Avalanche forecast

Sea To Sky

Feb 2, 2018Avalanche Canada
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Archived · expired 9 years ago

Avalanche danger

Sat
Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
1 · Low

Highlights

New snow and extreme winds will keep the avalanche danger elevated at higher elevations on Friday. The avalanche danger is expected to rise throughout the day.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–2
    New snow and wind on Thursday night are expected to form new wind slabs in higher elevation lee terrain. This new snow overlies older storm slabs which are gaining strength but may remain sensitive to large triggers in steep, unsupported terrain.
  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5
    Recent heavy snowfall and high winds have formed fragile new cornices. These monsters may surprise with nasty consequences. Use extra caution around ridge crests.

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Thursday

Weather Forecast

Friday: 10-20cm of new snow / Strong to extreme westerly winds / Freezing level at 1400mSaturday: Light flurries / Light and variable winds / Freezing level at 1200mSunday: 5-10cm of new snow / Light southwest winds / Freezing level at 2300mNote: Confidence is low for forecast wind values and precipitation amounts for Saturday and Sunday.

Avalanche Summary

Explosives control on Tuesday and Wednesday triggered lingering storm slabs at treeline and above - mostly in the size 1.5-2 range. The exceptions were a size 3 and a size 3.5 slab that were explosives-triggered on rocky, cross-loaded alpine slopes. The exact failure plane of these avalanches is unknown.Looking forward, continued snow and wind on Friday morning is expected to promote a new round of wind slab activity in higher elevation lee terrain.

Snowpack Summary

As of Thursday morning 10-15 cm of new snow had fallen and was redistributed by strong southerly winds into fresh wind slabs in exposed lee terrain. At lower treeline and below, generally light amounts of snow now overlie a melt-freeze crust which formed during last Monday's warm storm. The new snow adds to the 170cm of snow that fell during the last few weeks of January. These series of storms were accompanied by strong to extreme winds which resulted in extensive scouring and impressive cornice growth in upper elevation terrain. These accumulations sit on a crust from mid-January which generally shows signs of bonding to the overlying snow; however, it has the potential to "wake-up" with a large trigger such as a cornice fall.Below this, the snowpack is thought to be generally strong and well-settled.

Regions covered