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Avalanche Forecast

Archived

Feb 14th, 2022–Feb 15th, 2022

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

Regions

Lizard-Flathead.

Don't rely on surface conditions for clues to where the tricky persistent problem still exists. Open slopes at treeline are the most concerning, where buried surface hoar may be preserved. 

Whumpfing, shooting cracks and recent avalanches are clear signs of an unstable snowpack. 

Confidence

Moderate - Forecast snowfall amounts are uncertain. Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

The cold front moves out of the region tonight, light flurries continue Tuesday. A high pressure builds Wednesday, bringing mostly dry conditions and scattered cloud.

MONDAY NIGHT: Cloudy with light snowfall delivering 5 cm by morning. A chance of enhanced precipitation around Fernie. Light westerly winds. Freezing levels around 1000m. 

TUESDAY: Mostly cloudy with light westerly winds. Chance of flurries. Freezing levels reach 1200m. Alpine high of -3. Tuesday night will see light accumulation overnight, 2-8 cm. 

WEDNESDAY: A mix of sun and cloud with light westerly winds. Freezing levels reach 1300m, alpine high of -2. 

THURSDAY: Increasing cloudy with strong westerly winds. Chance of flurries. Freezing levels rise rise toward 2000 m. Alpine high of 0. 

Avalanche Summary

A large persistent slab avalanche was reported in the Steeples on Saturday afternoon, on a south facing aspect at 2300 m. This avalanche had wide propagation and ran 2 km in length and is believed to have occurred on the late January persistent weak layer, crowns were estimated at 50 cm deep. 

Several natural and human triggered wind slab avalanches to size 2 have been reported as recently as Saturday, on north through east facing slopes. 

Snowpack Summary

Light snowfall will overly dense wind effected surfaces in exposed terrain at treeline and alpine elevations. In sheltered areas and lower elevations, new snow will fall on a widespread melt freeze crust. 

The late January interface is buried 15-40cm deep, and consists of a melt-freeze crust at lower elevations and on solar aspects extending into the alpine. Surface hoar sits above the crust in sheltered areas at treeline and below. 

The widespread January 18 rain crust is now around 40-100cm deep with weak faceted snow above. It is most prominent in the Lizard range. In heavily wind scoured areas at treeline and above this crust may even be found on the surface. 

The snowpack below is well consolidated, with the early-December crust/facet persistent weak layer buried 100-200 cm deep. It is currently considered dormant. We expect this layer to become active later this season, check out the forecaster blog for more information.

Terrain and Travel

  • Avalanche hazard may have improved, but be mindful that deep instabilities are still present.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
  • Be careful as you transition into wind affected terrain.

Problems

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.

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.