Avalanche forecast

Sea To Sky

Apr 3 – 4, 2018Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

A skiff of fresh snow covers variable surfaces below: Be alert for rapid changes under your skis or sled, and watch for fresh pockets of wind slab.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–2
    Recent south winds have formed wind slabs on northerly features near ridge crests. Slabs could be most reactive where they may be sitting on firm, scoured snow from earlier in the week.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3
    A weak layer of surface hoar or facetted crystals has been reactive especially where it may be sitting on a hard crust.

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Thursday

Weather Forecast

Only small amounts of snow on Wednesday with heavier snow fall (or rain) on Thursday-Friday. Freezing levels will slowly increase.WEDNESDAY: Snow (up to 5 cm, with more possible in the south) / Moderate south west wind / Alpine temperature -4 / Freezing level 500m rising to 1200m in the afternoon THURSDAY: Wet snow (10-20cm) or rain at lower elevations / Light to moderate south-west wind / Alpine temperature -3 / Freezing level 1400mFRIDAY: Cloudy with light flurries (5-10 cm possible in the morning) / Moderate south west wind / Alpine temperature -1 / Freezing level 1800m.

Avalanche Summary

On Tuesday, fresh wind slabs were reactive to ski cuts - but limited to size 1 - on immediate down wind (lee) features. On Monday, explosives control work triggered only a few size 1 wind slab avalanches in isolated terrain up in the alpine. On Friday a sled-triggered size 2 wind slab was reported near Grizzly Lake near Powder Mountain, on a north west aspect near 1750m. See the MIN post for more details. A week ago there was a size 1 avalanche that sympathetically triggered a size 3 persistent slab avalanche resulting in a fatality. This was on a northeast aspect at 2000m, 50cm deep. Additionally there were reports of natural persistent slab avalanches size 2.5-3 on southeast through northeast aspects between 1800 and 2000m. These were reported to have happened in the previous 24-48 hours. See this MIN post for similar details.

Snowpack Summary

We've been seeing regular amounts of light snow (2-10 cm each day) since Easter Sunday (with some locally higher amounts due to intense convective activity and gusty winds). Winds have been gusting strong, previously from the north and most recently the south.The end result is that snow conditions are wildly variable, with a skiff of new snow sitting on: melt freeze crusts on sunny aspects, scoured old hard wind slabs, isolated pockets of soft wind slab or soft snow giving decent skiing in some sheltered locations. See this MIN post for a good summary of conditions beyond the musical bumps. Old snow from a week ago rests on the March 21st interface, which has a very patchy distribution, but is mostly likely to be found on shady aspects between 1900m and 2250m. The March 21st interface has been giving variably moderate to hard resistant planar results, typically down 40-60cm on 1-2mm facets.The mid and lower snowpack are strong and well settled.

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