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Avalanche Forecast

Archived

Apr 16th, 2023–Apr 17th, 2023

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

Regions

Sea To Sky, Brandywine, Garibaldi, Homathko, Spearhead, Tantalus, Sky Pilot.

Recent snowfall and wind has left dangerous avalanche conditions in alpine terrain. Carefully investigate the bond of storm snow and give it time to strengthen before committing to avalanche terrain.

Confidence

Moderate

Avalanche Summary

Reports from the early stages of the storm include a few small (size 1) storm slabs triggered by skiers (an example in this MIN report from Sky Pilot). We suspect some natural avalanches occurred later during the peak of the storm on Sunday, most likely on wind-loaded slopes.

Snowpack Summary

Sunday's cold front will have left 20 to 30 cm of new snow across the region. Storm snow overlies a crust at treeline and below. In the alpine, the snow is heavily wind-affected and sits over a variety of layers including dry snow and wind slabs on north aspects and sun crusts and wind-pressed snow on south aspects. Several crusts can be found in the upper snowpack. The lower snowpack is strong and bonded.

Weather Summary

Sunday night

Cloudy with scattered flurries bringing 5 to 15 cm of snow, 30 to 40 km/h southwest wind, treeline temperatures drop to -10 °C.

Monday

Cloudy with flurries starting mid-afternoon with up to 5 cm of snow by the evening, 40 km/h southeast wind, treeline temperatures warm to -5 °C.

Tuesday

Mostly cloudy with scattered flurries bringing 5 to 10 cm of snow, 20 km/h southwest wind, treeline temperatures around -5 °C.

Wednesday

Scattered flurries bring another 5 to 10 cm of snow, 30 km/h southeast wind, treeline temperature climbing to -2 °C.

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.
  • Carefully monitor the bond between the new snow and old surface.
  • Be especially cautious as you transition into wind affected terrain.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.

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.