Avalanche Forecast

Archived

Jan 14th, 2012–Jan 15th, 2012

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Northwest Inland.

Confidence

Fair - Due to limited field observations

Weather Forecast

Sunday should be a beautiful day in the mountains as an outbreak of cold, dry Arctic Air takes hold of the region. Expect alpine winds out of the N, NE with lower elevation winds out of the E. Temperatures dip down to -26 overnight with a daytime high around -10. This pattern looks to persist through Tuesday evening.

Avalanche Summary

There have been no avalanches observations reported from the region.

Snowpack Summary

There is about 235 cm at 1500 metres.Heavy rain occurred last weekend up to about 1000 metres. Cooling since the storm has created a rain crust up to about 1200 metres. Above that, high winds redistributed the storm snow into wind slabs on lee and cross-loaded features. Since then, the region has received only dribs and drabs of new snow, and I suspect that last weekend's wind slab has gained considerable strength. I would expect soft slabs developing at treeline and in the alpine from the light accumulations throughout the week.There is an old rain crust that is buried down about a metre that is knife hard and showing old facets above and below. The snowpack is well settled below the rain crust down to the ground. The snowpack in the alpine is highly variable.Strong winds with almost every storm this winter have scoured ridges and knolls down to bare ground, and exposed boulders on some slopes.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.