Avalanche Forecast

Archived

Apr 15th, 2014–Apr 16th, 2014

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

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.

Regions

Northwest Inland.

This bulletin has been produced using very limited field data. If you've been out in the mountains we'd love to hear about what you've seen. Observations can be sent to [email protected]

Confidence

Poor - Due to the number of field observations

Weather Forecast

Tonight and Wednesday: A frontal system is forecasted to approach the coast spreading a trace to light amounts of precipitation (~5 mm in water equivalent) into Wednesday. Freezing levels around 1300 m with light South East winds. Thursday: Light to moderate precipitation is expected (~15 mm) with freezing levels around 1300 m and light winds from the South West. Friday: A break in precipitation and a mix of sun and cloud. Freezing levels around 1800 m and light South winds.

Avalanche Summary

No new avalanches were reported.

Snowpack Summary

Light precipitation amounts may fall on the South Eastern corner of the region on a snow surface that consists of a melt-freeze crust in most areas, hard windslabs lee of recent strong South West winds or dry powdery snow in wind sheltered areas in the alpine and treeline. Snowpack test results from last Saturday indicated touchy conditions in the alpine where the windslabs had formed. Cornices are also large and potentially weak.The early February crust/facet layer is down 150 - 200 cm. This destructive layer should become less likely to trigger with forecast cooling.

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.

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.