Avalanche forecast

Purcells

Feb 27 – 28, 2014Avalanche Canada
View on map
Archived · expired 13 years ago

Avalanche danger

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

Highlights

Although the frequency of natural avalanches has gone down recently, the possibility of triggering a large, destructive avalanche is still very real. See the Forecasters Blog for more insight into this tricky situation.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    Wind slab development may now switch to south and south west slopes as the incoming arctic air drives down from the north east. This may build cornices in places not usually seen.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    2–5
    A dense storm slab from the last series of storms now lies above a touchy, persistent weak layer. This slab has shown a propensity for remote triggering and propagating over wide distances. In wind-loaded areas the slab may be up to 1.5 metres thick.

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

The ridge of high pressure continues to dictate conditions for the forecast period. Cold, dry arctic air scheduled to move back into the region. Strong arctic outflow winds have already begun and will continue into the coming weekend. For a more in-depth look at the weather, check out the latest: Weather OutlookThursday night: Cloudy periods, freezing level at valley bottom, trace of precipitation,...ridge top winds, light to 25Km/h.Friday: Sunny, freezing level at valley bottom, trace of precipitation in the forecast, ridge top winds from the north to 20 Km/h.Saturday: Sunny, freezing level at valley bottom, ridge top winds from the north gusting to 40 Km/h.Sunday: Sunny, freezing level at valley bottom, trace of precipitation, ridge top winds light.

Avalanche Summary

Natural avalanches are still occurring up to size 2.5 in the forecast area, and as temperatures warm up may increase in frequency. Cornices failures may also occur with the warming temperatures and will certainly add to the hazard.Conditions are ideal for rider triggering right now. We have received numerous reports of skier triggered and skier accidental avalanches, many of which have released quite deep in the snowpack. Neighboring areas have reported avalanches that were remotely triggered from a considerable distance.

Snowpack Summary

The storm slab of about 1 metre overlies a persistent weak layer, (surface hoar/facet/crust combo) that was formed during the preceding month of cold dry weather. The storm slab appears to be gaining strength with settlement and warm temperatures but the persistent weak layer beneath it remains widespread at all elevations and aspects. Although this weak layer is not as reactive as it has been, it's still a very real concern. Surface hoar and near surface facetting is occurring on protected/shaded aspects, and solar aspects are moist to quite high elevations during the day with sun crusts forming at night. Winds shifting from south west to north east will signal wind slab development on south east slopes when the arctic outflow arrives from the northeast.Large settlements and whumpfs are still being reported indicating the ability of this weak layer to fail. Remotely triggered avalanches tell us it has the ability to propagate over large distances. Touchy conditions will remain for the near future.

Regions covered