Archived

Avalanche Forecast

Dec 11th, 2017–Dec 12th, 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

1: Low

The avalanche danger rating at treeline will be low

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

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Northwest Inland.

Strong alpine temperatures will persist through the forecast period. Loose wet avalanche activity may occur on steeper slopes and terrain features.

Confidence

Low - Due to the number and quality of field observations

Weather Forecast

Strong Alpine temperature inversions persist through the forecast period.Tuesday: Mainly cloudy with ridgetop winds light to moderate from the west. Alpine temperatures 0 degrees above 1400 m. Wednesday: Mainly cloudy with ridgetop winds light to moderate from the south. Alpine temperatures plus 5 degrees above 1000 m.Thursday: Mix of sun and cloud. Light ridgetop winds with strong gusts from the southwest. Alpine temperatures near plus 5 degrees above 2000 m.

Avalanche Summary

No recent avalanches have been reported. Please submit your information to the Mountain Information Network. Give info get info.

Snowpack Summary

Snow surfaces are highly variable throughout the region. Solar and temperature crusts have formed on sun-exposed slopes, while stiff, stubborn wind slabs linger in lee alpine terrain. Surface hoar and surface facets have formed below treeline up to 1500 m Approximately 30-50 cm of storm snow now overlies two crusts that were buried near the end of November. These crusts are widespread and extend into the alpine. Although snowpack tests have previously shown hard results at these crust interfaces, more recent observations have been limited. Below these crusts, a well settled mid-pack overlies the late October crust near the base of the snowpack. This "crust/facet combo" layer is widespread and has been reactive to rider and remote triggers. It also continues to produce a variety of resistent to sudden snowpack test results.Average snowpack depths now total 80-140 cm at treeline elevations and up to 160 cm in the alpine. (Depths of up to 210 cm have been reported from the Howsons)

Avalanche Problems

Loose Wet

Loose wet avalanches may occur with warmer temperatures at upper elevations.

Use caution above cliffs where small avalanches may have severe consequences.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Wind Slabs

Stiff wind slabs may be rider triggered. Watch for triggering in higher elevation, wind-exposed terrain.

Be cautious as you transition into wind affected terrain.Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 2

Deep Persistent Slabs

The late October crust lies near the base of the snowpack with a thin layer of weak, sugary snow above it. This layer should be on a strengthening trend, but a heavy trigger in a thin snowpack area may still be enough to cause it to react.

Be especially cautious in shallow snowpack areas where triggering a deeper layer may be easier.Be aware of the possibility for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3