Avalanche Forecast

Issued: Feb 16th, 2015 8:01AM

The alpine rating is moderate, the treeline rating is low, and the below treeline rating is low. Known problems include Loose Wet, Persistent Slabs and Cornices.

ccampbell, Avalanche Canada

Kootenay Boundary.

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Summary

Confidence

Good

Weather Forecast

Sunny and dry for Tuesday and Wednesday with some cloud cover expected for Thursday. Freezing levels around 1600 m for Tuesday before possible above freezing alpine temperatures on Wednesday; however, cooler temperatures expected again for Thursday, and freezing levels expected to drop to 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

Reports from Sunday are limited to small wet loose snow activity on steep sun-exposed slopes.

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 70-80 cm on a northeast facing treeline slope. This persistent weakness is generally down a metre or more. The mid-December crust/facet/surface hoar weakness may be persisting in the mid to lower snowpack at higher elevations.

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

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

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.

Be aware of thin areas that may propogate to deeper instabilites.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>If your sled is bogging down, don’t spin the track and trigger the weak layer below.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

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.

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

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Feb 17th, 2015 2:00PM