Avalanche Forecast

Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system. Uncertainty is due to how buried persistent weak layers will react with the forecast incoming weather.

FRIDAY NIGHT: Snow with accumulations of 5-15 cm with more amounts in the Monashee Mountains and near the highest mountains of the region. Winds moderate southwest gusting Strong. Alpine low temperatures -10 C with freezing level dropping to 800 m.

SATURDAY: Cloudy with scattered flurries, accumulation Trace to 10 cm. Winds light to moderate west. Alpine high temperatures -9 with freezing levels to 1000m.  

SUNDAY: Morning flurries then a mix of sun and cloud. Winds light west. Alpine temperature -12 C with freezing levels near 800m

MONDAY: Cloudy with flurries, accumulation 5-15cm. Winds light southwest gusting strong. Alpine high temperatures -5, lows to -9 and freezing levels rising to 1400m

Many small (size 1 to 1.5) persistent slab avalanches were triggered by humans every day since Tuesday. They occurred at all elevation bands, between 1600 m and 2300 m, and generally on northwest to east aspects. Early reports from Friday suggest an increase in the number of large avalanches, including a few remotely triggered avalanches on North and East aspects in the Alpine and at treeline. Avalanches were commonly 20 to 40 cm deep and released on the surface hoar layer described in the Snow pack Summary. There were also reports of large natural avalanches on Solar slopes or in steep terrain.  

There is uncertainty as to how this persistent weak layer will respond to the continued loading of snow, but we expect avalanches to increase in size as the slab properties of the overlying snow pack increase.   

Friday night's forecast 5-15cm of new snow will result in a total of 35-50cm overlying the widespread layer of surface hoar that was reported to be between 5 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 Friday's warming trend, activity on this layer is expected to increase and avalanches may grow in size.

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

• 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.
• Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.