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Avalanche Forecast

Archived

Mar 16th, 2023–Mar 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, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

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

Hazard will rise to considerable in the alpine during peak daytime heating.

Wind slabs may remain reactive to human triggering primarily on northeast slopes at treeline and above.

Confidence

Moderate

Avalanche Summary

On Wednesday, a few natural wind slabs were reported up to size 1 and explosive control produced several cornice falls up to size 2.5 and wind slabs to size 1.

On Tuesday, a few human-triggered storm and wind slab avalanches were reported up to size 2. Natural cornice failures and dry loose avalanches were also seen to size 1.

Natural and human triggered avalanche activity is possible throughout the weekend with rising freezing levels and solar radiation.

Snowpack Summary

Surface snow will likely become moist to ridgetop on solar aspects by the afternoon. Cornices loom over ridgelines and may become weak during periods of solar radiation and warming.

Up to 40 cm of recent storm snow seems to be settling and bonding to the old buried snow surfaces which consist of crusts on solars and faceted snow on polar aspects. However, at upper elevations shady, sheltered aspects may still host fairly unconsolidated loose snow. Strong southwest wind have formed reactive wind slabs on lee slopes at treeline and in the alpine.

Deeper in the mid-pack a couple of crusts with facets sitting above them can be found at treeline and above down 90 to 200 cm.

The remainder of the mid and lower snowpack is well-settled and strong.

Weather Summary

Thursday Night

Clear with some cloudy periods. Alpine temperatures near -4. Wind southeast 10 km/hr and freezing level valley bottom.

Friday

A mix of sun. Alpine temperatures near -1 degrees. Winds south 15-30 km/hr. Freezing level 1700 m.

Saturday

A mix of sun and cloud. Alpine temperatures near -1 degrees. Wind southeast 10-30 km/hr. Freezing level 1700 m.

Sunday

Cloudy with isolated flurries. Winds 10-20 km/hr from the southeast. Alpine temperatures near -1 with freezing levels 1800 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Closely monitor how the new snow is bonding to the crust.
  • Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

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.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

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.