Avalanche Forecast

SATURDAY NIGHT: Cloudy with clear periods and isolated flurries, Trace accumulation. Winds light to moderate Northwest. Alpine low temperatures -12 with freezing levels to valley bottom.  

SUNDAY: A mix of sun and clouds with isolate flurries. Winds light to moderate Southwest. Alpine High temperature -7 C, with freezing levels near 800m

MONDAY: Cloudy with flurries, accumulation Trace to 5cm. Winds light to moderate Northwest gusting strong. Alpine high temperatures -5, lows to -11, with freezing levels rising to 1100m.

TUESDAY: Cloudy with localized Snow, accumulations Trace to 10cm, with amounts diminishing to the south. Winds Southwest moderate to strong Southwest, gusting extreme. Alpine high temperatures -6 C and lows -9, with freezing levels rising to 1400m.  

Early reports from Saturday suggest an increase in number and size of Natural and human triggered avalanche activity from recent rapid snow loading and recent strong winds. Very Large (Size 3-3.5) natural and explosive controlled Avalanches were observed from extreme terrain in the higher mountains and along the highway corridor from North and South Aspects.  

There have also been many reports of large (Size 2) remotely and human triggered avalanches at treeline in the Monashees and northern portions of the region as well as many small (size 1-1.5) human triggered avalanches. There was also an increase small (Size 1) human triggered avalanches in the southern portion of the region down 20-40cm on Surface Hoar at treeline.  

On Friday there were many reports of small and large (up to size 2.5) human triggered avalanches down 25-45cm on Surface Hoar. These avalanches were reported on all aspects (from South to North) and ranged from 1000m to 2400m.  

Check out this MIN From the 29th that reports signs of instability near Mt. MacPherson.   

Recent snowfall amounts of 5-30 cm from Friday into Saturday's storm bring total snow overlying the widespread layer of Surface Hoar layer to 35-60 cm. Higher amounts were reported in the north of the forecast region. Winds were moderate to strong from the Southwest as new snow fell. This new snow likely formed widespread wind affect and wind slab in Alpine and exposed treeline locations, particularly near ridges. 

Not only may there be weakness within this recent storm snow, but a significant load has been added to an already problematic Surface Hoar layer that was was reported to be between 10 and 20 mm in size. This surface hoar layer is showing variability in its reactivity and distribution, but has been reported at all elevations and aspects. Recent warm temperatures have built slab like properties in this snow, particularly at mid and low elevations, making the persistent layer more reactive as evidence in the avalanche discussion. As surface snow continues to gain slab properties with more snow, wind, and fluctuating freezing levels, activity on this layer is expected to increase and avalanches may continue to grow in size.

The mid and lower snowpack is generally well-settled and strong.

• Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
• Be aware of the potential for large avalanches due to the presence of buried surface hoar.
• Avoid terrain traps such as gullies and cliffs where the consequence of any avalanche could be serious.
• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.