Avalanche Forecast
Regions: Purcells.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain on Monday
Weather Forecast
The Pacific frontal system will push through the interior regions Sunday night through Monday. This will bring light-moderate snow amounts and strong SW-W winds.Monday: Snow amounts 10-20 cm. Alpine temperatures near -5. Ridgetop winds moderate from the West. Freezing levels 800 m.Tuesday: Mainly cloudy with some flurries. Alpine temperatures near -14. Ridgetop winds moderate from the West gusting strong. Freezing levels back to valley bottom.Wednesday: Cloudy, and dry. Alpine temperatures near -8. Ridgetop winds light from the West.
Avalanche Summary
On Sunday, explosive controlled size 2-3 slab avalanches were reported. These all failed on the early October crust. Currently widespread loose dry sluffing from steeper terrain slopes and features has been reported. With new snow and strong ridgetop winds, you can expect the avalanche danger to rise Monday/ Tuesday.
Snowpack Summary
Low density new snow covers stiff, dense wind slabs in exposed lee terrain at and above treeline. Average snowpack depths at treeline elevations are 100-130 cm. In the upper 80 cm of the snowpack a couple persistent weak layers exist, comprising of surface hoar and a facet/ crust combo. This interface has produced variable results with snowpack tests, and operators are keeping a close eye on them as the load above increases and/or a slab develops.A bigger concern, especially in the Northern part of the region where the snowpack is thinner and more variable is weak faceted and depth hoar crystals combined with a crust from early October. This is now down around 80-120 cm. This deep persistent weakness may be stubborn to trigger, especially in deeper snowpack areas, but the sensitivity to triggers likely increases in shallower locations, especially on steep, convex, north-facing slopes.
Avalanche Problems
Wind Slabs
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 4
Deep Persistent Slabs
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 2 - 5