Purcells

The snowpack in the Purcells this season is exceptional, and not in a good way. We've summarized our thoughts on this precarious snowpack in the latest forecasters blog here. Take it easy out there, this is not the time for the big lines.

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

Thursday kicks off a multi-day snow event across the province, but the latest model runs suggest that this system will not produce much snow for the Purcells. That being said, 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 at valley bottom, light variable wind at most elevations with strong northwest wind at ridgetop, trace of snow possible.THURSDAY: Broken cloud cover, freezing level near valley bottom, light southwest wind at most elevations with strong west/northwest wind at ridgetop, trace of snow possible during the day, 1 to 5 cm possible Thursday night.FRIDAY: Overcast, freezing level near valley bottom, light southwest wind at most elevations with strong southwest wind at ridgetop, 3 to 10 cm of snow.SATURDAY: Broken cloud cover, freezing level near valley bottom, light to moderate southwest wind, trace of snow possible.

On Tuesday a skier triggered a small storm slab on a very steep east facing feature around 2100 m. A size 2 wind slab was triggered when ice fall impacted a north facing slope at 2600 m.On Monday a natural size 2.5 wind slab avalanche was observed on a steep south facing feature at ridgecrest (2700 m). The wind slab had a crown 60 cm in depth. A cornice failure produced a size 3.5 deep persistent slab on a northeast facing slope at 3000 m that ran for 2 km. The crown was reported to be up to 300 cm in depth which suggests it failed on the late October weak layer at the very bottom of the snowpack. There's a great MIN report from Monday of a deep persistent slab that failed naturally on a SW facing feature at treeline.There is a great MIN report from January 22nd that shows a natural avalanche (size 3.5) in International Basin, also on the deep persistent layer. Check it out here.

The current surface is a mix of sastrugi, old wind slab, facets, sun crust and a bit of surface hoar. Last weekend was warm & extreme wind came out of the south, southwest and northwest. This left a robust crust (up to 4 cm thick) on steep south facing aspects and redistributed snow into wind slabs which have grown old and tired. The warmth allowed 10 to 35 cm of snow to settle into a slab above the mid-January persistent weak layer (PWL) which is made up of large surface hoar that is most prevalent at and below treeline. On steep solar aspects this interface presents as a crust, there may be locations where the surface hoar actually sits on the crust.The snowpack is harboring a nasty weak layer near the ground composed of weak facets above a crust. This interface continues to produce sporadic avalanches that are very large and destructive. Avalanches triggered on this weak layer take the entire seasons snowpack with it and have resulted in numerous close calls and serious incidents. This layer is most likely to be triggered from zones where the snowpack is thin and weak. Rock outcroppings and ridge crests around large open slopes and bowls in the alpine are particularly suspect