Avalanche Forecast

Issued: Apr 2nd, 2015 8:00AM

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

danyelle magnan, Parks Canada

Glacier.

A cooling trend is helping to lower avalanche danger but has also brought a return to more wintery problems at higher elevations. New snow, sustained winds, and persistent weak layers mean that there are lots of factors to keep in mind to stay safe.

Summary

Weather Forecast

Thursday and Friday should be mostly dry but we may see a few flurries. Expect a mix of sun and cloud, alpine temps around -10, and moderate westerly winds. A weak storm is expected to arrive later on Friday, bringing increasing cloud and flurries. 9cm of snow are expected on Sat with freezing levels to 1500m.

Snowpack Summary

Temps have cooled off. At 1300m, a skiff of snow overlies a 3cm thick crust which should stay intact today. Above 1800m over 30cm of dry snow overlies a crust. 30cm of wet snow is buried and insulated down 60-100cm. Snowpack tests indicate that these layers may be triggerable by light loads, and if triggered are capable of propagating widely.

Avalanche Summary

No new natural avalanches were observed in Glacier National Park yesterday. Ski cuts produced small sluffs in the new snow on steep slopes at treeline. Wind slabs on lee features in the alpine were reported to be reactive to skier traffic, producing size 1 avalanches.

Confidence

Freezing levels are uncertain

Problems

Wind Slabs

Moderate, but gusty, winds have been shifting from the SW to the NW forming pockets of wind slab in the alpine. Due to the variable wind direction they may exist in unusual places.

Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 2

Storm Slabs

Up to 60cm of new snow exists at higher elevations. This new storm snow will get it's first "kiss from the sun" today, which often triggers avalanches. The storm slabs may be more reactive where they bond poorly to crusts below.

The new snow will require several days to settle and stabilize.Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

A series of weak layers in the top 1.5m of the snowpack are more easily triggered due to the load added by the new snow and rain over the past week. They may be triggered by the added load of a person, another avalanche or a cornice falling.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.Pay attention to overhead hazards like cornices.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Apr 3rd, 2015 8:00AM