Avalanche Forecast

Issued: Feb 20th, 2017 8:02AM

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.

chris gooliaff, Parks Canada

Glacier.

Good skiing can be found in the alpine, but be aware of hidden wind slabs near the top of your line. Also, keep an eye on all of the other people above/below you. There are a lot of folks enjoying the Rogers Pass backcountry!

Summary

Weather Forecast

A benign forecast for the week. Mix of sun and cloud today with isolated flurries bringing trace amounts of snow. Winds should be light from the SW and freezing levels may rise to 1500m by the afternoon. More of the same throughout the rest of the week, with temp's dropping in the alpine to the mid minus-teen's by Wednesday.

Snowpack Summary

Convective clouds and little wind the past 2 days have brought 10-15cm of new snow to the area. This has covered wind slabs at ridge-top elevations and a frozen, rain-soaked surface below tree-line. The biggest layers of concern are down 30-60cm, and are crusts on S aspects and surface hoar on sheltered N slopes.

Avalanche Summary

Several size 1.5-2 slabs from steep, N-facing terrain on Mt Macdonald were observed yesterday. Saturday, whumphing and cracking was observed in the alpine along shallow, wind-blown S/SW aspects at ridge-top.

Confidence

Problems

Wind Slabs

Strong S winds from several days ago left wind slabs at ridge-top and on exposed alpine features. These are bonding to the upper snowpack but are still reactive on unsupported features. Brief sunny breaks may wake up these slabs on the buried crusts.

Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

Weak layers in the top meter include sun crust on solar slopes and pockets of surface hoar. Tests show isolated sudden planar results, making them hard to predict. Be cautious in shallow snowpack areas (ridge-crests) where triggering is more likely.

Watch for whumpfing, hollow sounds, and shooting cracks.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Feb 21st, 2017 8:00AM