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RegisterMar 12th, 2018–Mar 13th, 2018
Olympics.
Shallow wet snow early Tuesday will make Loose-Wet avalanches possible on some steep slopes. Avoid slopes where even small avalanches may have large consequences such as above cliffs, creeks, and rocks. Older weak snow may still exist in the snowpack so avoid large open slopes that may still harbor this difficult to predict and manage avalanche problem. Give fresh cornices a wide margin of safety.
Clouds and mild temperatures Monday night will maintain shallow wet surface snow and limit a hard re-freeze. A weak front should spread light rain or wet snow over the Olympics Tuesday but amounts should be light. The precipitation should come with cooling through the day. This should allow for decreasing chance of Loose-Wet avalanches Tuesday and limit any Loose-Wet activity to below treeline. Stay away from slopes where even a small Loose-Wet avalanche may have higher consequences such as above cliffs, gullies, and creeks.
Recent warm weather and snowpack settlement has helped round and strengthen buried persistent weak layers. We have removed the Persistent Slab problem from the forecast problems, however this does not mean it is impossible to trigger a persistent slab in isolated areas, especially with a larger trigger such as a cornice fall.
Avoid large open slopes, especially slopes below large overhanging cornices.
Sunshine and temperatures in the 40's over the past few days has allowed for significant snowpack settlement and for a variety of surface conditions to develop. Firm melt-freeze crusts are forming overnight with shallow wet snow conditions in the afternoon.
The latest snowfall was 3-4 inches that fell Thursday night and early Friday. This shallow recent snow has undergone settlement consolidation over the past few warm and sunny days.
Older weak snow layers continue to be reported in the Olympics. On slopes that receive direct sun, several facet/crust layers may be found. A more widespread layer of weak sugary facets was found just above a very firm melt-freeze (2/8) crust formed in early February. The depth to this weak layer depends on aspect and elevation.
We have not received reports of recent avalanches in the Olympics other than small wet loose on steep sunny slopes.
There are no significant layers of concern below the 2/8 crust layer.
Observations
On Sunday as of 1 PM, NPS rangers reported generally small loose wet avalanches with one larger release caused by a partial cornice collapse.
On Saturday, Forecaster Robert Hahn and NPS Rangers found the 2/8 weak snow/crust interface in snowpits on a West aspect at 5300' and down 2.5 feet from the surface. No new avalanche activity was observed other than small wet loose avalanches on steep sunny slopes. North facing terrain still held drier settled powder.
On Wednesday March 7th, a NPS ranger traveled in the Victor Pass area and found many crusts with facets forming on south aspects. Near ridge-tops, the 2/13 weak layer was 8-12" down and 3 mm facets were observed. Mid-slope this layer was down 3-4 feet.