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

Feb 4th, 2013–Feb 5th, 2013

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

Regions

South Columbia.

If your receive less then 20 cm of snow in your local riding area, consider the danger ratings to be a step to high on Tuesday.

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Tuesday: The trailing cold front has brought temperatures back down to seasonal norms. The next well developed system brings light-moderate snow amounts with localized heavy amounts to some SW facing slopes. Ridgetop winds will blow strong from the West and alpine temperatures will be near -8. Freezing levels will hover around 1200 m. Wednesday: Upper disturbances embedded in the SW flow will bring continued stormy conditions. Snow amounts 10-20 cm throughout the day, tapering off overnight. Ridgetop winds will continue to be strong from the West. Alpine temperatures near -9 and freezing levels around 1100 m. Thursday: Weak unsettled conditions will prevail with no significant precipitation. Ridgetop winds will blow light from the South. Alpine temperatures near -9 and freezing levels will stay near 1000 m in the afternoon then falling overnight.

Avalanche Summary

Wind slabs also continued to release naturally or were triggered by skiers up to size 2. Region wide, numerous reports of skier triggered slab avalanches up to size 2 were initiated. Most of these avalanches have failed on the January 23 persistent weak layers. These occurred anywhere from 1600 m-2200  m and on a variety of aspects. With forecast storm snow and wind transport these layers may become more reactive naturally under the new loads.

Snowpack Summary

Wind slabs continue to develop in the alpine and at treeline. Forecast storm snow will blanket a sun crust that has developed on steep Southerly aspects, and a melt-freeze crust has developed at lower elevations due to the recent high freezing levels. The recent storm slab continues to be reactive on solar aspects where an old sun crust has been buried and  at treeline and below on steep convex slopes that host preserved buried surface hoar at the January 23rd interface (between 40-80 cms down). The mid-pack is well settled and strong. There are a few locations that continue to find a well preserved surface hoar layer from early January that is buried down about 90-100 cms and has been less reactive.

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.