Avalanche Forecast

Archived

Dec 17th, 2011–Dec 18th, 2011

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

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.

Regions

South Columbia.

For more information on the effects of incremental loading, please check out our forecasters blog by clicking the tab at the bottom of the forecast page.

Confidence

Fair - Forecast snowfall amounts are uncertain on Sunday

Weather Forecast

A cold front is expected to move through the interior on Saturday night. This trailing cold front will follow in the wake of the warm air that we saw on Saturday and is forecast to bring another 10 cm by Sunday morning to the North and West regions of the Monashees and Cariboos. Less snow is forecast for the South and East areas of the Selkirks and Purcells. Freezing levels are expected to fall back to valley bottoms as cold air and moderate to strong Northwest winds move over the interior. Sunday is expected to be mostly dry but probably still overcast. Clearer and colder weather should be across the interior on Monday. The next Pacific system is expected to start moving in from the coast on Tuesday. It is a little early to determine intensity and timing for the next system.

Avalanche Summary

Loose snow sluffing in steep terrain up to size 2.0 has been reported in the region.

Snowpack Summary

A cold front is expected to move through the interior on Saturday night. This trailing cold front will follow in the wake of the warm air that we saw on Saturday and is forecast to bring another 10 cm by Sunday morning to the North and West regions of the Monashees and Cariboos. Less snow is forecast for the South and East areas of the Selkirks and Purcells. Freezing levels are expected to fall back to valley bottoms as cold air and moderate to strong Northwest winds move over the interior. Sunday is expected to be mostly dry but probably still overcast. Clearer and colder weather should be across the interior on Monday. The next Pacific system is expected to start moving in from the coast on Tuesday. It is a little early to determine intensity and timing for the next system.

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.

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.