Avalanche Forecast

Issued: Apr 24th, 2014 8:00AM

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

danyelle magnan, Parks Canada

Glacier.

An unsettled forecast could bring intense periods of sun and intense periods of rain, both of which will increase danger.

Summary

Weather Forecast

Expect increasing cloud this afternoon. Moderate precip, with freezing levels of 1800m, will bring 5cm to the alpine and up to 7mm of rain at lower elevations are forecast. Alpine temps might reach 1'C. Friday looks like there will be a mix of sun and cloud, with alpine temps of 3'C and freezing levels of 2100m. Sat another wet storm arrives.

Snowpack Summary

Over the last 48hrs, 15cm of snow fell above 1900m. This snow insulated wet, rain saturated snow preventing it from freezing. At lower elevations, a weak freeze will break down quickly. Several crusts in the top meter of the snowpack provide potential failure layers and sliding surfaces for avalanches. SW winds yesterday formed new windslabs.

Avalanche Summary

On Tuesday, warm temps and light rain triggered 12 wet avalanches up to size 2.5 in the highway corridor. Yesterday, cooler temps helped to tighten the snowpack and there were no new avalanches.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Problems

Wind Slabs

Windslabs in lee features will have formed yesterday with moderate SW winds transporting the new snow. These windslabs overlie various surfaces; at treeline they will likely bond poorly to crusts of wet snow below them.

Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

A 2cm surface crust formed overnight, supporting the weight of a person. This crust will break down rapidly if the sun comes out today, especially at low elevations and on solar aspects.

Start and finish early before the surface crusts melt.Make your travel plans to take advantage of overnight freezing.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

As the upper snowpack becomes isothermal, buried layers like the various March sun crusts and deeply buried surface hoar from February will become failure planes for the wet snow to slide upon.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 4

Valid until: Apr 25th, 2014 8:00AM