Avalanche Forecast

Issued: Feb 18th, 2017 8:06AM

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

ian gale, Parks Canada

Glacier.

Expect variable conditions as you transition from warm temperatures below tree line to new wind affected snow in the alpine. If freezing levels rise rapidly or it rains, expect avalanche hazard to rise

Summary

Weather Forecast

Today will be a mainly cloudy day and ridge wind will be light from the SE. It was cool overnight with temps down to -5, but freezing level is forecast to reach 1800m today. A low pressure system over Oregon will spread light precip into our area this afternoon and overnight.

Snowpack Summary

20-40 cm of storm snow sits on top of a strong temperature or sun crust. At higher elevations where sheltered from sun and wind, the storm snow buries surface hoar. Mod to strong south winds have formed windslabs at ridgetop. At lower elevations, rain has soaked the upper snowpack and now below freezing temps have frozen a crust on the surface.

Avalanche Summary

Warm temperatures, precipitation and strong winds contributed to an ongoing widespread natural moist/wet avalanche cycle in the last 48hrs, 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

Freezing levels are uncertain

Problems

Wind Slabs

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

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

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 2

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.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Loose Wet

With high freezing levels today and moist snow on the surface, loose wet avalanches are expected today. 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 19th, 2017 8:00AM