Avalanche Forecast

Issued: Apr 12th, 2016 8:39AM

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

jsmith, Avalanche Canada

Sea To Sky.

Spring conditions with a brief return to winter in the alpine. Expect to find touchy wind slabs sitting on slippery crusts.

Summary

Weather Forecast

WEDNESDAY: Freezing level: 1500m, cloudy , light to moderate southerly ridgetop winds. THURSDAY: Freezing level: 1900m, mix of sun and cloud,Â light southerly ridgetop winds. FRIDAY: Freezing level: 1500m, cloudy, light southerly ridgetop winds.

Avalanche Summary

On Monday, a size 2.5 cornice triggered avalanche was reported on an east aspect at 2000m near Whistler.

Snowpack Summary

Cornices are large, fragile, and could trigger deep slab avalanches that run to valley bottoms. Monitoring the overnight freeze of the snow surface is very important during the spring. If the snow surface does not freeze overnight or if the crust is only a few cm thick, the effect of daytime heating and solar radiation will weaken the snowpack much more quickly than it would if there is a well frozen thick crust. This is because the crust must first melt before the sun can weaken the snowpack. Deeply buried weak layers in the mid snowpack and near the ground still have the potential to wake up and become active with a rapid warm up. While unlikely, releases on these deeply buried weak layers would result in very large avalanches. Glide cracks are widespread, active, and best avoided. Low elevation and thin snowpack areas have become isothermal, meaning the snowpack is 0 degrees Celsius throughout. An isothermal snowpack is more prone to full depth wet slab avalanches during the heat of the day, especially on steep, rocky faces.

Problems

Wind Slabs

Be on the look out for fresh touchy wind slabs sitting on slippery crusts in the alpine.

Travel on ridgetops to avoid wind slabs on slopes below. >Be cautious as you transition into high elevation wind affected terrain. >

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Cornices

New snow and wind is adding weight to the large and looming cornices in the alpine.

Pay attention to overhead hazards like cornices.>Cornices become weak with daytime heating, so travel early on exposed slopes. >Give cornices a wide berth when traveling on or below ridges. >

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Loose Wet

When the new snow in the alpine is warmed by the sun for the first time natural loose wet avalanches will be soon to follow.

Look for signs of surface instabilities such as pinwheeling and point releasing near cliffs. >Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Apr 13th, 2016 2:00PM