Forecast freezing levels and precipitation amounts are uncertain Monday night through Tuesday. If precipitation falls as snow and is at the upper end of estimates, then avalanche danger will remain at HIGH in the alpine.
Summary
Confidence
Moderate - Forecast snowfall amounts are uncertain on Tuesday
Weather Forecast
TUESDAY: Flurries, accumulations 10-20cm Monday night into Tuesday and another 5-10cm though the day / Moderate to strong southwest wind / Alpine temperature -2 / Freezing level 1000mWEDNESDAY: Isolated flurries / Light to moderate southwest wind / Alpine temperature -7THURSDAY: Isolated flurries / Light to moderate south wind / Alpine temperature -6
Avalanche Summary
On Monday numerous natural and explosives controlled storm snow avalanches were reported to 2 and 2.5 on all aspects in the alpine and tree line. There was also a natural cornice triggered size 3 storm slab avalanche on a north east aspect in the alpine.Several large and very large avalanches have occurred on weak layers buried deep in the snowpack in the last week (including natural activity up to Size 3), highlighting that dangerous avalanche conditions exist within the region. Explosive control work last Friday and Saturday produced numerous storm slab avalanches Size 2-2.5, as well as several large, destructive Size 3-4, slab avalanches that failed on the mid-December and late-November layers, with crowns from 150-250 cm deep.
Snowpack Summary
There is possibly moist snow or a crust on the snow surface up to 1700m as a result of a high freezing level on Monday through Monday night. About 60-100cm of settled storm snow now covers a layer of surface hoar on sheltered aspects (especially prominent from 1400-1900 m) and sun crust on solar aspects, that was buried mid-January. Beneath the mid-January interface lie a number of very concerning buried weak layers. A layer of surface hoar from early-January is buried 90-110 cm below the surface. A weak layer buried mid-December (predominantly surface hoar and/or a sun crust) is around 120-160 cm below the surface at treeline and below treeline elevations. A rain crust with sugary facets buried late-November is near the bottom of the snowpack and is now up to 200-250 cm below the surface. All of these layers remain active and have produced recent large, destructive avalanches.
mbender,
Avalanche Canada
