Avalanche forecast

South Columbia

Dec 16 – 17, 2013Avalanche Canada
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Avalanche danger

Wed
Thu
Alpine
4 · High
Treeline
3 · Considerable
Below
2 · Moderate

Highlights

Forecast snowfall amounts could vary across the region. Southern and western parts of the region could see considerably less snow, potentially resulting in lower avalanche danger. Be sure to make careful local observations. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–4
    Forecast new snow and strong to extreme westerly winds will likely create dense new wind slabs in exposed lee terrain at all elevations. These wind slabs may release naturally in specific areas.
  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–5
    Continued loading and mild temperatures could make buried persistent weaknesses in the upper and mid snowpack much more reactive. Make conservative terrain choices over the next couple days.

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Tonight and Tuesday: A warm front moves through tonight bringing generally light precipitation, followed by the trailing cold front on Tuesday with stronger precipitation. Expect accumulations of up to 20 cm in some areas. The freezing level is around 900-1100 m and winds are strong to extreme from the SW-W.Wednesday: Precipitation should taper off with gradual clearing throughout the day. Temperatures drop with the freezing level returning to valley bottom by evening. Winds ease to light or moderate from the NW. Thursday: Mainly sunny and cooler. The freezing level should be at valley bottom with moderate northerly winds.

Avalanche Summary

Parts of the region reported a fairly large natural avalanche cycle late Saturday through Sunday morning, with several avalanches up to Size 3. Skier testing also produced a few avalanches up to Size 2, primarily in wind loaded terrain or on very steep convex rolls.

Snowpack Summary

Although recent accumulations have been highly variable, up to 60cm of snow now overlies the weak faceted crystals or small surface hoar which formed during the last cold snap. Rising temperatures are reported to have enhanced slab properties creating a more reactive "upside-down" snowpack, especially at lower elevations. Moderate to strong southwest winds have created dense wind slabs in exposed high elevation terrain.As of late there has been no reported activity on the late-November interface which consists of sun crusts on steep south facing slopes and surface hoar in sheltered areas. This layer, buried between 60-80cm below the surface, is generally considered to be "stubborn" to trigger; however, avalanches at this interface could have nasty consequences.

Regions covered