Bulletin d’avalanche

North Rockies

Feb 14 – 16, 2021Avalanche Canada
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Archivé · expiré 6 years ago

Danger d’avalanche

Tue
Wed
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Points saillants

Human triggered avalanches remain possible, but time and cold temperatures have reduced their sensitivity to triggering. Watch for wind slabs in funny places in the alpine as east/southeast winds continue to blow. Read about managing these conditions in this forecaster blog.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    We've recently had wind from a variety of directions including but not limited to north and east. This has resulted in wind slabs that are spread across many terrain features and aspects. Cold temperatures and time are likely allowing these slabs to become old and tired. Watch for fresh wind slabs Sunday as strong southeast wind Saturday night may form new wind slabs where there is snow available for transport.  

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1.5–2.5

    A surface hoar layer buried near the end of January is now down 25 to 40 cm and was previously quite sensitive to human triggering. Cold temperatures, time, and the relatively shallow depth of the overlying slab have helped to reduce activity on this interface, but it's still there and human triggered avalanches remain possible. This interface seems to be deepest and most sensitive to human triggering in the McBride area. This layer has been the most sensitive right at treeline, but it may extend up into the alpine, and/or down into the trees in some locations.

Confidence

Moderate - Uncertainty is due to extremely variable snowpack conditions reported through the region. Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

While cold temperature are with us through the weekend it looks like things will warm up a bit next week.

SATURDAY NIGHT: Overnight low temperature around -28 C, strong southeast wind, no snow expected.

SUNDAY: Broken cloud cover, daytime high temperature around -12 C, moderate west/southwest wind, a few cm of snow possible.

MONDAY: Broken cloud cover, daytime high temperature around -5 C, light west/southwest wind, trace of snow possible.

TUESDAY: Broken cloud cover, daytime high temperature around -5 C, moderate to strong west/northwest wind, trace of snow possible.

Avalanche Summary

This older avalanche was spotted around Tete Juane, it likely ran before the cold snap. Other than that there have been no recent avalanche observations.

During the first week of February there were small human triggered avalanches around Pine Pass and other observations that suggest the late January surface hoar isn't going to go away anytime soon. There are some great visuals of that activity in this MIN. 

Snowpack Summary

There is about 25-40 cm of snow resting on buried surface hoar which is most prevalent above 1600 m. It likely reaches into the alpine too, we're just not sure how high it extends. It may be present down in the trees in some places as well. This surface hoar seems to be deepest, and most sensitive to triggering around the McBride area. 

Below 1600 m this snow sits on a crust. 

There are presently no deeper concerns in the snowpack.

Terrain and Travel

  • Be careful as you transition into wind affected terrain.
  • Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.
  • Carefully evaluate big/extreme terrain features before committing to them, it's not full "go" time yet.

Régions couvertes