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Archived

Avalanche Forecast

Feb 20th, 2021–Feb 21st, 2021
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
5: Extreme
The avalanche danger rating in the alpine will be extreme
Treeline
5: Extreme
The avalanche danger rating at treeline will be extreme
Below Treeline
5: Extreme
The avalanche danger rating below treeline will be extreme

Regions: Glacier.

New snow will not bond well to the complex drought interface of old facetted surfaces and previous windslabs.

Hazard levels will continue to increase as the storm intensifies through the weekend; peaking Sunday night into Monday morning.

Weather Forecast

A westerly flow is over BC, bringing a series of fronts Saturday night through Monday.

Today: Cloudy with flurries (5cm). Alpine High -10 C. Ridge wind strong W.

Tonight: Flurries (5 cm). Low -11 C. Strong SW wind.

Sunday: Snow (20-30cm). High -5 C. Extreme SW wind. Freezing level (FZL) 1300m.

Monday: Snow (15-20cm). Extreme W wind. FZL 1300m.

Snowpack Summary

Up to 15cm of snow overnight, brings the total to 20-40cm over the Feb. 14th drought interface; this is predominantly a wind crust in exposed areas near the height of the pass, and buried windslabs and facets as you move East and West. Facets, and a waek suncrust still linger down ~70cm at the Jan. 24th PWL. The mid and lower snowpack are strong.

Avalanche Summary

Field teams observed small avalanches recently in the Illecillewaet (size 1.5 windslab low in the Dogleg) and Flat creek (size 1.0 dry loose from a NW aspect in the alpine).

There has been more snowfall just to our West, and avalanche activity in this area has increased in the past 24hrs - likely a sign of things to come in our region.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Avalanche Problems

Storm Slabs

40cm and counting is being redistributed by moderate SW wind. This lies over the Valentine's Day weak interface of facets and variable wind effect. Check out this MCR describing the buried windslabs in more detail.

  • The recent snow is now hiding windslabs that were easily visible before the snow fell.
  • Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Loose Dry

Expect the new snow to be easily triggered in steep terrain.  Loose snow avalanches will gain mass quickly where the new snow sits on previously faceted and unconsolidated snow.

  • Use caution above cliffs and terrain traps where small avalanches may have severe consequences.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 2

Persistent Slabs

The Jan 24th interface has been found in numerous recent profiles. This layer is most concerning on steep, unsupported terrain features on solar aspects

  • Persistent slabs may be more sensitive to human triggering on solar asp where it sits on sun crust

Aspects: South East, South, South West, West.

Elevations: All elevations.

Likelihood: Unlikely

Expected Size: 2 - 3