Avalanche Forecast

Issued: Mar 31st, 2013 9:27AM

The alpine rating is considerable, 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.

Be alert to conditions that change with daytime warming. Danger ratings are likely to exceed posted levels if solar radiation is strong.

Summary

Confidence

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

Weather Forecast

Monday: High cloud / Moderate southwest winds / Freezing level at 2000mTuesday: Very light snowfall / Moderate west winds / Freezing level at 900mWednesday: Overcast skies / Moderate west winds / Freezing level at 1100m

Avalanche Summary

In recent days loose wet activity to size 2.5 has been observed in steeper sun-exposed terrain. On Friday a skier-triggered size 1 slab occurred on a solar aspect on March 9th surface hoar. This avalanche remotely triggered a 2nd slab (150m away) lower down in a similar terrain feature again on the March 9th layer.

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 showing sudden planar or sudden collapse test results with the potential for large avalanches. Check out the Forecaster's Blog for related discussion.The mid and lower snowpack are 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

In some areas the March 9th layer can still be triggered and propagate across large distances creating surprisingly large avalanches.

Be aware of the potential for large avalanches due to the presence of buried surface hoar.>Avoid areas with overhead hazard.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 6

Loose Wet

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

Likely

Expected Size

1 - 4

Cornices

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

Cornices become weak with daytime heating, so travel early on exposed slopes.>Pay attention to overhead hazards like cornices.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 6

Valid until: Apr 1st, 2013 2:00PM