Avalanche Forecast
Issued: Feb 9th, 2019 5:50PM
The alpine rating is Wind Slabs and Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Moderate -
Weather Forecast
Cold, dry, arctic air continues to dominate the weather pattern for the foreseeable future.SATURDAY NIGHT: Freezing level at valley bottom, around -25 C in the alpine, light variable northerly wind at valley bottom, light southerly wind at ridgetop, no significant snowfall expected.SUNDAY: Clear skies at dawn with cloud cover beginning to increase around lunch, freezing level at valley bottom, around -20 C in the alpine, light southerly wind at all elevations, no significant snowfall expectedMONDAY: Scattered cloud cover, freezing level at valley bottom, around -15 C in the alpine, light southwest wind at valley bottom, moderate southwest wind at ridgetop, no significant snowfall expected. A few centimeters of snow possible Monday night.TUESDAY: Scattered cloud cover, freezing level at valley bottom, around -15 C in the alpine, light variable wind at most elevations with moderate to strong southwest wind at ridgetop, a few cm of snow possible.
Avalanche Summary
A couple of smaller (size 1-1.5) slabs were ski cut on east aspects at 1700-1800 metres in the Fernie area over the past two days. These slabs were 40 cm deep and described as storm slabs, failing at our most recent new snow interface. Strategies for avoiding this storm slab problem mirror those for avoiding the persistent slab problem currently driving our Special Public Avalanche Warning.A 50 cm-deep size 1.5 persistent slab was triggered with a ski cut on Monday. This occurred on a north aspect at 1720 metres in the Fernie area. This is the latest of several recent observations of persistent slab avalanches failing on the persistent weak layer that was buried in mid-January. It was more widely reactive during and immediately after the storm this past weekend. The persistent weak layer producing these avalanches is described in the Snowpack Summary below.The past few days have also produced reports of wind slabs reacting to ski cutting and to explosives in the Fernie area. Sizes ranged from 1-2 and results have been focused on northeast to northwest aspects.
Snowpack Summary
Around 60 mm of precipitation fell last Friday. Above 1600 m, this produced 30-40 cm of new snow which has since been redistributed by strong winds from both north and south. It may sit on weak and feathery surface hoar crystals in shaded and sheltered areas. Below 1600 m, the precipitation fell mainly as rain and formed a new melt-freeze crust on the surface.Above 1600 metres, the mid-January layer of surface hoar and/or crust is now buried around 40 to 60 cm deep. The surface hoar is found on shaded and sheltered slopes and is most prominent between 1600 m and 1900 m. The melt-freeze crust is found on south aspects at all elevations. Slabs that exist above a combination of surface hoar and crust are likely to be particularly reactive. This layer is the subject of our Special Public Avalanche Warning.The remainder of the snowpack is generally well-settled. Thin snowpack areas, such as in the east of the region, may hold weak and sugary faceted grains near the base of the snowpack.
Problems
Wind Slabs
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Feb 10th, 2019 2:00PM