Avalanche forecast

South Columbia

Feb 24, 2018Avalanche Canada
View on map
Archived · expired 9 years ago

Avalanche danger

Sun
Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
Open full map

Highlights

New snow (possibly up to 20 cm by Sunday) and wind will continue to build slabs and cornices at upper elevations. Sloughing, and cracking around skis and sleds are signs that the new snow is bonding poorly to the old surface.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–2.5
    New snow and wind will add to wind slabs that exist in many areas in the alpine and in open areas at treeline. These slabs have been particularly reactive on southeast to southwest facing slopes where they overlie a buried crust.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–4
    Buried weak layers exist in the snowpack and may be reactive to large triggers such as a cornice or step-down from a wind slab release. Human triggering may also be possible from shallow or thin. rocky, unsupported terrain.

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

SATURDAY: Mix of sun and cloud, light flurries increasing overnight. Accumulation up to 5 cm. Ridge wind light, west. Temperature -8. Freezing level valley bottom.SUNDAY: Snow. Accumulation 10-15 cm. Ridge wind moderate to strong, southwest. Temperature -7. Freezing level 700 m.MONDAY: Mostly cloudy, light flurries. Accumulation up to 5 cm. Ridge wind light, west. Temperature -8. Freezing level 900 m.

Avalanche Summary

Thursday we received reports of large (size 2.5) natural and cornice triggered avalanches on north and east aspects above 2200 m. At least one of these avalanches failed on deep weak layer, with a crown depth of 200 cm. There was also a report of skier's remotely (from a distance) triggering a size 2.5 slab avalanche on a south aspect at 2300 m that is believed to have failed on the crust that was buried mid-February.Since Tuesday there have been numerous reports of skier triggered slab avalanches (size 1-1.5) on predominantly steep, east through south-facing features between 1900 -2500 m, that also failed on the mid-February crust..On Monday, several natural wind slab avalanches to size 3 were reported on a wide range of aspects above 2100m. Although deeper, persistent avalanche activity has become less frequent over the past week, light triggers in shallow rocky areas, as well as large triggers such as a cornice collapse or step down from a wind slab release, still have the potential to result in large destructive avalanches.

Snowpack Summary

A light dusting of new snow now covers 40-60 cm of storm snow from last week that has settled into a slab and been redistributed by previously strong winds into stiff wind slabs in wind-exposed terrain. These accumulations overlie an interface that was buried mid-February consisting of; a mix of older wind slabs in exposed higher elevation terrain, a sun crust on steep solar aspects, a rain crust below 1600m, and surface hoar on sheltered slopes.Within the mid and lower snowpack are several persistent weak layers that are slowly beginning to show signs of improving, but still remain suspect.In the top 150-200 cm of the snowpack, two surface hoar/ crust layers buried in January can be found. Expect to find one or the other of these on all aspects and elevations.Deeper in the snowpack (200-250 cm) is a facet/crust/surface hoar layer from December that is most prevalent at treeline and below.Near the base of the snowpack is a crust/facet combo from late November.

Regions covered