Bollettino valanghe

Yukon

Jan 10 – 12, 2021Avalanche Canada
Vedi sulla mappa
Archiviato · scaduto 6 years ago

Pericolo valanghe

Tue
Wed
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
Senza grado
Apri la mappa completa

In sintesi

Avoid ridge crest & rock outcroppings in the alpine where you're most likely to trigger hard slabs. Softer slabs at treeline may rest on buried surface hoar making them surprisingly touchy. More snow and wind is on the way which is expected to exacerbate the wind slab problem.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    1.5–2.5

    Wind slabs. They're now everywhere, and we expect them to remain problematic through the forecast period as more wind and snow come into the picture.

    Up high the wind slabs are fat and hard. In the alpine you need to be careful to avoid the spots where the slabs are thinner and thus easier to trigger. Ridge crest is one of those places where hard slabs are often triggered. Rock outcroppings are another problem area.

    At treeline the slabs are softer, but easier to trigger. At this elevation slabs may be resting on surface hoar which could make them quite sensitive to human triggering. Problem areas at treeline include convexities and terrain traps. 

Confidence

Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system.

Weather Forecast

Quite a bit of snow and wind in store for the forecast period. We’ll be watching these snowfall amounts closely.

SATURDAY NIGHT: Freezing level at valley bottom, strong south wind, 2 to 5 cm cm of snow possible.

SUNDAY: Overcast, freezing level at valley bottom, strong south/southeast wind, 2 to 10 cm possible during the day with another 2 to potentially as much as 15 cm Sunday night.

MONDAY: Overcast, freezing level at valley bottom, strong south/southwest wind, 5 to 15 cm of snow possible.

TUESDAY: Overcast, freezing level at valley bottom, strong south/southeast wind, 5 to 20 cm of snow possible.

Avalanche Summary

We received word of a snowmobile triggered wind slab avalanche north of Log Cabin that occurred on Thursday. Sounds like everyone is okay, but the avalanche occurred at treeline in relatively benign terrain which speaks to the reactivity of fresh wind slabs that may rest on surface hoar.

Snowpack Summary

Firm slabby snow can now be found in almost all wind exposed terrain. The predominant wind has been from the south but some north wind snuck in Thursday night meaning wind affected snow can be found on all aspects.    

In terrain around treeline there may be fresh wind slab sitting on surface hoar that is capable of producing large human triggered avalanches. See this MIN report that has a snow profile that features surface hoar down 40 cm below the surface.

A buried crust formed in early December can be found 60-100 cm below the surface, but most reports suggest the snow is quite well-bonded to this crust.

The lower snowpack is strong around White Pass, but there is potential for a generally thinner and weaker snowpack structure to exist in inland areas such as the Wheaton Valley. 

Terrain and Travel

  • Avoid freshly wind loaded terrain features.
  • Be aware of the potential for wide propagation.
  • Sheltered slopes at lower elevations will offer the best riding.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

Regioni coperte