Avalanche Forecast

Issued: Feb 6th, 2018 4:00PM

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

landon shepherd, Parks Canada

Jasper.

Incoming storm will increase Avalanche Danger through Wednesday and Thursday

Summary

Weather Forecast

Warm, wet, pacific air is forecast to over-ride the arctic air Wednesday evening. This system may bring 25-30mm of precip with moderate winds and temperatures near -5C. The snowfall event is expected to last through Thursday evening.

Snowpack Summary

Moderate SW winds are adding to last week's windslabs in the usual lee locations. These formed from the 55cm of snow in the Icefields area over the last week. 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 in specific areas.

Avalanche Summary

1 sz 3 natural slab avalanche was observed yesterday in a thin snowpack area in the Maligne valley on the NE side of Proposal peak at 2500m. Yesterday's road patrol noted older avalanches that were generally windslabs in the alpine to sz 2.5 and a few persistent slabs in the low alpine.

Confidence

Intensity of incoming weather systems is 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 where windslabs thin out are likely triggering locations in the alpine.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3.5

Wind Slabs

10-15cm of recent snow is being added to lee features by moderate SW winds. This new snow may also be hiding older stiffer windslabs from last weeks heavier snow and strong SW winds.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2.5

Valid until: Feb 7th, 2018 4:00PM