Avalanche forecast

South Rockies

Feb 5 – 6, 2015Avalanche Canada
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Avalanche danger

Sat
Sun
Alpine
4 · High
Treeline
4 · High
Below
2 · Moderate
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Highlights

Avalanche danger is high due to loading from new snow or rain, and wind.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–4
    Snow or rain continues to accumulate making natural avalanches more likely to slide. Windslabs developing on northeast aspects at higher elevation and wet slabs/loose avalanches problems at all elevations are incorporated into this problem.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–5
    The load from the new snow and rain soaking the surface snow could lead to avalanches stepping down to the deeper weak layers.

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

The second pulse of warm and mild weather associated with the low pressure system off the coast is expected to spread moderate to heavy precipitation over the region tonight (10-15 mm) and through Friday (10-15 mm).  Freezing levels could reach up to 2000m during the night and lower back down to 1800m tomorrow. A third wave of moisture with similar characteristics as the one before will be drifting inland on Friday night bringing another 15 mm of precipitation during the night and through Saturday. Freezing levels are expected to be around 2000m. Sunday is still looking warm but somewhat dryer. Winds are forecast to be moderate to strong from the southwest for the whole period.

Avalanche Summary

Several skier and explosive triggered avalanches up to size 2 out of treeline and alpine start zones were reported. Sluffing and shooting cracks were also observed as a slab was developing in the afternoon.

Snowpack Summary

Around 10 mm of heavy snow, or rain below 1500m, has accumulated over 5 cm which is sitting on a variety of surfaces; on a surface hoar and crust combo (referred to as the “late January surface hoar/crust” further down) in more sheltered areas, on a thin breakable crust in more wind affected areas or over windslabs on northeast aspects in the alpine. Significantly more load  is expected to add on to the snowpack through the night and tomorrow (total 20-30 mm as rain up to around 2000m) driving the avalanche danger to rise and making travelling conditions very dangerous in the backcountry. The rain is expected to weaken the late January crust/surface hoar layer, therefore increasing the likelihood of avalanches stepping down to deeper weak layers. The mid-December crust/facet/surface hoar combo found down 50-95 cm and could come out of its dormant stage making for some very large avalanche potential .

Regions covered