Avalanche Forecast

Issued: Apr 23rd, 2014 4:30PM

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

garth lemke, Parks Canada

Jasper.

Assess the new storm snow's bonding to the crust below. Will take few days to bond. Spring conditions exist so start early and end early.

Summary

Weather Forecast

Flurries and cooler temperatures will occur Thursday into Saturday. Freezing levels will reach 2000m in the afternoons and drop overnight continuing the spring cycle.Â

Snowpack Summary

Rain was followed by snow followed by cool temperatures Tuesday evening. Rained up to 2300m. A thin storm slab developed overlying previous temperature crust. Alpine elevations, the snowpack has a solid mid-pack over a faceted base. Cornices are large and ominous. BTL the crust present but deteriorates by the afternoon.

Avalanche Summary

Helibombs on Parkers slab produced size 1-2 storm slabs sliding on crust. A couple of cornice failures noted producing size 3's on steep unskiable terrain (Cromwell and Boundary peak). A couple size 1.5-2.5 solar point releases noted out of steep alpine rocky South bowl features.

Confidence

The weather pattern is stable

Problems

Storm Slabs

Tuesday's storm did not bring a lot of snow yet it was enough to form a thin storm slab. It rests on slippery temperature crust and may have more depth to it where wind loading has occurred. It will meld into the snowpack but give it a few days.

The new snow will require several days to settle and stabilize.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

Cooler temperatures are regulating loose wet avalanches; however, when the sun pokes out, solar aspects can quickly wake up increasing the overall danger. Depending on the overnight freeze, lower elevations will tend to wake up quicker.

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

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

Deep Persistent Slabs

Large triggers such as cornice failures have the potential to initiate deep avalanches. Depending on aspect, could be a wet or dry slab. Consequences would be severe. Be aware of shallow spots as trigger zones and looming cornices about to drop.

Minimize overhead exposure during periods of heavy loading from new snow, wind.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Apr 24th, 2014 4:00PM