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

Mar 20th, 2013–Mar 21st, 2013

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Glacier.

Cornices are large and unsupported.  A few have failed recently, causing large avalanches.  The new storm snow will be a concern everywhere, however solar aspects are most problematic due to buried sun crusts.

Weather Forecast

A low will bring increasing precipitation today, with most intense accumulations occurring mid-day.  Upslope (westerly) locations will receive locally heavy amounts, accompanied by strong southerly winds.  Freezing levels will rise to 1300 m today, and drop tomorrow as a cold front follows.  Unsettled conditions will remain for tomorrow and Friday.

Snowpack Summary

Storm snow slabs exist in the alpine, but are sporadic.  Reports from north aspects (Dome Glacier) indicate the upper snow is well bonded; however avalanches to size 2.5 were observed yesterday from solar aspects in the Connaught drainage.  Where storm slabs rest on a buried suncrust-surface hoar combo (March 11), wide propagations can be expected.

Avalanche Summary

Numerous slabs were seen yesterday, mostly in the top 30-40cm.  Skiers on Mt. Sifton yesterday were able to cut a cornice to check the slope, and released a size 2.5-3 avalanche on a south aspect, 40cm deep x 100m wide.  Another size 2.5-3 slab was seen in the Asulkan drainage on Mt. Abbott. 

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Wednesday

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.

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.