Avalanche Forecast

Issued: Apr 13th, 2016 10:36AM

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

jsmith, Avalanche Canada

South Rockies.

Spring conditions with a brief return to winter in the alpine. The forecasted snow with strong winds on Thursday may create fresh thin wind slabs on lee features in the alpine by the end of the day.

Summary

Weather Forecast

THURSDAY: Freezing level: 1700m, 10-15mm of precipitation, moderate to strong easterly ridgetop winds. FRIDAY: Freezing level: 2100m, mix of sun and cloud, light to moderate westerly ridgetop winds. SATURDAY: Freezing level: 2500m, mostly sunny, light westerly ridgetop winds.

Avalanche Summary

No new avalanches were reported in this region on Tuesday. However, the convective flurries and strong easterly winds that are forecasted for Thursday may create fresh thin wind slabs by the end of day.

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.

Problems

Cornices

Cornices have a nasty habit of running surprisingly long distances.

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 travelling on or below ridges. >

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

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

3 - 5

Wet Slabs

Warm temperatures could lead to destructive wet slabs, especially if there is little or no overnight surface refreeze.

Avoid slopes with glide cracks.>Avoid rocky, shallow, and/or steep slopes during the heat of the day.>Parking, eating lunch, and regrouping in runout zones is bad practice.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

3 - 6

Loose Wet

Solar radiation in the spring can rapidly change the hazard from low to high. Plan ahead and monitor the effect of solar radiation carefully.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely

Expected Size

1 - 3

Valid until: Apr 14th, 2016 2:00PM