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Archived

Avalanche Forecast

Feb 7th, 2015–Feb 8th, 2015
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: Glacier.

More rain is expected today for lower elevations. New storm snow up high needs time to stabilize.

Weather Forecast

Moist and warm pacific fronts continue to hit Rogers Pass this weekend.  Moderate SW winds gusting to strong and light rain below treeline with moist snow above.  The next major system arrives Sat evening with increased winds and 16mm of precipitation by Sunday afternoon. Freezing levels remain just below treeline for the rest of the weekend.

Snowpack Summary

Intense rain in the last 36hrs has left the upper snowpack moist or wet to around 2100m. The Jan 30 surface hoar/crust layer, which exists up to 2200m, is down 30-70cm, depth will depend on elevation. Jan 15 surface hoar layer is down 70-110cm and was reactive in artillery highway avalanche control.

Avalanche Summary

Yesterday saw a widespread natural cycle producing large avalanches with moist deposits at lower elevations. Artillery highway avalanche control produced numerous size 3-3.5 avalanches with with wide propagating slabs on all aspects. Avalanches ran far, in some cases to the end of the run outs.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Avalanche Problems

Storm Slabs

100mm of precipitation that fell as rain and snow is now sitting over the January 30 weak layer. This will make conditions dangerous until the rain and snow stop and temperatures cool down.
The new snow will requires several days to settle and stabilize.Minimize exposure during periods of heavy loading from new snow, wind.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Very Likely

Expected Size: 2 - 3

Persistent Slabs

Recent intense precipitation and warm temperatures have the ability to reawaken deeper layers. Storm slabs avalanches may step down and propagate on these deep instabilities.
If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 3 - 4

Loose Wet

Recent intense precipitation has fallen as rain at lower elevations. With higher freezing levels, expect that the surface snow will be saturated making loose wet avalanches likely.
Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 2 - 3