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Avalanche Forecast

Archived

Apr 27th, 2014–Apr 28th, 2014

Alpine
Below Threshold.
Treeline
Below Threshold.
Below Treeline
Below Threshold.
Alpine
Below Threshold.
Treeline
Below Threshold.
Below Treeline
Below Threshold.
Alpine
Below Threshold.
Treeline
Below Threshold.
Below Treeline
Below Threshold.

Regions

Kootenay Boundary.

We are no longer issuing danger ratings for this region due to a lack of field data. Check out this forecasters blog post for more insight into managing the current conditions.

Weather Forecast

Synopsis: A strong upper ridge will build over the region on Monday and dominate through the week. This will bring mostly sunny skies, and moderate SW-W ridgetop winds. Freezing levels will rise to 1800 m on Monday and then climb steadily above 2000 m from Tuesday onward. No significant overnight freeze is expected.

Avalanche Summary

Expect loose wet avalanches in steep terrain if it is raining or during sunny periods, especially if the sun or rain is affecting the fresh snow. Spring squalls may bring locally heavy precipitation and new storm or wind slabs may develop in higher terrain if you see significant new snow accumulation. Cornices collapses have been reported during periods of daytime warming. Occasionally these heavy triggers have caused large deep slab avalanches on the slopes below.

Snowpack Summary

This is a broad general summary of conditions in the region based solely on recent weather data and previous snowpack information. It should be supplemented with local observations to help assess avalanche danger. Please refer to this document for additional snow and avalanche information and general travel advice. Over the last few days we have seen moderate amounts of moist or wet new snow mixed with showers or periods of rain below 1600-1800 m. Westerly winds have likely formed pockets of wind slab at higher elevations in lee of ridges and terrain features. The late January/early February persistent weak layer is deeply buried but could still wake up during periods of heavy precipitation (especially rain) or significant warming and solar radiation. Be particularly wary of this on large open alpine slopes. Cornices are large in some areas and should be given a wide berth.

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.