Avalanche Forecast
Issued: Feb 9th, 2018 4:06PM
The alpine rating is Storm Slabs and Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeHeads up! Large avalanches from above have the potential to reach run-out zones.Special Avalanche Warning in effect for the interior ranges. Copy this address to view details: http://bit.ly/2nSOUyX
Summary
Confidence
High -
Weather Forecast
The weather pattern has taken a dramatic shift as the arctic ridge becomes the dominant weather feature through the weekend, bringing colder temperatures and mostly clear skies.Saturday: Mostly sunny. Alpine temperatures near -8 and freezing levels at valley bottom. Ridgetop winds light from the West. Sunday: Mostly cloudy. Alpine temperatures near -9. Ridgetop winds light from the northwest.Monday: A mix of sun and cloud. Alpine temperatures -10. Light winds from the northeast.
Avalanche Summary
On Thursday, numerous large and destructive natural slab avalanches occurred through the region up to size 4 on all aspects and elevations. Avalanche control using explosives triggered numerous loose wet avalanches up to size 2 and a significant size 3 storm slab avalanche. These were reported from SE-SW slopes above 1900 m. Natural avalanche activity may spike again with the first hit of sun then start to taper off through the weekend with colder temps; however, slopes will remain primed for human triggers.
Snowpack Summary
Storm snow accumulations vary, showing 10-45cm across the region at upper elevations. Below 1800 m a surface crust exists. The new snow in the alpine has been redistributed to leeward slopes from strong northwest winds. This now brings 1- 2 m of settled snow sitting on three significant surface hoar/ crust layers that were formed early to mid-January, and back in December. Near the base of the snowpack a crust/ facet interface exists and will likely haunt us all season. These persistent weak layers that lurk within the snowpack are reactive, producing large and destructive avalanches. The snowpack is extremely complex and requires respect and diligence at this time.
Problems
Storm Slabs
Storm slabs are reactive. Natural avalanche activity may taper off, but slopes are primed for human triggers. The first hit of sun will likely trigger loose dry avalanches which could step down to deeper layers.
Travel in avalanche terrain is not recommended. Choose conservative, simple terrain.Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
The snowpack is complex and continues to produce very large avalanches on several weak layers buried below the surface.
Be mindful that deep instabilities are still present and have produced recent large avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 10th, 2018 2:00PM