Watch for wind slabs in unusual locations. Conditions are trickier at treeline and below where buried surface hoar is still capable of producing large human triggered avalanches. Check out the Forecaster Blog
here.
Summary
Confidence
Moderate - Forecast snowfall amounts are uncertain on Tuesday
Weather Forecast
SUNDAY NIGHT: Clear periods. Alpine temperatures near -18C. Ridgetop winds light from the south.MONDAY: Mix of sun and cloud with isolated flurries, trace accumulation. Alpine temperatures near -15C. Ridgetop winds light from the south.TUESDAY: Cloudy with scattered flurries, 5-10 cm accumulation. Alpine temperatures near -10C. Ridgetop winds moderate from the south.WEDNESDAY: Cloudy with scattered flurries, 5-10 cm accumulation. Alpine temperatures near -8C. Ridgetop winds light to moderate from the southeast.TUESDAY: Broken cloud cover, freezing level at valley bottom, around -20 C in the alpine, light variable wind at most elevations with moderate to strong southwest wind at ridgetop, a few centimeters of snow possible.
Avalanche Summary
Strong to extreme wind Friday night into Saturday initiated a natural wind slab avalanche cycle. Wind slab avalanches to size 2.5 were reported on all aspects and occurring above 2000 m. Check out
this MCR report of a skier triggered wind slab from an east facing aspect at 2370 m in the adjacent Glacier National Park region on Saturday.A persistent weak layer that was buried in mid-January continues to be reactive to human triggers. This layer is sensitive enough for avalanches to trigger remotely (from a distance). Activity on this interface continued through Friday as skiers triggered avalanches to size 1.5 on north through northeast facing terrain between 1650 and 1900 m. At higher elevations (2000-2300 m) small wind slabs were reactive to skier traffic on all aspects including a size 2 skier triggered avalanche on a west aspect while skiing over a roll.Human triggered avalanches size 1.5 to 2.5 were widespread last week on a variety of aspects at treeline and below.
Snowpack Summary
20-70 cm of recent new snow sits on wind slab, surface hoar (feathery crystals), facets (sugary snow) and a crust on sun-exposed slopes. In many areas, recent winds have formed wind slabs on all aspects due to shifting wind directions. The most notable feature in the snowpack at this time is a persistent weak layer that was buried in mid January, which is now buried 40-90cm. This layer consists primarily of surface hoar, however there is also a crust associated with it on sun-exposed slopes. This layer is the most prominent at treeline and below, and continues to produce avalanches.
dsaly,
Avalanche Canada
