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

Dec 15th, 2013–Dec 16th, 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 avalanches possible, human triggered probable.
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 unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

South Columbia.

Confidence

Fair - Intensity of incoming weather systems is uncertain on Tuesday

Weather Forecast

Monday: Light snowfall / Moderate westerly winds (with extreme gusts) / Freezing level at 800mTuesday: Moderate snowfall / Moderate southwesterly winds (with extreme gusts) / Freezing level at 800mWednesday: Possible clearing / Light winds / Freezing level at valley bottom

Avalanche Summary

On Saturday, several natural storm slabs to size 2 were reported to have run on a variety of aspects and elevations. There have also been a number of size 2.5 and size 3 storm slabs which ran on north and south facing alpine terrain along the highway corridor through Rogers Pass. They occurred in response to ongoing snowfall, wind and rising temperatures.

Snowpack Summary

Although recent accumulations have been highly variable, up to 60cm of snow now overlies the weak faceted crystals or small surface hoar which formed during the last cold snap. Rising temperatures are reported to have enhanced slab properties forming cohesive surfaces and creating a more reactive "upside-down" snowpack. Moderate to strong southwest winds have created wind slabs in exposed high elevation terrain.As of late there has been no reported activity on the late-November interface which consists of sun crusts on steep south facing slopes and surface hoar in sheltered areas. This layer, buried between 60-80cm below the surface, is generally considered to be "stubborn" to trigger; however, avalanches at this interface could have nasty consequences.Weaknesses towards the base of the snowpack are mostly thought to be dormant at this time.

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.

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.