TUESDAY Night: Mainly cloudy with flurries, light southwest wind, alpine temperature -14 CWEDNESDAY: Cloudy with sunny breaks, light west wind, alpine temperature -13 C.THURSDAY: Mix of sun and cloud, light to moderate southeast wind, alpine temperature -10 C.FRIDAY: Flurries, accumulation 5-10 cm , light southwest wind, alpine temperature -7 C
Many small and large wind slab avalanches were triggered on Monday and Sunday. They were triggered naturally and by skiers. Most of the avalanches were on west and north aspects, but there were reports of avalanches on all aspects. They occurred at all elevation bands.The mid-January persistent weak layer described in the Snowpack Summary has recently been reactive to human triggers, although activity has decreased in the past few days. The most recent activity was on Friday, as skiers triggered small avalanches on north and northeast slopes between 1650 and 1900 m.The most recent deep persistent slab was reported on Saturday, which was very large (size 3.5) and triggered naturally on a northeast aspect at 2950 m. The slab was 400 cm thick and 150 m wide.
The top 10 to 20 cm of snow has been affected by recent strong wind from variable directions. Expect to find wind slabs in lee terrain features in exposed terrain. This snow may be particularly touchy where it sits on a weak layer of feathery surface hoar crystals, as seen here
. Beneath this lies two weak layers of surface hoar, which have produced large avalanches in the region. The layer that was buried at the end of January is around 30 cm deep and the layer buried mid-January is between 40 and 90 cm deep. The mid-January layer may also be associated with a melt-freeze crust on southerly aspects. These layers are most prominent at treeline and below treeline elevations. Recent avalanches on the mid-January layer have been mostly in the northern half of the region.The remainder of the snowpack is generally well-settled. However, there have been sporadic reports of very large avalanches that have released near the base of the snowpack, suggesting that instability exists in isolated locations. Most of the avalanches have been in the high alpine. There has been about one report a week for the past month, suggesting it is a low probability but very high consequence problem.