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 12th, 2019–Feb 13th, 2019

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
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 Rockies.

Our new snow won't form a strong bond with the surface over the short term. Expect widespread instability in the new snow, with danger increasing as it forms storm slabs under the effect of wind and with settlement.

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Tuesday night: Cloudy with continuing flurries bringing about 10 cm of new snow. Light to moderate southwest winds.Wednesday: A mix of sun and cloud with easing isolated flurries and a trace of new snow, with new snow totals around 30 cm. Light west winds. Alpine high temperatures around -12.Thursday: Sunny with increasing cloud and flurries beginning in the evening. Light southeast winds. Alpine high temperatures around -10.Friday: Cloudy with continuing scattered flurries and a trace to 5 cm of new snow, with new snow totals of 5-10 cm. Light west winds. Alpine high temperatures around -9.

Avalanche Summary

Preliminary reports from Tuesday showed numerous loose dry and storm slab avalanches releasing within the height of new snow, upwards of 20 cm deep. These occurred naturally as well as with ski cutting and skier traffic. Expect a continuation of this type of activity on Wednesday.A report from the Flathead on Monday described continued observations of large whumpfs at 1700-1800 metres. This can be attributed to collapsing of the large, weak, January 17 layer of surface hoar. Collapses of this type on a sufficiently large and steep slope can be expected to produce persistent slab releases.A social media post from the Marten area of Elk Valley on Thursday described touchy persistent slab conditions, with lots of smaller slabs releasing over the mid-January surface hoar layer. Check out the post here. Of note is the fact that this area was previously untracked, leaving the mid-January layer undisturbed.

Snowpack Summary

Up to 30 cm of new snow has buried a variable surface of heavily wind affected old storm snow at alpine and wind-exposed treeline elevations, while adding to 25-35 cm of lower density storm snow from last week in sheltered areas above 1700 metres. In these sheltered areas, this older storm snow may cover a layer of weak, feathery surface hoar crystals. Below 1700 metres, the new snow buried a thinner cover (5-10 cm) of the same storm snow that instead overlies a melt-freeze crust.The mid-January layer of surface hoar or a crust is now buried around 55 to 65 cm deep. The surface hoar is found on shaded and sheltered slopes and is most prominent between 1600 m and 1900 m but has been found up to 2200 m. The melt-freeze crust is found on south aspects at all elevations. This layer was the subject of a recent Special Public Avalanche Warning.The middle of the snowpack is generally consolidated. The bottom half of the snowpack is unconsolidated and composed of weak and sugary faceted grains. The basal snowpack is becoming even weaker under prolonged cold temperatures, especially in thin snowpack areas.

Problems

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.

Loose Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.

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.