Avalanche Forecast

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

Thursday kicks off a multi-day snow event that should provide a nice re-set for the region. This is a dynamic period as northwest flow scoops up incoming weather systems off the east-pacific and directs them over the province. Take these snow totals with a grain of salt, amounts are changing quite drastically from one model run to the next. WEDNESDAY NIGHT: Freezing level near valley bottom, light variable wind at most elevations with strong northwest wind at ridgetop, trace of snow possible.THURSDAY: Overcast, freezing level near valley bottom, light southwest wind at most elevations with strong west/southwest wind at ridgetop, 5 to 15 cm of snow possible during the day, 10 to 20 cm possible Thursday night.FRIDAY: Overcast, freezing level at valley bottom, light southwest wind at most elevations with strong southwest wind at ridgetop, 10 to 20 cm of snow.SATURDAY: Broken cloud cover, freezing level at valley bottom, moderate to strong southwest wind, 1 to 5 cm of snow possible.

On Tuesday there was quite a bit of activity from solar aspects throughout the region. In the neighboring Glacier National Park region a size 3 avalanche was skier triggered on a steep southeast facing slope in the alpine. More details and photos here. Skier triggered avalanches from size 1.5 to 2.5 were reported from south and southeast facing terrain between 2300 and 2500 m. Clear skies allowed for the appearance of the increasingly strong late January sun all day which was likely a factor in these avalanches. The mid-January Surface hoar seems to be most sensitive in this region. On Tuesday a size 2.5 persistent slab failed naturally on a northeast facing feature at 1900. Two more reports came in Monday of skiers triggering persistent slab avalanches to size 1.5 on a variety of aspects between 1500 and 1800 m. This MIN post and this one (from the neighboring South Columbia region) do a great job of illustrating the nature of this problem which is most prevalent between 1400 and 1900 m. This MIN is a bit older, but it also offers a great visual of this mid and low elevation problem. This interface will likely wake up as storm snow begins to stack up over the weekend.

Incoming storm snow is unlikely to bond well to the old surface which is a mix of sastrugi, stubborn old wind slabs, facets, crust and surface hoar. Saturday delivered warmth and strong to extreme wind out of the west, south, southwest and northwest. This left a crust up to 3 cm thick on steep south and some west facing aspects and redistributed quite a bit of snow into wind slabs in lee features at and above treeline. These wind slabs have grown old and tired and are probably only suspect in extreme terrain. The warmth also allowed 25 to 50 cm of snow to continue to consolidate above the mid-January persistent weak layer (PWL). This PWL is made up of large surface hoar that is most prevalent at and below treeline, with enhanced reactivity noted between 1400 and 1900 m. On steep solar aspects this interface presents as a crust, there may be locations where the surface hoar actually sits on the crust.The middle and lower portions of the snowpack are generally well-settled and strong.