues on steep shaded slopes. Solar aspects in the alpine and all lower elevation terrain are now well into a daily melt-freeze cycle with sun-exposed slopes becoming very weak with daytime warming.Between 50-75cm below the surface is layer of surface hoar buried on March 9th which is variably reactive. In some areas it is stubborn and requires a significant trigger. In other areas the layer is still well preserved showing sudden planar or sudden collapse test results, and remains a primary concern among some professional operators.The mid snowpack is generally well settled and strong. Having said that, basal facets may resurface as a concern with spring warming, particularly in the north of the region.Cornices are large and untrustworthy, especially when the sun is out.

Problems

Persistent Slabs

Reports of remote triggering suggest the March 9th surface hoar layer is still touchy in some areas. Where it is still reactive, avalanches can be large and potentially destructive.

Dig down to find and test weak layers before committing to a line.>Be aware of the potential for large avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 5

Loose Wet

The influence of the sun is somewhat uncertain on Tuesday. If the sun is shining expect loose wet sluffs to fail on sun-exposed 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

Possible - Likely

Expected Size

1 - 4

Cornices

Large developed cornices loom over slopes. Possible warming on Tuesday will increase the chances of failure with the potential to initiate large avalanches.

Do not travel on slopes that are exposed to cornices overhead.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 6

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