Avalanche Forecast

Wednesday was a busy day for avalanche control with helicopter explosive deployment initiating numerous large avalanches (size 2). A mix of persistent and storm slabs occurred with depths up to 50 cm and running lengths between 100 and 200 m.

Explosive control in the south of this forecast region produced many small to large avalanches (size 1 to 2.5) All of these persistent slab avalanches failed at depths of 60 to 80 cm and run lengths of up to 180 m.

Monday and Tuesday was very active with skier controlled avalanches and one skier accidental small avalanche (size 1) this was all combined with a widespread natural avalanche cycle occurring. This ongoing avalanche cycle produced numerous small to large (size 1-2) avalanches. These avalanche primarily failed on surface hoar that was buried in the middle of December as well stepping down to the persistent weak layer buried mid November. A number of noted avalanches reported occurred in terrain that had been previously heavily compacted, these observations and reports, support an overwhelming sense that the snowpack is currently weak, fragile and unsupportive.

Additionally, a number of these avalanches stepped down to ground as the lower snowpack is faceted weak and unconsolidated.

If you are headed into the backcountry please consider filling out a Mountain Information Network report.

A period of warm and wet weather has moistened and settled the upper snowpack with rain reported up to the 2100m elevation. The upper storm snow totals of 50 cm that have settled are now a 30 cm reactive storm slab that overlies the mid December surface hoar layer.

The mid November persistent slab layer consists of surface hoar, facets, or a crust and is buried now down 40 to 80 cm deep.

Generally the mid and lower snowpack is facetted and weak.

Alpine snowpack distribution is variable, with depths ranging from 70 to 140 cm.

Thursday Night

Becoming Cloudy, very light snowfall; trace amounts. Light southwest winds 20 km/h. Freezing levels remain below 200 m with alpine highs of -10°C.

Friday

Cloudy, very light snowfall; 1 to 3 cm. Light southwest winds 15 km/h. Freezing levels near 700 m with alpine highs of -7°C.

Saturday

Cloudy, very light snowfall; trace amounts. Light to moderate southwest winds 15 to 40 km/h. Freezing levels rise mid day to 500 m with alpine highs of -9°C.

Sunday

Becoming clear with no precipitation forecast. Light northwest winds 15 km/h. Freezing levels 0 m with alpine highs of -12°C.

More details can be found in the Mountain Weather Forecast.

• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
• Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
• Travel in alpine terrain is not recommended.