Boletín de aludes

Yukon

Feb 20 – 22, 2020Avalanche Canada
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Archivado · caducó 7 years ago

Peligro de aludes

Sat
Sun
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
Sin grado
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Lo esencial

Conditions have changed dramatically over the last 48 hours as temps have risen & strong southwest winds have blown. Wind slabs are now widespread. More snow and wind are incoming and fresh slab formation is likely. Seek out wind sheltered terrain if you venture into the storm.

Problemas de aludes

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–2.5

    We've had steady and strong south/southwest wind Monday through Wednesday which has stripped many slopes and welded hard slabs into others. Now we're going to add quite a bit of new storm snow to the problem along with a whole heap of wind. Wind fuelled storm slabs are expected to be problematic, but on the thinner side Thursday. All bets are off Friday though if we actually get the 10 to 20 cm of snow on Thursday night. This is a time of change and we need to give the snowpack time to adjust.

Confidence

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

Weather Forecast

The Yukon has been one of the few stormy spots in Western Canada recently, a trend that continues through the forecast period. We’ve been watching the weather and forecast closely, and it’s looking like the southwest wind will remain strong. There’s also high likelihood that the region will pick up significant snowfall beginning Thursday night.

WEDNESDAY NIGHT: Strong southwest wind, freezing level at valley bottom, 5 cm of snow expected.

THURSDAY: Overcast, strong to extreme southwest wind, freezing level at valley bottom, 5 to 10 cm of snow expected during the day, 10 to 20 cm expected Thursday night.

FRIDAY: Overcast, strong southwest wind, freezing level at valley bottom, 10 to 20 cm of snow possible.

SATURDAY: Overcast, strong southwest wind, freezing level at valley bottom, 5 to 10 cm of snow possible.

Avalanche Summary

Our field team found a fresh wind slab in their travels on Tuesday, details here. This is the kind of fresh slab formation that is expected to continue through the forecast period.

Snowpack Summary

Conditions have changed quite a bit in the last 48 hours. We've gone from overnight low temps around -20 C on Feb 17th to an overnight low Tuesday night of -6 C. Wind has picked up dramatically, they have been steady moderate to strong out of the south/southwest for the last 48 hours. This has stripped some slopes of snow and welded hard slabs into others, but there has been some recent wind slab activity too. 

Snow depths at White Pass are around 160 cm at our wind protected Fraser study plot. Deeper locations (higher terrain west of the highway) have more than 200 cm, while on the east of the highway depths are around 185 cm. It's reasonable to expect a thin snowpack composed mainly of sugary facets in the Wheaton Valley, and thinner wind-scoured alpine areas.

Terrain and Travel

  • Minimize exposure during periods of heavy loading from new snow and wind.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Seek out sheltered terrain where new snow hasn't been wind-affected.

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