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 17th, 2018–Feb 18th, 2018

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

Regions

Purcells.

Fresh wind slabs and cornices have formed at higher elevations. Riding preserved powder in sheltered trees is a good option for the weekend.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

The very south of the region may see lingering flurries on Sunday; otherwise, we're looking at clear and cold from Sunday onwards, with overnight lows near -25 Celsius in some locations. Sunday: Mostly cloudy but cold. Isolated flurries in the south. Tree line temperatures around -15 Celsius. Winds light to moderate northeasterly.Monday: Sunny with cloudy periods. Tree line temperature around -14 Celsius. Winds light northerly.Tuesday: Cloudy with sunny periods. Tree line temperature around -13 Celsius. Light winds becoming moderate northerly. 

Avalanche Summary

On Friday, skiers were able to intentionally trigger small (size 1) wind slab avalanches in immediate down wind (lee) features near ridge crests. See here for an update on conditions near Golden. On Wednesday, a few small avalanches, including one involving a skier, were reported in recent storm snow with crowns approximately 30 cm deep.A week ago, explosive control work continued to produce large, deep avalanches up to size 3 on north to southeast aspects above 2200m. On the same day, a skier is believed to have remotely (from a distance) triggered a size 1.5 avalanche on a northwest aspect at 2800m that failed on the early January layer.Although deeper, persistent avalanche activity is becoming less frequent, these avalanches point to the continued reactivity and destructive potential of these layers.

Snowpack Summary

Recent storm snow totals are 10-20cm with more in the very south of the region: Dial back your terrain use if you are seeing more than 25 cm of new snow in your location. Moderate south west through north west winds shifted these accumulations into deeper, reactive slabs in wind-exposed terrain. The recent snow sits on a mix of older wind slabs in exposed higher elevation terrain, a sun crust on steep solar aspects and surface hoar on sheltered slopes.Below the snow surface several persistent weak layers make up a troublesome snowpack which is not tolerating recent storm loads. In the top 1-2 m of the snowpack, two surface hoar/ crust layers buried in January can be found. Expect to find one or other of these on all aspects and elevations.Deeper in the snowpack (around 200 cm deep) is a facet/crust/surface hoar layer from December, most prevalent at and below tree line.Near the base of the snowpack is a crust/facet combo, most likely to be triggered from thin spots in the alpine.All of these layers have produced large avalanches recently. The wide distribution and ongoing reactivity of these layers suggests that avoidance through choosing simple terrain is the best strategy.

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.