Avalanche Forecast

Issued: Mar 27th, 2017 4:12PM

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

triley, Avalanche Canada

South Coast Inland.

The storm forecast for coastal regions is not expected to push very far inland initially. We are uncertain of new snow amounts on Tuesday.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Tuesday

Weather Forecast

Overnight: 3-5 cm of new snow above 1000 metres combined with moderate to strong westerly winds. Tuesday: 3-5 cm of new snow combined with strong westerly winds and daytime freezing levels around 1500 metres. Wednesday: 5-8 cm of new snow combined with moderate southwest winds and daytime freezing levels up to 1600 metres. Thursday: A brief ridge of high pressure should bring light winds and clearing skies, with periods of intense solar radiation.

Avalanche Summary

One report of a cornice collapse in the south of the region on Sunday that resulted in a slab avalanche; the size was not reported due to poor visibility. No new reports of avalanches on Monday.

Snowpack Summary

Steady light snowfalls over last week deposited 25-45 cm of heavily wind affected new snow to the region. Periodic rises in freezing levels to 2000 metres or higher over the same time period have been setting up a series of crust layers (March 20, 22, 23) within the upper snowpack at lower elevations and on solar aspects. A more widespread thick rain crust (March 15) exists up to 2100m and is now buried approximately 45-70cm below the surface. In the north of the region, the February weak layers are 100-140 cm deep and include a buried surface hoar layer as well as a crust/facet layer that appear to be gaining strength. In the southern parts of the region, the mid and lower snowpack are generally well settled and strong.

Problems

Wind Slabs

Light new snow amounts combined with moderate to strong southeast to southwest winds have been building wind slabs. Expect the greatest reactivity in the immediate lee of exposed terrain features and be aware of the potential for cornice triggers.

Use ridges or ribs to avoid pockets of wind loaded snow.Be increasingly cautious as you transition into wind affected terrain.Be alert to conditions that change with elevation.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Cornices

Recent warm and windy weather has been promoting cornice growth. While they are a hazard in themselves, the danger increases with the potential for a cornice fall to trigger a wind slab sitting below it.

Cornices become weak with daytime heating or solar exposure.Pay attention to overhead hazards like cornices.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Mar 28th, 2017 2:00PM