Avalanche forecast

Sea To Sky

Mar 4, 2017Avalanche Canada
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Archived · expired 10 years ago

Avalanche danger

Sat
Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Strong SW wind and fresh snow Friday night may fuel another round of natural avalanches while most of us sleep. Light wind and lack of snowfall on Saturday may appear benign, but the mountains are currently primed for human triggered avalanches.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    2–3
    Strong winds from Friday will continue into Friday night promoting the development of fresh sensitive wind slabs in exposed terrain. Watch for especially deep and touchy slabs on wind loaded slopes this weekend.

Confidence

Moderate - Wind speed and direction is uncertain on Saturday

Weather Forecast

A deep upper trough is moving through BC this weekend. A few disturbances are expected to continue to deliver moderate precipitation into southwestern BC through Friday night. As the trough exits Saturday, snowfall is expected to cease as the freezing level drops to valley bottom. Sunday offers a break in the action before modest snowfall begins again on Monday.FRIDAY NIGHT: 5 to 15 cm of snow, strong to extreme southwest wind.SATURDAY: Overcast skies, freezing level near valley bottom, light SW wind, no significant precipitation expected. SUNDAY: Broken skies, freezing level near valley bottom rising to 500m in the afternoon, light SW wind, no significant precipitation expected. MONDAY: Overcast skies, freezing level around 500m, moderate SW wind, 1 to 5 cm of snow. Visit avalanche.ca/weather for a more detailed mountain weather forecast.

Avalanche Summary

On Thursday control work produced numerous storm slab avalanches on all aspects to size 1.5. A MIN report from Thursday https://bit.ly/2lnYiMC indicates significant slab development at and above treeline. Reports from Wednesday include several rider and explosive triggered storm slab avalanches up to size 1.5 and natural soft wind slab avalanches up to size 2. Of note was a remotely triggered size 1.5 windslab. This slab was triggered from 7m away with a 30cm crown, running on facets overlying a crust that formed mid-February.

Snowpack Summary

20 to 60cm of low density fresh snow is bonding poorly to previously wind-affected surfaces (e.g. scoured crust, hard sastrugi, or stubborn wind slabs) in exposed areas, or around 20cm of faceted snow in sheltered areas. Strong south/southwesterly winds have scoured wind-exposed slopes and deposited deep drifts on lee aspects. A crust from mid-February is below all this, down around 50 to 70cm. Recent snowpack tests have been giving moderate sudden results in facets above this crust. The mid and lower snowpack are well settled and strong.

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