Avalanche forecast

South Columbia

Mar 21 – 22, 2013Avalanche Canada
View on map
Archived · expired 14 years ago

Avalanche danger

Sat
Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
Open full map

Highlights

Periods of strong solar radiation may weaken and release storm slabs on Southerly aspects where a buried crust may act as a good sliding surface. Cornices may also fall off due to solar warming.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–6
    The March 10th weak layer of surface hoar is buried down more than a metre in most places. Large loads like cornice falls may trigger this deeply buried weak layer.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–4
    The new storm slab may take a couple of days to settle and bond to the old surface. Pockets of wind transported snow may continue to be easily triggered by light additional loads. New cornice growth may be extensive and weak.

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Friday

Weather Forecast

Overnight and Friday: Unsettled convective weather is forecast to bring a few more cms of snow overnight and during the day. Amounts may be slightly enhanced in some of the up-slope areas. Alpine temperatures should drop to -14.0 overnight and the freezing level is expected to rise to about 900 metres during the day. Moderate Northwest winds should become light Northerly with moderate gusts. Saturday: A ridge of High pressure is slowly moving into the interior regions from the coast. Cloudy conditions in the morning should clear gradually during the day. There is a chance of a few flurries in the morning. Freezing levels are expected to rise to 1000 metres under clearing skies. Sunday: The ridge of High pressure is expected to continue to bring mostly clear skies and light Northerly winds to the interior ranges. Overnight alpine temperatures are forecast to be about -13.0 with the freezing level rising to 900 metres during the day. Periods of strong solar radiation are expected.

Avalanche Summary

Skiers controlled soft slab avalanches up to size 1.5 in the Monashees and Selkirks. Loose snow sluffing from steep terrain was also reported.

Snowpack Summary

There is quite a bit of variability with respect to the amounts of new snow over the last few days. The recent storm amounts are between 40-80 cms at higher elevations. Strong winds overnight and early Wednesday morning developed thick pockets of wind slab at higher elevations. Cooling temperatures have promoted bonding to the moist snowpack at lower elevations. New cornice growth is reported to be extensive and weak. Expect natural cornice falls that may trigger weak layers that are buried down a metre or more on slopes below. The new storm load may trigger the March 10th weak surface hoar layer.

Regions covered