Avalanche Forecast

Moderate -

WEDNESDAY Night: Clear periods, light southeast wind, alpine temperature -15 C.THURSDAY: Mix of sun, cloud and isolated flurries, light to moderate southeast wind, alpine temperature -7 C.FRIDAY: Flurries, accumulation 5-10 cm , light to moderate southwest wind, alpine temperature -6 CSATURDAY: Flurries, accumulation 10-15 cm, light west wind, alpine temperature -8 C

Several size 1-1.5 windslab, storm slab and persistent slab avalanches were reported from areas in the south of the region on Tuesday. These were predominantly at treeline and in the alpine on all aspects. The mid-January persistent weak layer described in the Snowpack Summary has recently been reactive to human triggers, although activity has decreased in the past few days. The most recent activity was on Friday, as skiers triggered small avalanches on north and northeast slopes between 1650 and 1900 m.The most recent deep persistent slab was reported on Saturday, which was very large (size 3.5) and triggered naturally on a northeast aspect at 2950 m. The slab was 400 cm thick and 150 m wide.

Up to 25 cm of new snow has fallen in the southern portion of the region (south of Nakusp) in the past 48 hours. 5-10 cm has fallen further north. This new snow is sitting on previously wind-affected surfaces, sugary facets or feathery surface hoar. Beneath this lies two weak layers of surface hoar, which have produced large avalanches in the region. A layer that was buried at the end of January is around 30 cm deep and a layer buried mid-January is between 40 and 90 cm deep. The mid-January layer may also be associated with a melt-freeze crust on southerly aspects. These layers are most prominent at treeline and below.The remainder of the snowpack is generally well-settled. However, there have been sporadic reports of very large avalanches that have released near the base of the snowpack, suggesting that instability exists in isolated locations. Most of the avalanches have been in the high alpine. There has been about one report a week for the past month, suggesting it is a low probability but very high consequence problem.