Bollettino valanghe

Lizard-Flathead

Mar 3 – 4, 2020Avalanche Canada
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Archiviato · scaduto 7 years ago

Pericolo valanghe

Thu
Fri
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
Apri la mappa completa

In sintesi

Cornices are the only significant problem on Tuesday. Give these things a wide berth, especially if you're travelling on ridge lines.

Problemi valanghivi

  • Cornices

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

    Cornices have grown large and loom over many ridge lines. These have the potential to fail naturally with the natural rise and fall of temperatures throughout the day, they could also fail if we get too close to them. Give these things a wide berth. Wind slabs are not expected to be much of a problem right now, but be aware of the potential for wind slabs in the highest elevation terrain.

Confidence

High - We have a good understanding of the snowpack structure and confidence in the weather forecast

Weather Forecast

A few weak frontal systems will graze the region this week with sustained mild temperatures.

MONDAY NIGHT: Cloudy with light snow, trace to 3 cm, strong southwest wind, freezing level around 1200 m with alpine temperatures around -4 C.

TUESDAY: Mostly cloudy with potential for a bit of midday sun, freezing level climbs from 1200 to 1700 m, moderate to strong west wind, alpine high temperatures around -2 C.

WEDNESDAY: 5-10 cm of snow overnight then possibly some sunny breaks in the afternoon, moderate to strong southwest wind, freezing level dropping from 1700 to 1200 m, with alpine temperatures dropping to -4 C.

THURSDAY: Mostly sunny, freezing level climbing from valley bottom to 2000 m in the afternoon, moderate southwest wind, alpine temperatures reach 0 C.

Avalanche Summary

No new avalanches were reported on Monday.

A cooling trend following Friday's warm up has neutralized the wind slab problem for the short term, but some folks skiing McD's on Sunday did find small wind slab "cookies" at high elevations, you can see more details in this MIN report. Cornices are still an issue though, there was a report of a size 2 natural cornice failure on Saturday, it did NOT initiate a slab when it impacted the slope below. Another chunk of cornice fall was reported on Sunday too.

Snowpack Summary

Friday was quite warm which settled the upper snowpack and resulted in a crust that can be found on the surface up to 2000 m on solar aspects and up to 1700 m on all other aspects. Wind slabs have grown old and tired, even at ridge crest. Wind slabs are unlikely to be a problem, except at the highest elevation and more extreme terrain near ridge crest. 

A thick rain crust that has facets associated with it sits 30-60 cm below the surface and can be found up to ridge top. We have only seen one avalanche on this layer since February 17th. The mid-pack is well settled and strong, but the base of the snowpack contains basal facets that are most prominent in shallow rocky start zones.

Terrain and Travel

  • Large cornice falls are dangerous on their own.

Regioni coperte