Avalanche Forecast

Issued: Mar 17th, 2017 8:08AM

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

andrew jones, Parks Canada

Glacier.

A slight break in precipitation today but more is on the way this evening. Recently formed storm slabs are still reactive to human triggering.

Summary

Weather Forecast

A low pressure system is building off shore and will arrive at Rogers Pass late this evening. Mainly cloudy for today with freezing levels rising to 1500m and light winds from the south. Expect 14cm of snow tonight with the arrival of the storm. Freezing levels climb to 1800m Saturday with another 22cm of snow and SW winds gusting to 75km/h.

Snowpack Summary

Intense precipitation and strong southerly winds have created touchy storm and wind slabs above treeline. Freezing levels have come down creating a breakable surface crust below treeline with moist/ wet snow below. Weak interfaces in the upper snowpack are still easily trigged by human loading. The late Feb crust interface is now down 1-1.5m.

Avalanche Summary

Natural activity subsided yesterday at higher elevations. Below treeline, small loose wet avalanches were observed next to the highway corridor. A field team ski cut a size 1.5 storm slab on a steep SE facing roll at 2000m. Newly formed storm and wind slabs remain reactive and will once again fail naturally with the forecasted precipitation .

Confidence

Problems

Storm Slabs

Heavy precipitation combined with wind and warm temperatures have formed reactive storm slabs at all elevations. Although natural avalanche activity has subsided, these slabs remain triggerable by human loads!

The new snow will require several days to settle and stabilize.If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3

Persistent Slabs

Persistent deep layers made a triumphant return during our most recent avalanche cycle and they remain a cause for concern. As surface instabilities fail, avalanches can easily step down weak layers from late February.

Watch for whumpfing, hollow sounds, and shooting cracks.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

3 - 4

Loose Wet

Recent rain events have saturated the snowpack at lower elevations. Although a thin surface crust formed from last night's cooler temperatures, it does not add enough strength to eliminate the problem of loose wet avalanches below tree line.

If triggered the loose wet sluffs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Mar 18th, 2017 8:00AM