Archived

Avalanche Forecast

Feb 23rd, 2017–Feb 24th, 2017

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Northwest Inland.

The deep persistent weak layer of sugary facets continues to be a concern for people triggering large avalanches.

Confidence

High -

Weather Forecast

Tonight: Strong northeast winds, scattered flurries and -20 in the alpine. Friday: Mix of sun and cloud or high overcast with moderate northeast winds and alpine temperature -12. Saturday: Cloudy with light snow (3-5 cm), moderate to strong northwest winds, and alpine temperature -10. Sunday: Mostly sunny with moderate northeast winds and alpine temperature -15.

Avalanche Summary

No new avalanches reported.

Snowpack Summary

10-15 cm of recent storm snow has been transported by the wind, and now sits on a variety of old surface conditions including isolated wind slabs, pockets of soft snow (5-10 cm deep), sun crusts, and surface hoar. A supportive rain crust exists below 1000 m. A layer of surface hoar that was buried on February 10th may exist 30-60 cm below the surface, but there's a fair bit of uncertainty regarding the reactivity and distribution of this layer. A stiff mid pack sits above weak sugary snow near the ground. Although possibly dormant, this basal weakness has the potential to produce very large destructive avalanches.

Avalanche Problems

Deep Persistent Slabs

A weakness at the bottom of the snowpack is lingering and may be triggered in shallow snowpack areas or by the weight of smaller avalanches.

Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.Avoid steep convexities or areas with a thin or variable snowpack.Avoid lingering in runout zones.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 4

Wind Slabs

Changing wind directions may develop new wind slabs on south through west aspects. Old wind slabs may continue to linger on other aspects.

Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind loaded snow.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2