Avalanche Forecast

Issued: Feb 17th, 2017 8:01AM

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

Andrew Jones, Parks Canada

Glacier.

Expect variable conditions as you transition from warm temperatures below tree line to new wind affected snow in the alpine. The presence of sunshine could increase avalanche hazard at all elevations.

Summary

Weather Forecast

A building ridge of high pressure will block precipitation today and deliver a mix of sun and cloud. Freezing levels are dropping and are expected to stay below 1400m today. Ridge winds will be moderate from the SW. A low pressure system moving through the area tomorrow will bring more light precipitation with another 7cm of snow for the weekend.

Snowpack Summary

7cm of new snow fell last night bringing the 3-day total to 30cm in the alpine. At lower elevations, we have had periods of rain. Storm snow at higher elevations sits atop a suncrust on solar aspects and surface hoar in areas sheltered from sun and wind. The top 20-50cm of snow is moist on all aspects to TL.

Avalanche Summary

Warm temperatures, precipitation and strong winds contributed to a widespread natural moist/wet avalanche cycle yesterday, especially at lower elevations. Avalanches were generally in the size 2-2.5 range, however there were some avalanches running up to size 3 in the highway corridor off of Mt MacDonald.

Confidence

Problems

Wind Slabs

Strong southerly winds (up to 84km/h) blew throughout the overnight period creating touchy wind slabs on northerly aspects and exposed areas above tree line.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Be aware of the potential for wide propagations due to the presence of hard windslabs.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

Weak layers in the top meter include sun crust on solar slopes and pockets of surface hoar. Snowpack tests show isolated sudden planar results, making them hard to predict. With the added load of rain/heavy snow they may be more reactive.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.Watch for signs of instability such as whumpfing, or cracking.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Loose Wet

With up to 50cm of moist snow on the surface, loose wet avalanches are expected today and may be triggered by light loads such as skiers and even tree bombs. Although likely to be small, wet avalanches are powerful and can occur even on small slopes.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Feb 18th, 2017 8:00AM