Avalanche Forecast

Issued: Apr 3rd, 2017 3:35PM

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

shorton, Avalanche Canada

Northwest Coastal.

Increasing cloud and wind on Tuesday as a storm approaches the coast. Watch for reactive slabs in steep or wind loaded terrain.

Summary

Confidence

High -

Weather Forecast

TUESDAY: Overcast with snow starting midday and about 5 cm by the end of the afternoon, south wind increasing to 50-80 km/h, freezing level up to 1200 m.WEDNESDAY: 15-25 cm of new snow, strong south wind, freezing level around 1200 m.THURSDAY: Linger flurries with another 5-15 cm, moderate southwest wind, freezing level dropping to 700 m.

Avalanche Summary

On Sunday, a few recent natural storm slabs were reported (up to size 2), mostly sliding on 20-30 cm deep crusts. A few cornice falls and loose dry avalanches were reported as well. Recent storm snow may remain reactive to human triggers, especially as wind speeds increase on Tuesday.

Snowpack Summary

20-30 cm of recent storm snow is settling at higher elevations. Thick supportive crusts are forming overnight below 1300 m and deteriorating throughout the day with warming. The snow below treeline may become weak and release as loose wet avalanches in steep unsupported terrain features. The late February persistent weak layer continues to be a concern for triggering large avalanches. This combination of crust and weak facets is now down 100-150 cm, and may be triggered by light loads in shallow weak spots.

Problems

Wind Slabs

Recent storm snow may still be reactive on steep convexities and on wind loaded terrain features at higher elevations.

Use caution on open slopes and convex rolls If triggered, the wind slabs may step down to deeper layers resulting in large avalanches.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

A weak layer from February remains a concern. It produced several large human triggered avalanches at the end of March, and may still react in shallow areas. Heavy loads such as a storm slab avalanche or a cornice fall are also possible triggers.

Avoid steep convexities or areas with a thin or variable snowpack.Remote triggering is a concern, watch out for adjacent slopes.Carefully evaluate big terrain features by digging and testing on adjacent, safe slopes.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Apr 4th, 2017 2:00PM