Avalanche forecast

South Rockies

Nov 28 – 29, 2012Avalanche Canada
View on map
Archived · expired 14 years ago

Avalanche danger

Fri
Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
Open full map

Highlights

If the storm arrives ahead of schedule on Wednesday, danger will quickly rise to Thursdays forecast values.  This bulletin is based on a very small amount of data, significant variations in conditions exist.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3
    Windslabs are likely getting less sensitive by the day, but you should still be suspect of steep wind loaded features at and above treeline.  A whole new round of storm slabs will likely come into play Friday as the storm crosses the region.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–4
    A stout rain crust from early November is found near the base of the snowpack.  Around a meter of snow rests on this crust.  It's getting hard to trigger, but I suspect you could still activate it in areas where the 'pack is thin and/or rocky.

Confidence

Fair - Due to limited field observations

Weather Forecast

A massive low pressure system in the gulf of alaska is driving a moist & active weather pattern that will persist through the weekend.  The majority of the system gets eaten up on the coast, but the South Rockies region will still see a good shot of snow.  I expect the first pulse to produce 5 cm Thursday night.  Look for light snowfall Friday to produce another 5 - 10 cm before tapering off Friday night.  Another pulse enters South Rockies airspace Saturday morning which should produce another 5 - 10 cm.  I expect 15 - 30 of total storm snow to be in place by Sunday morning.  Freezing levels should stay around 1200m all weekend.  Strong to Extreme alpine winds ramp up Thursday morning and should persist through the weekend. 

Avalanche Summary

No recent avalanche observations.

Snowpack Summary

Surface conditions vary throughout the region.  You might find surface hoar, a light zipper crust or something entirely different depending on what drainage you're in.  You need to know what the weekends snow is falling on before committing to a line.  Start by going small this weekend & remember that the storm slab has the potential to behave in very different manors depending on what aspect & drainage you're in.  This is a very young snowpack, don't take your eyes off it.  Alpine snow depths are somewhere between 1 - 2 m.  Depths quickly drop below threshold near treeline.  An early season rain crust exists from rain events in late Oct./early Nov.  Wind exposed terrain at and above treeline features old isolated wind slabs that range from 50 - 100 cm in depth. 

Regions covered