Avalanche Forecast

Issued: Jan 17th, 2013 4:00PM

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

A.L. Horton, Parks Canada

Jasper.

Intense solar radiation or precipitation in the form of rain will rapidly increase the avalanche hazard at lower elevations.

Summary

Weather Forecast

Temperatures will remain mild and skies will be broken on Friday. Winds will be moderate NW easing to light late in the day. Precipitation amounts vary from a trace in Jasper Townsite to a possible 10 cm in the Icefields area.

Snowpack Summary

Snowpack remains thin and facetted at lower elevations, but is supportive above tree line. Last week's storm snow has buried a surface hoar layer (Jan6) down approx 30cm. A variety of wind slabs are building on lee alpine, tree line and on open slopes below tree line from moderate to strong southwesterly winds.

Avalanche Summary

Natural slab activity to size 2.5 was observed at treeline and alpine elevations where the new wind slabs released on the January 6th surface hoar layer. Although they did not travel far, they did step down to the basal facets and November rain crust layers.

Confidence

Forecast snowfall amounts are uncertain on Friday

Problems

Wind Slabs

Hard and soft slabs continue to build on a variety of aspects from moderate to strong winds. Natural slab avalanches have initiated on the surface hoar layer and then stepped down to either the basal facets or the November rain crust.

Be careful with wind loaded pockets while approaching and climbing ice routes.Caution in lee and cross-loaded terrain near ridge crests.

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

Wind slabs and loose snow avalanches have triggered this weakness. These avalanches have gained significant mass as a result. This situation will more likely occur in shallow snowpack areas.

Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3

Loose Dry

Wind and warming temperatures are triggering point releases, most commonly out of steep and rocky terrain.

Avoid travelling on ledges and cliffs where sluffing may have severe consequences.Sluffs may trigger deeper instabilities.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 18th, 2013 4:00PM