Choose mellow slopes, and use caution around ridgetops and convex rolls. Retreat to low angle terrain if you see shooting cracks, or moist, heavy snow that is snowballing or pinwheeling.
The heaviest snowfall for this storm cycle is arriving with the weakest wind.
Recent wind has been in the moderate to strong range, mostly from the southwest. These winds formed reactive windslabs that are now buried by more storm snow.
Signs of reactive windslab may now be harder to spot, so use extra caution around ridge tops and convex rolls.
Wet loose avalanches are possible on steep low elevation slopes if the temperature is above freezing.
In some places, rain may be falling on dry snow for the first time, which can rapidly destabilize the snowpack.
The heaviest snowfall from the ongoing storm is expected to be during the day on Sunday. Clouds are forecasted to clear as temperatures cool on Monday.
Saturday Night: Mostly cloudy. 0-5 cm of snow expected. Light to moderate southwest wind. Freezing level dropping to between 250 m and 500 m.
Sunday: Mostly cloudy. 10-20 cm of snow expected. light southwest wind, trending to strong at higher elevations. Freezing levels between 500 m and 1000 m.
Sunday Night: Mostly cloudy. 0-5 centimeters of snow expected. Strong southwest winds, trending to extreme west at higher elevations. Freezing level around 1250 m in the south end of the region, 500 m in the north.
Monday: Cloud clearing through the day. Possible trace of snow expected. Wind decreasing over the day, becoming moderate northerly by the afternoon. Freezing levels dropping to valley bottom.
Tuesday: Partly cloudy. No new snow expected. Light variable winds. Treeline high around -3 °C.
On Friday, a professional operation northeast of Hazleton reported a large, rider triggered wind slab avalanche below a ridgetop on a northwest aspect in the alpine. Several other people had ridden the slope just before it avalanched. The avalanche was an average of 70 cm deep and 50 m wide, and it ran for 150 m.
On Thursday in the Seaton area, our Northwest field team saw a size 2, rider-triggered windslab avalanche on a northeast aspect in the alpine. The avalanche looks like it was triggered from a thin, rocky spot below a convex roll. See their Mountain Information Network (MIN) post here for photos and more details.
Also on Thursday, a professional operation in the Ningunsaw area reported an explosive triggered size 3 deep persistent slab avalanche that failed on basal facets. This avalanche was on a generally northeast facing feature around treeline, and it started just below a ridge crest.
Remember that a lack of observed avalanches does not necessarily mean that there is a lack of avalanche activity. If you are getting out in the backcountry, and have conditions information, or even just good vibes and good photos to share, consider making a post on the Mountain Information Network (MIN).
By the end of the day on Sunday, total snowfall for this storm is forecasted to reach 30-60 cm. Recently, strong southwest winds formed reactive wind slabs in exposed areas. Wind speed is forecasted to decrease while snowfall continues, so wind slabs that remain reactive to rider triggers may be buried by new snow.
Terrain below treeline that sees moderate to heavy rainfall could continue to be unstable due to loose-wet avalanches or an upside down upper snowpack.
With the mild temperatures and ongoing wind, cornices are reported to be growing larger.
The base of the snowpack is composed of crusts and weak faceted grains, particularly in thin snowpack areas. While these layers have generally gone dormant in the region, they still have the possibility of waking up with new snow load or warming, and wind slab avalanches may still have the potential to step down to these deeper layers in isolated areas.
