Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Apr 9th, 2018–Apr 10th, 2018

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

Regions

South Coast Inland.

Expect changing weather on Tuesday: high freezing levels dropping over the day, intense rain switching to snow, and strong winds. Warming will weaken the snow and new snow will form fresh slabs. Be very cautious with these rapid changes.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

TUESDAY: Cloudy with rain switching to snow, accumulation 10 to 20 cm, strong to extreme southwest winds, alpine temperature 0 C dropping to -5 C, freezing level 2600 m dropping to 1400 m over the day.WEDNESDAY: Mostly cloudy with snowfall, accumulation 5 to 10 cm, light to moderate southeast winds, alpine temperature -4 C, freezing level 1600 m.THURSDAY: A mix of sun and cloud, light west winds, alpine temperature -6 C, freezing level 1500 m.

Avalanche Summary

Loose and slab avalanches were observed on Sunday. Loose wet avalanches were observed on all aspects in steep terrain, being triggered naturally and by humans. Check out this MIN report from the north of the region, which discusses a large wind slab avalanche in alpine terrain that was triggered by a skier. They also noted reactivity of the recent storm snow around 1700 to 1800 m. Widespread whumphing was observed in a drainage in the north of the region, which was suspected to have been on the late-March weak layer described in the Snowpack Summary.

Snowpack Summary

Warm temperatures have moistened the snow surface on all aspects and at all elevations.  At higher elevations, this overlies slabs formed from the weekend’s snow that fell with strong southwesterly winds.  On Tuesday, new snow will fall with strong winds, forming new wind slabs in lee features.  On ridges, cornices are reported to be large and fragile. At low elevations below treeline, recent rain has created moist or wet snow conditions.A weak layer consisting of surface hoar, facets, and/or a melt-freeze crust from late March is now buried about 50 to 100 cm. This layer is spotty in its distribution. It is mostly likely to be problematic on west, north, and east aspects between 1900 m and 2250 m.The mid and lower snowpack are well-settled and strong.

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.