Avalanche Forecast

Issued: Jan 24th, 2015 8:00AM

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

andrew jones, Parks Canada

Glacier.

Storm snow on existing weak layers means high avalanche danger. Give new snow time to stabilize. Highway avalanche control is planned in Rogers Pass today.

Summary

Weather Forecast

Precipitation will ease off today with a short period of high pressure. Southerly winds will remain strong and freezing levels will rise to 1800m. A series of passing fronts will bring periods of light precipitation and gusting winds over the next couple of days. Freezing levels are expected to spike on Monday reaching 2200m.

Snowpack Summary

40cm of new snow in the past 24 hours. Expect significant loading on lee slopes from strong southerly winds overnight. The Jan 15 surface hoar is buried 80-100cm and recent snowpack stability tests indicate it is likely to be triggered and propagate. The Dec 17 surface hoar/ crust complex is down 130-180cm.

Avalanche Summary

We are currently experiencing a widespread natural avalanche cycle from 40cm of new snow in the past 24 hours and strong southerly winds. Numerous natural avalanches up to size 3 were observed in the highway corridor during the overnight period. Avalanches are likely propagating on the January 15 surface hoar down layer down 80-100cm.

Confidence

Freezing levels are uncertain

Problems

Storm Slabs

40cm of new snow and strong southerly winds in have created a reactive storm slab. Expect storm slabs to be significantly thicker on lee features where snow has been transported by wind. This layer is easily triggered and will need time to stabilize.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

2 - 3

Persistent Slabs

Although this surface hoar layer is now buried 70-100cm deep, it will be easily triggered today with addition of the new snow load. Stability tests show that this layer has good propagation potential, making large avalanches likely.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3

Deep Persistent Slabs

A surface hoar layer, down 1-1.5m, that was buried in mid December continues to be reactive. Avalanche control had a few avalanches stepping down to this layer, even in areas where it had been previously controlled. The new load may wake it up again.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 4

Valid until: Jan 25th, 2015 8:00AM