Avalanche Forecast

Issued: Feb 13th, 2021 3:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs.

Avalanche Canada jcoulter, Avalanche Canada

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Wind slabs sitting on cold, sugary faceted surfaces may take longer to bond than we are used to. There may be potential for wide propagation on bigger terrain features.

Summary

Confidence

Moderate -

Weather Forecast

SATURDAY NIGHT - Partly cloudy, trace of new snow, moderate to strong south west wind, low -16

SUNDAY - Overcast, 2-5 cm of snow, moderate south west wind / high near -14

MONDAY - Cloudy, 2-5 cm of snow, light south west wind / highs of -10

TUESDAY - Cloudy, trace amounts of snow, moderate to strong north west wind, highs of -7

Avalanche Summary

In the Babine area a field team noted numerous size 1-2 wind slabs in the alpine from the past 36 hours. This is in keeping with other avalanche observations from the outflow winds like this size 2 near Miller Creek.

Wind slabs have also been reactive to human triggering in wind loaded and cross loaded features. Most ski cut results have been in the size 1 to 1.5 range, but bigger terrain features could produce larger propagation and bigger avalanches! 

In the south west part of the region, a natural size 3 cornice triggered avalanche was reported, although the date was uncertain.

Check out this forecaster MIN post from Microwave from Thursday to see the widespread wind effects. 

A Feb 9th MIN observation shows some stiff wind affected snow over sugary facets.

Evidence of recent natural wind slab avalanches (likely occurring Saturday) were observed on Sunday as discussed in this MIN report. Small loose dry avalanches were also reported, in some cases likely triggered by the sun.

Snowpack Summary

Hard slabs, scoured slopes and sastrugi will be present where outflow effects have been the strongest. In more sheltered zones, reactive wind slabs will be found on a variety of aspects and elevations due to terrain effects and the variable wind directions.

In more sheltered areas, the cold temperatures are encouraging surface faceting. The late January interface is down 30-50 cm, consisting of isolated surface hoar in sheltered locations, and previous wind effect in exposed areas. On solar aspects, a buried sun crust can be found below 1000 m. 

The lower snowpack has two decomposing crust layers. The upper crust is 70-140 cm deep and continues to show occasional hard, sudden results in snow pits. The deeper crust at the bottom of the snowpack is more prevalent in shallow snowpack ranges. These deep persistent layers seem to be dormant under the current conditions, but shallow rocky slopes should still be carefully assessed and approached with caution. 

Terrain and Travel

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be aware of the potential for wide propagation.

Problems

Wind Slabs

An icon showing Wind Slabs

Steep, lee, westerly aspects have been the most reactive during the strong outflow winds. With winds shifting again to westerlies, expect reactive wind slabs on multiple aspects and elevations. Wind slabs will be especially susceptible to human triggering where stiff and punchy feeling snow sits on top of weak faceted crystals. Note that in some places avalanche hazard may be elevated where winds have penetrated into open pockets of terrain even at lower elevations.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Valid until: Feb 14th, 2021 4:00PM