Avalanche Forecast

Low - Timing, track, or intensity of incoming weather system is uncertain

A cool unstable airmass moves into the region Saturday evening, which should deliver 2 to 10 cm of snow by daybreak Sunday. Sunday offers a brief break in the action before a second pulse arrives Sunday night. SUNDAY: Freezing level starting at valley bottom rising to 1500 m, 0 to 3 cm of snow during the day, moderate south winds. SUNDAY NIGHT: Freezing level holding at 1500 m, 2 to 20 cm of snow, moderate to strong south winds. MONDAY: Freezing level around 1400 m, 1 to 3 cm of snow, moderate southwest winds. TUESDAY: Freezing level starting around 800 m, rising to 1600 m, no significant snow expected, moderate SW winds. For a more detailed mountain weather forecast visit avalanche.ca/weather

On Friday avalanches ran naturally to size 2, while explosive control work produced avalanches up to size 2.5. Check out the Mountain Information Network for more details about a human triggered size 2 on a NW facing slope along the Bonnington Traverse. On Thursday reports included numerous natural avalanches up to Size 3 in response to heavy loading from snow, wind and rain. Most of the natural avalanches were storm and wind slabs, but a few persistent slabs also ran naturally on the late February persistent weak layer. Explosives and other artificial triggers (i.e. snow cats) produced additional Size 2-3 persistent slab activity, with remote and sympathetic triggers as well as 50-100 cm thick slab releasing from the impact of the dropped charge, before it exploded.

15 to 35 cm of fresh snow has fallen in the last 48 hours which has left 40 to 50 cm wind slabs on the leeward side of ridgecrests and mid-slope terrain features. These fresh storm and wind slabs are bonding poorly to a thin crust at lower elevations depending on the drainage and/or overloading lower density previous storm snow creating an unstable "upside down" upper snowpack that is sliding easily on a widespread rain crust, which extends into alpine elevations. A persistent weak layer buried late-February is typically down 60 to 100 cm and highly sensitive to human triggers as indicated by recent avalanche activity. This weakness is widespread buried surface hoar on sheltered slopes above 1700 m, and a crust potentially with associated facets on previously sun-exposed slopes (primarily south aspects).