Watch for changing conditions throughout the day on Sunday. The Avalanche Danger may be higher than posted by the afternoon.
Summary
Confidence
Moderate - Forecast snowfall amounts are uncertain on Sunday
Weather Forecast
On Sunday expect 10-15cm of new snow to fall throughout the day (with higher amounts forecast for the Diamond Head/ Squamish Valley areas). Generally overcast skies and light flurries are forecast for Monday and Tuesday. Ridgetop winds will be moderate and southerly on Sunday, becoming light on Monday and Tuesday. Freezing levels should hover around 1850m on Sunday morning and then drop gradually to about 1600m throughout the forecast period.
Avalanche Summary
On Friday, there was an anomalous size 2.5 slab avalanche on an unsupported rocky face on the northwest corner of Mt Fissile (in the Fitzsimmons Range) at about 1900m. Although the sliding layer is unknown, the avalanche was thought to have been triggered by warming. There have also been numerous reports of solar-triggered cornice falls. Some cornice falls have been large (up to size 3), but most have only entrained surface snow. New snow and wind on Sunday will create new wind slabs at higher elevations.
Snowpack Summary
The snow surface consists of a sun crust or moist snow on sun-exposed slopes (depending on the time of day), dry settled powder on shady slopes (cool temperatures have maintained good snow quality), and pockets of fresh wind slab in lee and cross-loaded terrain features near ridge crests. In general, the snowpack is strong and well-settled throughout with no notable persistent weaknesses. Cornices are reported to be large and fragile. New snow and wind on Sunday will form fresh wind slabs at higher elevations while rain will saturate the upper snowpack below treeline.
jlammers,
Avalanche Canada
