Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Jan 5th, 2012–Jan 6th, 2012

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
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 possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

South Columbia.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain on Sunday

Weather Forecast

The next couple days brings cooler temperatures and dryer conditions. Friday: Snow amounts up to 5cms in the morning. Mix of sun and cloud in the afternoon. Ridgetop winds 20-30km/hr from the SW. Alpine temperatures near -6, and treeline temperatures near -4. Freezing levels at valley bottom. Saturday: A Northerly flow brings mainly sunny skies with seasonal conditions. Ridgetop winds 15-20km/hr from the NW. Treeline temperatures near -9. Sunday: Light to moderate precipitation is expected accompanied by strong SW winds. Freezing levels may rise to 2000m by the afternoon.

Avalanche Summary

Thursday morning a large natural cycle was reported in the Rogers Pass area. These were large avalanches up to size 3.5 running to the end of run out zones and into creeks. Outside of the Rogers Pass area several natural avalanches occurred around 2400m on S-W aspects. Also to note a natural cornice release triggered a size 2 slab on the slope below. The mid-December persistent weak layer is buried down 80-120cms and is still a layer of concern. Avalanches that are failing on this layer are large-very large (sz 2-3.5). As the natural activity has somewhat tapered off, the sensitivity to skier, or sledder triggers are likely.

Snowpack Summary

New snow up to 20cms has fallen over the region. This blankets treeline and alpine elevations and buries a new surface hoar layer (up to 10mm in size) that formed over the New Year. Wind slabs are widespread and found in exposed alpine and treeline locations. With warmer temperatures the new snow has set up into a slab that overlies the surface hoar and old wind slabs. We can expect a rain crust up to 1700m due to Wednesday's precipitation and high freezing levels. Below the surface 80-120cms lurks a surface hoar/facet/crust interface (persistent weak layer) from mid-December. Testing on this layer has shown moderate to hard results with sudden planer characteristics. This weak layer has been very reactive; producing large, destructive avalanches. It still remains a layer of concern and should continue to be on your radar. Below this layer sits a strong mid pack.

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.