Lawinenlagebericht

Lizard-Flathead

Mar 6 – 7, 2022Avalanche Canada
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Lawinengefahr

Tue
Wed
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

Use extra caution on sunny slopes, and continually assess the snowpack for signs of instability as you change elevation and aspect. Avalanche activity is tapering off after a stormy period, but the snowpack still needs time to adjust to the rapid changes in the last week.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely - Possible
    Größe
    2–3

    Smaller avalanches have the potential to step down to this deeper persistent layer in sheltered north-facing treed terrain.

    Persistent slab avalanches are still possible due to a layer of buried surface hoar that is likely down around 50-100 cm. This problem is tricky to pin down because of its spotty distribution (it isn't a problem everywhere). It has been most reactive recently in the Flathead with reports of rider triggering, whumpfing and cracking a week ago.

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1.5–2.5

    Though stability is improving, human triggering of storm slabs should remain on your radar.

    Test the bond of new snow on smaller terrain features with low consequences as you travel through various elevation bands and aspects.

    The first punch of sun after the storm could make storm slab avalanches more likely, use extra caution on slopes facing the sun. 

    Cornices have grown during the last system as well so give them a wide berth.

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely - Very Likely
    Größe
    1–1.5

    With clearer skies forecasted across the region for the weekend, watch for the recent, loose snow to become more reactive as the sun warms the surface. 

    The recent snow came with very little wind, and the sun is starting to pack a bigger punch at this time of year. Small natural and rider triggered loose snow avalanches are likely.

Weather Forecast

General cooling and clearing trend with cold northern air providing good refreezes overnight, but upslope flow will continue to bring spotty cloud cover and bits of snowfall through the forecast period.

Saturday Night: Scattered clouds. 0-2 cm of snow expected. Light east ridgetop wind, trending to northwest at higher elevations. Freezing level falling to valley bottom. Treeline low around -8 °C.

Sunday: Mostly sunny. No new snow expected. Light east ridgetop wind, trending to moderate north at higher elevations. Freezing level at valley bottom overnight, rising to 1400 m through the day. Treeline high around -5 °C.

Monday: Partly cloudy. 0-2 cm of snow expected. Light west ridgetop wind, trending to strong northwest at higher elevations. Freezing level at valley bottom overnight, rising to 1500 m through the day. 

Tuesday: Mostly cloudy. 5-10 cm of snow expected overnight, and a possible trace through the day. Freezing level stays at valley bottom. Alpine temperatures around -15 °C.

Confidence

Moderate - We have a good understanding of the snowpack structure and confidence in the weather forecast Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Avalanche Summary

On Saturday, near Fernie, avalanche control with explosives triggered several storm slab avalanches up to size 2.5 on northeast aspects in the alpine, and a few loose dry avalanches up to size 1.5 around treeline. 

On Friday, near Fernie, numerous natural, rider, and explosive triggered storm slab avalanches up to size 2.5 were reported. Also, Numerous loose wet avalanches up to size 1.5 were reported in steep terrain on all aspects below tree line.

On Thursday, there were reports of many small Loose Wet avalanches in steep terrain below tree line across the region.

 

Snowpack Summary

20-35 cm of new snow fell with light winds overnight on Thursday and into Friday morning. A melt freeze crust may be present underneath this new snow, on all aspects, and reported as high as 2100 m. Snow has generally been rain-soaked below 1600 m. Expect to find moist snow underneath the melt-freeze crust, especially at lower elevations.

50-100 cm of recent storm snow is settling on a variety of old surfaces buried in late February: sun crusts, freezing rain crusts, old wind-pressed snow or cold, weak snow crystals on shaded aspects.

Smaller avalanches may step down to old, persistent layers such as the surface hoar layer buried at the end of January. The distribution of this layer is spotty in nature but has produced avalanches and concerning snowpack test results in the past week, mostly in the Flathead. While it does not appear to be as widespread or reactive in the Lizard Range, it has been found in some locations. 

The lower snowpack is generally well consolidated, with a crust/facet layer from early December found near the ground. It is currently considered dormant but could become active later this season. 

Terrain and Travel

  • If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
  • Use small low consequence slopes to test the bond of the new snow.
  • Minimize exposure to sun-exposed slopes when the solar radiation is strong.
  • Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.
  • Avoid rock outcroppings, convexities, and anywhere the snowpack is thin and/or variable.

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