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Avalanche Forecast

Archived

Feb 4th, 2023–Feb 5th, 2023

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Below Threshold.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Below Threshold.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Below Threshold.

Regions

Long Range Mountains, Corner Brook, Gros Morne, Northern Peninsula.

In the wake of the storm, stick to simple terrain on Sunday. As fair weather settles in this week and inspires you to explore, be sure to start small and ease into terrain cautiously. Wind slabs are likely to remain triggerable by riders and uncertainty around a buried weak layer (and its potential to produce large avalanches) is on our minds.

Confidence

High

Avalanche Summary

We expect a widespread natural storm slab avalanche cycle to have occurred during the storm Friday and Saturday. Rider-triggered wind slab avalanches will remain likely for a few days after the storm.

Prior to this storm, recent avalanche observations have been limited to small wind slabs and cornice falls reported by our field team.

If you're heading out into the mountains, please consider sharing your observations on the Mountain Information Network!

Snowpack Summary

30-60 cm of new snow has been redistributed by strong northwesterly to westerly winds. Expect to find deep wind slabs on leeward aspects, and scouring on exposed windward aspects. After a milder storm over Sunday night, wind-ravaged surfaces may be blanketed by 5-15 cm of fresh snow.

The mid snowpack consists of 30-100 cm of recent January snow, poorly bonded to a crusty underlying lower snowpack.

Weather Summary

Saturday night

Intense localized snow squalls 3-5 cm per hour accompanied by strong northwesterly wind gusting 110 km per hour through the evening. Snowfall and wind easing mid night. Temperature -12 to -15 C.

Sunday

Scattered flurries through the day, intensifying in the evening as the next system approaches. Westerly wind 30 km/h switching southwest and increasing in the afternoon. Temperatures rising through the day, peaking around -5 C overnight.

Monday

5-15 cm of new snow overnight, clearing to a mix of sun and cloud. Light westerly wind. Alpine temperatures near -5 C in the morning dropping to -12 C through the day.

Tuesday

Sunny, light easterly wind, alpine high temperature around -10 C.

A quiet stretch of weather until late in the week.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Start with simple terrain and gather information before thinking about more committing features.
  • Avoid freshly wind loaded terrain features.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.