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Archived

Avalanche Forecast

Jan 12th, 2015–Jan 13th, 2015
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
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
3: Considerable
The avalanche danger rating in the alpine will be considerable
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
3: Considerable
The avalanche danger rating in the alpine will be considerable
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.

Incoming precipitation with mod SW winds will drive the wind slab problem. Choose conservative terrain at treeline and above.

Confidence

Fair - Due to the number and quality of field observations

Weather Forecast

An upper level trough will move into the area from the Pacific tonight and into Tuesday bringing light precipitation, with 5 to 10 cm of new snow at upper elevations. A bit of clearing on Wednesday, then more light precip. on Thursday and Friday. Winds from the S-SW, moderate to strong at upper elevations throughout the forecast period.  Freezing levels should remain around 500 m but may spike to 1800m on Wednesday, then return to  around 500 m on Friday. 

Avalanche Summary

No reports of avalanche activity yesterday.

Snowpack Summary

Recent winds have created wind slabs on lee aspects in exposed terrain. Below the recent storm snow is a rain crust at lower elevations and a temperature crust formed on the surface above treeline in some locations from the recent temperature inversion. In the mid-pack a surface hoar layer has been reported, although it appears to be spotty in distribution. Near the base of the snowpack is a November crust-facet combination.

Avalanche Problems

Wind Slabs

Recent wind slabs should be bonding with the mild temperatures, but incoming precipitation will rebuild the wind slab problem.
Choose well supported terrain without convexities.>Use ridges or ribs to avoid pockets of wind loaded snow.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3

Persistent Slabs

A small avalanche or a cornice failure might trigger deeply buried instabilities.
Be aware of the potential for large, deep avalanches.>Use caution around convexities, ridge crests, rock outcroppings and anywhere else with a thin or variable snowpack.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 2 - 6