Avalanche Forecast

Issued: Mar 20th, 2018 4:25PM

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

swerner, Avalanche Canada

Northwest Coastal.

The best skiing and riding conditions are likely found on northerly aspects at upper elevations. Pay attention to changing conditions if the sun comes out.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain on Thursday

Weather Forecast

Wednesday: Mix of sun and cloud with light precipitation. Alpine temperatures near -1.0 and freezing levels at valley bottom. Ridgetop winds light gusting strong from the northeast. Thursday: 10-20 cm of new snow in upper elevations accompanied by strong ridgetop winds from the East. Freezing levels near 500 m and rising through the day to 1200 m. Friday: Cloudy with isolated flurries. Alpine high of -3 and freezing levels near 700 m. Light winds from the East.

Avalanche Summary

On Monday, we received reports of a skier triggered size 1 wind slab on a north-east aspect near 1600m elevation. The slab averaged 20cm thickness and ran on the March 9th surface hoar / facet layer.Last weekend, the region was active with a range of reports from large size 3 wet slabs which stepped down to the mid-December ice layer to a remotely triggered persistent slab (size 2), which stepped down to the mid-January surface hoar interface, running on an east aspect near 1600m.

Snowpack Summary

The snowpack consists of a wide variety of snow surfaces, including up to 20 cm of new snow at higher elevations, pockets of wind slab, a melt-freeze crust on south-west aspects an wet snow down low, On March 9th, surface hoar and/or smaller facets (on sheltered, shady aspects) were buried by the last significant snowfall down 10-25 cm. This layer was reactive to skier triggers in some areas on Monday. Deeper in the mid-pack, layers of crusts, facets, and isolated surface hoar buried 50 to 100 cm exist from mid- and late-February and a surface hoar/ crust layer from January is buried around 150 to 200 cm. Near the bottom of the snowpack, sugary facets exist in colder and dryer parts of the region, such as the far north.

Problems

Storm Slabs

New snow may bond poorly to the old snow surface, especially if it's a firm sun crust or hard wind slab. Smaller avalanches may trigger a deeper surface hoar layer buried March 9th. Uncertainty remains around the distribution of this layer.

Watch for signs of instability such as avalanche activity, whumpfing, hollow sounds or cracking.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2.5

Loose Wet

The sun can really pack a punch this time of year. Avoid solar slopes that become moist or wet.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Mar 21st, 2018 2:00PM