Avalanche Forecast

Issued: Feb 7th, 2018 4:00PM

The alpine rating is high, the treeline rating is high, and the below treeline rating is considerable. Known problems include Persistent Slabs and Wind Slabs.

jasper snow safety, Parks Canada

Jasper.

25-35cm of storm snow expected overnight Wednesday will increase the Avalanche Danger and may require traffic interruptions Thursday for control work on Highway 93N. Maligne Lake Road will be closed Wednesday evening until Friday evening.

Summary

Weather Forecast

Warm, wet, pacific air is meeting cooler arctic air over the forecast area with snowfall intensifying overnight. This system may bring 25-30mm of precipitation with moderate winds and temperatures near -5C. The snowfall event is expected to last into Friday morning when a ridge dominates with cooler temps and blue skies into the weekend.

Snowpack Summary

Moderate SW winds will add the new snow to last week's windslabs in the usual lee locations. Mid-pack persistent weak layers, most notably Jan 7 surface hoar down 40-60cm and rotten Dec 15 facets sitting just below, remain the primary snowpack concern for larger avalanches.

Avalanche Summary

On Monday a sz 3 natural slab avalanche was observed from a thin snowpack area in the Maligne valley on the NE side of Proposal peak at 2500m. Notable avalanches this past week were generally windslabs in the alpine to sz 2.5 and a few persistent slabs in the low alpine and treeline elevation band.

Confidence

Forecast snowfall amounts are uncertain on Wednesday

Problems

Persistent Slabs

Field teams observed whumpfing and moderate test results Sunday and Monday in sheltered zones around treeline on these layers. Shallow areas are the most likely triggering locations in the alpine.

Avoid convexities or areas with a thin or variable snowpack.Watch for whumpfing, hollow sounds, and shooting cracks.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3.5

Wind Slabs

Windslabs were created over the last week with 40cm of snow and West winds. The incoming snow coupled with moderate West winds may build sensitive new storm / windslabs.

Watch for shooting cracks or stiffer feeling snow. Avoid areas that appear wind loaded.If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Valid until: Feb 8th, 2018 4:00PM