Bollettino valanghe

Yukon

Dec 31, 2021 – Jan 1, 2022Avalanche Canada
Vedi sulla mappa
Archiviato · scaduto 5 years ago

Pericolo valanghe

Sun
Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
Senza grado
Apri la mappa completa

In sintesi

Shifting wind (again) means reverse and cross-loading developing. Back off slopes if you see 30 cm or more of recently wind-loaded snow. Variable snowpack conditions exist throughout the region. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    1–2

    Recent shifting winds have created pockets of wind slabs on most exposed slopes, especially at treeline where the fetch is greater. These aren't likely not 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 can be surprisingly large in size and distribution due to the greatest amount of recent snow.

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    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 - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack. Recent weather patterns have resulted in a high degree of snowpack variability within the region.

Weather Forecast

An arctic ridge of high pressure will re-establish briefly, leading to another clear and cold day heading into Friday. As a strong system will quickly intensify over the Gulf of Alaska, very strong winds will develop ahead of the front. Moderate snowfalls amounts are expected for the weekend.

THURSDAY NIGHT: Clear / Moderate northwest winds in the alpine / High of -18

FRIDAY: Flurries all day / Strong southwest winds in the alpine / High of -14

SATURDAY: Snow ~10-15 cm / Strong southwest easing off during the day / High of -12

SUNDAY: Snow ~ 10 cm / Moderate north winds / High of -25

Avalanche Summary

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

If you are out in the mountains, please consider filling out a Mountain Information Network report.

Snowpack Summary

On Wednesday, the region received about 5 and 15 cm of new snow, with favoured amounts in the Wheaton area. Switching winds (southerly then northerly) have redistributed the new snow which now covers old surfaces such as sastrugi, old wind slabs or recently 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 surface 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.

Regioni coperte