Avalanche Forecast

Archived

Apr 23rd, 2014–Apr 24th, 2014

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

Below Threshold.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Regions

Northwest Inland.

Due to a lack of field observations, we are starting to transition to bulletins without Danger Ratings. Check out this Blog Post for more information on spring ratings.

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Thursday

Weather Forecast

Overnight and Thursday: Overnight freezing levels dropping down to 1000 metres and then rising up to 1500 metres during the day. Periods of broken skies overnight, and then mostly cloudy with light precipitation during the day. Winds light to moderate from the Southeast.Friday: Cloudy with light precipitation and not much overnight freezing. Winds light from the Southeast. Saturday: Winds becoming strong Southerly. Mostly cloudy with moderate precipitation falling as snow above 1000 metres.

Avalanche Summary

No new avalanches reported. We are no longer receiving professional daily reports for the region so public observations are really appreciated right now. If you are out in the mountains, send your observations to [email protected]

Snowpack Summary

Highly variable spring conditions are expected in the region. At lower below-treeline elevations the snowpack is typically wet and isothermal. It has not been refreezing overnight and is melting quickly. Between roughly 1000 and 1500m, the snowpack is undergoing daily melt-freeze cycles. The same conditions can be expected on sun-exposed slopes all the way to mountain-top. On higher elevation north-facing slopes, dry snow can be found. Recent strong S through W winds have scoured windward slopes and created wind slabs in leeward slopes. The early February crust/facet layer is typically down 1.5m or more. A smaller avalanche or a cornice fall may still have the potential to step down to this layer causing very large, destructive avalanches, especially during warm sunny periods.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.