Archived

Avalanche Forecast

Feb 17th, 2015–Feb 18th, 2015

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Kootenay Boundary.

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Confidence

Good

Weather Forecast

Sunny and dry for Wednesday with some cloud cover expected for Thursday and Friday. Above freezing alpine temperatures are expected on Wednesday; however, freezing levels should drop back down to 1600 mÂ for Thursday and Friday, and valley bottoms overnight throughout the forecast period. Generally light northwesterly winds are expected with a brief shift to southwesterlies as the clouds roll in on Wednesday afternoon.

Avalanche Summary

No new avalanches were reported on Monday or Tuesday morning.

Snowpack Summary

The surface snow is undergoing a melt-freeze cycle with a strong frozen state in the morning followed by a weak melted state in the afternoon, especially on sun-exposed slopes. Not only does surface snow become weak with daytime warming, but slabs lose stiffness making deeper weaknesses more susceptible to triggering. The crust buried at the beginning of February is down around 40-60 cm and generally well-bonded; however, this bond is much weaker where surface hoar overlies the crust. Below that, recent snowpack tests gave moderate to hard but sudden collapse results on the mid-January surface hoar where it was found down 113 cm on a northwest facing alpine slope, as well as moderate sudden planar results where it was found down 55-85 cm at treeline. The mid-December crust/facet/surface hoar weakness may be persisting in the mid to lower snowpack at higher elevations.

Avalanche Problems

Loose Wet

Surface snow could loose cohesion and sluff easily on steep sun-exposed slopes in the afternoon. Although small, these wet avalanches could have enough mass to knock you off your feet and take you for a ride.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Persistent Slabs

Although unlikely, these highly destructive avalanches remain possible with heavy impacts (e.g. cornice falls and surface avalanche stepping down) in the right spot (e.g. thin rocky areas). Daytime warming will also increase sensitivity.

If your sled is bogging down, don?t spin the track and trigger the weak layer below.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Unlikely

Expected Size: 1 - 5

Cornices

Not only a hazards in themselves, cornice falls can also act as heavy triggers for persistent slab avalanches on the the slope below.

Give cornices a wide berth when travelling on or below ridges.>Cornices become weak with daytime heating. >

Aspects: North, North East, East, South East.

Elevations: Alpine.

Likelihood: Unlikely - Possible

Expected Size: 1 - 3