Avalanche Forecast
Issued: Dec 17th, 2019 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
MBender,
Avalanche Canada
Storm snow accumulating over the last few days has gradually increased the load on a buried layer of surface hoar crystals. Expect human triggered avalanches to be likely.
Summary
Confidence
Moderate - Forecast snowfall amounts are uncertain.
Weather Forecast
TUESDAY NIGHT: Flurries, accumulation 5-15 cm, moderate southwest wind, alpine high temperature -6 C.
WEDNESDAY: Scattered flurries, light to moderate southwest wind, alpine high temperature -7 C.
THURSDAY: Scattered flurries, moderate southwest wind, alpine high temperature -8 C.
FRIDAY: Snow, accumulation 10-20 cm, strong southwest wind, Alpine high temperature -3 C.
Avalanche Summary
Expect human triggered avalanches to be likely in the coming days as the load gradually builds over a recently buried layer of surface hoar.
On Monday there were several natural storm and wind slab avalanches reported on all aspects between 1800 and 2300 m. On Sunday there were several reports of skier triggered size 1 storm slab avalanches up to 30 cm deep on north south and east aspects at treeline.
On Saturday there were two reports of skier triggered persistent slab avalanches size 1-1.5. One was on a south aspect at 2200m and was about 25-45 deep.
Snowpack Summary
30-60 cm of recent snow has accumulated above a widespread layer of large, feathery surface hoar crystals. New snow is expected to continue to accumulate above this layer over the next few days and possibly make it more sensitive to human-triggering.
A weak layer formed in late November is now buried around 1 m below the surface. This is the layer of concern relating to the listed persistent slab avalanche problem. The weak layer may present as surface hoar, a crust, facets or a combination, depending on elevation and aspect. Below this, a variety of crusts from late October are buried deeper in the snowpack.
Problems
Storm Slabs
Snow gradually accumulating above a buried layer of weak surface hoar will create a touchy storm slab problem. The conditions are primed for human triggered avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A couple of weak layers formed in late November and early December are now sitting about 1+ m below the surface. This layer may present as surface hoar, a crust, facets or a combination of those, depending on elevation and aspect.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 18th, 2019 5:00PM
