Avalanche Forecast

Issued: Apr 20th, 2016 8:00AM

The alpine rating is below threshold, the treeline rating is below threshold, and the below treeline rating is below threshold. Known problems include Loose Wet, Wet Slabs and Cornices.

chris gooliaff, Parks Canada

Glacier.

Early starts and early finishes are the safe way to travel in the mountains right now. The mid-summerly weather is rapidly changing conditions daily.

Summary

Weather Forecast

The heat continues, with freezing levels hovering around 3700m, intense sunshine, and calm to light winds at ridge-top. Clouds will begin to roll into the area tomorrow, with showers expected Thursday through Saturday. The freezing level will finally drop to ~2000m later on Saturday.

Snowpack Summary

The melt-freeze crust on slopes over 30* at tree-line and alpine elevations is thinner and weaker with the warm overnight temp's. This will break down rapidly with the record heat wave. Below tree-line, the snowpack is isothermal and loses all strength with the daytime warming. Northerly aspects in the high alpine still sport dry snow.

Avalanche Summary

A natural avalanche cycle late in the afternoon/evening yesterday saw deeper slabs failing, some to ground, on Tupper and MacDonald. Deep, wet slabs were also observed from S-facing aspects on Bagheera and Catamount. Expect glide-cracks to become more active, which are opening up on many slopes and can fail unpredictably.

Confidence

Problems

Loose Wet

Warmer temp's are preventing a strong surface crust to refreeze at night. This crust is holding everything together on the mountain. When the crust has broken down, loose wet avalanches will be easy to trigger and can entrain significant mass.

Start and finish early before the surface crusts melt.Use extra caution on slopes if the snow is moist or wet.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Wet Slabs

With the warms temps & strong solar radiation, avalanche activity will surely increase. Without a strong overnight freeze the snowpack will warm & lose its structure. As this happens it will sporadically fail as large destructive wet slab avalanches

Avoid exposure to overhead slopes with Glide Cracks. Avalanches may reach the end of run out zones.Use extra caution on solar slopes, or if the snow is moist or wet.

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3

Cornices

Cornices are sagging and are precariously perched on high alpine ridges. Sun and continued warmth will further weaken them.

Give cornices a wide berth when travelling on or below ridges.Cornices become weak with daytime heating, so travel early on exposed slopes.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Apr 21st, 2016 8:00AM