Lingering wind slabs may still be reactive to human-triggering in exposed terrain at higher elevations.
In the east of the region, buried persistent weak layers may still be reactive to human-triggering in north-facing terrain around treeline.
Lingering wind slabs may remain reactive to human-triggering in exposed high elevation terrain. These may remain reactive for longer than normal where they overlie a firm crust.
Surface hoar layers buried in January have been responsible for two recent size 2 avalanches in the east of the region. Various combinations of crusts above and below these layers have made the distribution and sensitivity of this problem difficult to pin down.
Be cautious on northerly steep open slopes at and just below treeline where these layers are most likely to have been preserved and remain reactive.
One more day under the influence of high pressure before the first in a series of storm systems arrives on Sunday.
Friday Night: Mainly clear, light NW wind, treeline low around -15 °C.
Saturday: Mainly sunny, light to moderate SW wind, treeline high around -5 °C.
Sunday: Light snowfall 4-8 cm, moderate to strong SW wind, treeline high around -4 °C.
Sunday night and Monday: Snowfall heavy at times, moderate to strong SW wind, treeline high around -1 °C.
On Thursday, four skier triggered avalanches were up to size 1.5 were reported on south and southeast aspects at treeline in the northwest of the region. Some small natural and human-triggered sluffing was also reported on steep slopes.
Earlier in the week, several size 1-1.5 skier-triggered wind slabs were reported near ridge crests. Surface hoar layers buried in January have also been responsible for two recent size 2 avalanches in the east of the region.
20-30 cm of snow typically overlies a variable and potentially weak interface from mid-February which includes a melt-freeze crust, facets, and/or surface hoar. So far this interface has only been a concern in wind-loaded terrain where a slab has formed. In exposed terrain at higher elevations, recent strong northeast winds have caused extensive scouring and wind slab formation. Due to the northerly wind direction, reverse loading occurred meaning there may be wind slabs lingering in unusual places.
Two layers of buried surface hoar sit in the upper snowpack which have been most reactive in sheltered areas at treeline. These are now down around 40-70 cm deep. While these layers had gone dormant in many parts of the region, they still remain reactive in snowpack tests in the east of the region and continue to be responsible for sporadic avalanches, including two avalanches earlier this week.
The lower snowpack is well consolidated, with a crust/facet layer from early-December found around 100-200 cm deep. It is currently considered dormant, but could become active again later this season. Check out the forecaster blog for more information.
