Snowfall amounts may vary widely across the forecast region. Higher than forecast snow amounts could dramatically increase the hazard. forecast.
Confidence
Fair - Forecast snowfall amounts are uncertain
Weather Forecast
A series of Pacific low pressure systems will bring snow to the forecast area for the next 5 to 7 days. Forecast models vary on amounts and some parts of the area may see larger amounts of precipitation.Wednesday night: Freezing Level at valley bottom Trace of precipitation as the front moves to the east, winds moderate to strong from the south west at ridge top.Thursday: Freezing level: 1300m; Another wave of moisture through the interior on Thursday with light to locally moderate amounts of precipitation. A minor clearing on Thursday night before the next system. Winds from the south west, moderate to strong at ridge top.Friday: Freezing level: 1100m; Yet another wave will bring more snow to the region, with continued moderate to strong winds at ridge top.Saturday: Freezing level around 900m A bit of a break in the weather on Saturday. Flurries with a trace of precipitation, light winds at ridge top.
Avalanche Summary
Reports of numerous size 1 to 1.5 skier controlled and natural avalanches up to size 2 in the past 24 hrs. We expect the number of reported avalanches to increase with the snow loading and strong upper elevation winds.
Snowpack Summary
Some parts of the Purcells have received up to 40+cm of storm snow in the past 48 hrs on a variety of weak surfaces(surface hoar, facets, sun crust) These weak layers will be problematic for the near future and it will take time for the new snow to bond with the old surfaces. Significant weak layers of large surface hoar and facetted snow are now buried 10 to 30 cm below the new snow surface. These weak layers are expected to remain a problem for the foreseeable future. The rest of the snowpack is generally well consolidated. Forecast strong winds at ridge tops will redistribute the new snow and form wind slabs on lee slopes. A facet/crust weakness near the bottom of the snowpack has gone dormant for the most part. The depth of this layer makes triggering an avalanche unlikely but the consequences would be very serious.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.