Purcells

Large variation in storm snow totals occurred across the forecast region. The current danger rating is largely being driven by conditions in the south. If you have been out in the mountains, please send your observations to [email protected].

Fair - Due to the number of field observations

The arctic ridge of high pressure dominates the interior of British Columbia and will persist for the forecast period. Mainly clear, cold and dry conditions will prevail. Expect periods of moderate northerly winds and alpine temperatures to be chilly, -15C to -25C by Friday.

Explosive work today produced numerous avalanches to size 2 on north aspects in the alpine. In some areas (particularly the south), significant storm snow now overlies well preserved weaknesses which may be primed for rider triggering.

The snow distribution varies greatly across the region but average depth of snow at treeline is approximately 60-110cm.The southern portion of the region received substantially more snow (40-70cm) than the north in the past storm. The storm slab is sitting on top of various weak layers; surface hoar on sheltered, shaded slopes and a melt-freeze crusts on south facing slopes. In the south Purcells, there have been reports of preserved surface hoar crystals overlying a melt-freeze crust below treeline around 1500m. In this location, 70cm overlies this weak layer which produced very easy results in stability tests. Reports are sparse, but it is likely this same layer exists in sheltered locations in the alpine and at treeline. Digging deeper, the lower snowpack is fundamentally weak, composed of an early season crust (more prevalent on north aspects) and weak facetted crystals. The weight of new snow may be currently 'testing' these deeper layers and the additional load of a rider (particularly in shallow snowpack areas) may just be enough to tip the scale. If so, persistent slabs have the potential to produce large, destructive avalanches.