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RegisterDec 25th, 2020–Dec 26th, 2020
Lizard-Flathead.
Recent snow & winds are creating reactive wind slabs. There are also buried weak layers. Large and destructive avalanches may be triggered by a person in steep or convex terrain. Continue to make conservative terrain choices as you safely enjoy your holidays.
A weak weather system will bring light snow, moderate west/southwes winds and cool temps for the weekend ahead of a building high pressure system.
Friday night: Mainly cloudy with scattered flurries trace-5cm new snow. Alpine low temperatures near -7 and freezing levels valley bottom. Ridgetop wind light to moderate from the west / southwest.
Saturday: Cloudy with scattered flurries trace-5cm new snow. Alpine high temperatures near -7 and freezing levels valley bottom. Ridgetop wind light to moderate from the west / northwest.
Sunday: Cloudy with sun breaks and isolated flurries. Alpine high temperatures near -7 and freezing levels valley bottom. Ridgetop wind light and variable gusting moderate.
Monday: Mix of sun and cloud. Alpine high temperatures near -9 and freezing levels valley bottom. Ridgetop wind light and variable west.
No new reports on Friday at the time of publishing, however the snowpack is still recovering from the recent storm which triggered a widespread avalanche cycle mid-week up to size 3. Natural avalanche activity may taper off a bit but the snowpack remains primed for human triggering, especially in periods of active wind-transport.
On Thursday there were a few explosive triggered size 1 avalanches were reported and large explosive controlled avalanches from nearby regions.
On Wednesday numerous storm slabs up to size 1.5 were triggered with explosives. This MIN from Tunnel creek also reports numerous large avalanches on cross loaded features at treeline.
On Tuesday, a widespread natural avalanche cycle up to size 3 was reported from the lizard range with many avalanches reported from northerly aspects.
Please consider sharing your observations on the Mountain Information Network. Thank you to those that have already submitted this winter!
30-60 cm of recent snow blanketed the region by Tuesday morning and has been blown by moderate to strong winds in exposed treeline and above since then. Moderate to strong west and southwestern winds created significant ridgetop snow re-distribution onto lee slopes. Wind slabs will likely remain reactive to human triggers, and are the most reactive during periods of moderate to strong winds. Cornice development may be found along ridgecrests and deep windslabs on lee slopes.
Recent snow fell on a variety of old surfaces including a buried melt-freeze crust reported below 1700m and surface hoar reported around treeline. This MIN has some great photos and snow tests that show new snow (10-20cm) is not bonding well to this recent rain crust.
A persistent slab 70-130 cm thick now sits on the early December crust. This persistent weak layer, with facetted crystals and surface hoar crystals above and/or below it is reaching a tipping point. Deeper in the snowpack are two hard melt-freeze crusts that formed in November that may have some weak crystals around them. This potential avalanche problem is dormant at this time, however; it remains on our radar.