Continued snowfall, strong southwest wind & warm temps have created an upside down & heavily wind affected snow surface. Human triggered storm slabs are likely, especially at upper elevations. 5 to 15 cm Saturday night into Sunday will add to the 30+ cm of snow that fell Friday.
We're expecting 5 to 15 more cm Saturday night into Sunday with continued strong southwest wind. This will add to the 30+ cm of new snow that fell Friday into early Saturday. The new snow will need time to settle and stabilize, especially at upper elevations where it's been formed into stiffer slabs by the strong wind.
The series of warm storms continues...
SATURDAY NIGHT: Freezing level at valley bottom, strong south/southwest wind, 5 to 10 cm of snow.
SUNDAY: Broken cloud cover, freezing level at valley bottom, strong southwest wind, 1 to 5 cm of snow expected during the day with potential for another 5 cm Sunday night.
MONDAY: Overcast, freezing level rising as high as 1500 m, strong to extreme south/southwest wind, 5 to 15 cm of snow possible during the day with another 5 to 10 cm possible Monday night.
TUESDAY: Broken cloud cover at dawn clearing to just a few clouds by sunset, freezing level at valley bottom, strong northwest wind, 1 to 5 cm of snow possible.
Our field team took a quick look around Saturday while the road was closed. They found evidence of a natural avalanche cycle to size 1.5 with crowns up to 30 cm in depth. Interestingly, this kind of activity was found in upper treeline and alpine terrain. More details here.
The avalanches that impacted the highway Friday night were reported as four size 2 avalanches that started high and ran full path. These were likely wind fuelled storm slab avalanches.
On Thursday a skier triggered avalanche was reported from the "Eggnog gully" which overlooks Tutshi lake to the south. The soft slab was 50 cm in depth, 10 m across and ran 10 to 15 m down into dense fir trees. The skier was not caught in the avalanche. The avalanche likely ran on surface hoar.
The rather warm storm produced just over 30 cm of snow Friday into early Saturday. This adds to the storm snow that has accumulated over the past several days which has been accompanied by moderate to strong south/southwest wind as observed in this MIN post. Continued snowfall is expected through the weekend. Wind affected snow is on the surface in all but the most sheltered terrain creating an "upside down" snow surface condition.
Around Log Cabin, around 70 cm of snow may overlie a layer of surface hoar. This layer was the culprit of avalanche activity during the week of Monday, January 4th. This layer has not been reported elsewhere in the region.
A buried crust from early December can be found 60-100 cm below the surface, but most reports suggest the snow is well-bonded to it.
The lower snowpack is strong around White Pass, but there is potential for a generally thinner and weaker snowpack structure to exist in inland areas, such as the Wheaton Valley.
