Lawinenlagebericht

Yukon

Jan 1 – 2, 2022Avalanche Canada
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Lawinengefahr

Mon
Tue
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
Keine Stufe
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Kernpunkte

Choose mellow slopes out of the wind to find the best riding and the lowest avalanche hazard. New snow and south winds are likely building reactive windslabs. Constantly assess local conditions, recent snowfall amounts have varied across the region.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    New snow and recent shifting winds have created pockets of wind slab on most exposed slopes, especially at treeline where there is more snow available for transport. 

    New wind slabs aren't likely to bond very well to the old hard slab and faceted surfaces below. Sensitivity to triggering will be greatest near ridge crests. 

    In areas inland, wind slabs could be surprisingly large due to Wednesday's deeper localized snowfall.

  • Deep Persistent Slabs

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

    Although the crust associated with this layer has largely decomposed, the weak sugary crystals at the base of the snowpack remain. The bridging affect of the wind hammered upper snowpack is making it harder to trigger this layer but now is not the time to become complacent. When managing hard slab on top of facets, try to think in terms of consequences just in case of a surprise. "If I trigger an avalanche here, what are the consequences? Will the avalanche be large? Are there terrain traps?" 

Confidence

Moderate - Forecast snowfall amounts are uncertain. Recent weather patterns have resulted in a high degree of snowpack variability within the region.

Weather Forecast

FRIDAY NIGHT: Mostly cloudy. 5-15 cm of snow expected. Strong south winds trending to extreme southwest at higher elevations. Temperature at 1500 m around -13 C.

SATURDAY: Mostly cloudy. 5-10 cm of snow expected. Light Southwest winds, with a switch to northerly outflow winds at lower elevations in the evening. Temperature at 1500 m dropping to around -15 C.

SUNDAY: A mix of sun and cloud. Around 5 cm of snow expected overnight, with another 0-2 cm through the day. Strong northeast winds, trending to southeast at higher elevations. Temperature at 1500 m between -20 C and -25 C with a possible temperature inversion. 

MONDAY: A mix of sun and cloud. Possible trace of snow expected. Strong northeast winds trending to southeast at higher elevations. Temperature at 1500 m below -25 C, with a possible temperature inversion.

Avalanche Summary

Several wind slabs avalanches (size 1) reaching the highway were reported on Wednesday afternoon. 

If you are out in the mountains, and have information to, or even just good vibes and good photos to share, please consider making a quick post on the Mountain Information Network.

Snowpack Summary

By Saturday morning, we expect to see 10-25 cm of new snow in a 24 hour period. The forecasted strong southerly wind is likely building reactive windslabs in leeward terrain.

Here and here are two great Mountain Information Network (MIN) posts about conditions on Thursday in the White Pass area.

On Wednesday, the region received about 5 to 15 cm of new snow, with the higher amounts being in the Wheaton area. Switching winds (southerly then northerly) redistributed this snow over old surfaces such as sastrugi, wind slabs or scoured slopes in the alpine. 

At treeline, the wind also affected the surface, but pockets of powder can be found between cross-loaded features. Underneath this wind-affected snow, there is a thick layer of weak snow (faceted grains).

The lower snowpack is made up of weak sugary snow. An avalanche at this interface is most likely to be triggered in shallow areas or with a large impact like a cornice fall or a larger wind slab avalanche.

Terrain and Travel

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Keep your guard up at lower elevations. Wind slab formation has been extensive.
  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

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