Avalanche Forecast

Moderate - Timing, track, or intensity of incoming weather system is uncertain on Wednesday

On Wednesday morning a strong winter storm will arrive on the BC coast. Rather warm air and precipitation is expected to spread into the interior Wednesday afternoon resulting in snowfall through Thursday evening. The freezing level should fall back towards valley bottom Thursday night. Friday and Saturday look cool and calm with another system set to move into the interior on Sunday. WEDNESDAY: Broken cloud cover, freezing level rising to around 900 m, moderate south/southwest wind, 2 to 6 cm of snow possible in the afternoon, 10 to 20 cm possible Wednesday night.THURSDAY: Broken cloud cover, freezing level around 1500 m, moderate to strong southwest wind, 1 to 5 cm of snow possible. FRIDAY: Scattered cloud cover, freezing level beginning at valley bottom rising to around 1200 m in the afternoon, light west/southwest wind, trace of snow possible.

On Monday warm temperatures and direct solar induced natural avalanches to size 3.0 on solar aspects, the largest ran on a steep south/southwest face in the alpine. Human triggered avalanches to size 1.5 were reported on north and northeast facing terrain above 2000 m, likely running on the early January interface.On Sunday there was a widespread natural avalanche cycle to size 3.5. These very large avalanches were running on southwest, south and southeast facing alpine features and were triggered by a combination of above freezing alpine temperatures and direct solar input. Three size 2.5 avalanches likely failing on the early January interface were reported to have ran naturally on a southwest facing slope from 1900 m down to 450 m, covering a snowmobile access road south of Revelstoke. Another remotely triggered size 2.0 avalanche was reported on a northeast facing feature at 2050 m that failed on the early January weak layer.

Spotty freezing rain Tuesday may have left a slight "glaze" on the surface which adds to the crust that is being widely reported from many locations, high elevation north is likely one of the few crust-free zones. Fresh surface hoar 3 to 10 mm in size has been reported to at least 2100 m, possibly higher. We can probably expect a touchy storm slab to form on this interface as storm totals exceed 10 cm.There are two active Persistent Weak Layers (PWL) that we are monitoring.The first PWL is known as the early January interface, it is 30 to 90 cm below the surface. It is composed of surface hoar on sheltered slopes as well as sun crust on steep solar aspects and is present at all elevation bands. Recent snowpack tests have shown sudden results with moderate loads.The second PWL is the mid-December facet/surface hoar/crust combination that is now buried 70 to 150 cm deep and is most problematic at and below treeline. This interface is not thought to be present in the alpine.The November rain crust down 125 to 200 cm is thought to have gone dormant for the time being.