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Avalanche Forecast

Dec 29th, 2017–Dec 30th, 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
2: Moderate
The avalanche danger rating below treeline will be moderate
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: North Columbia.

Continued slow accumulation of new snow Friday night into Saturday just before a more stable and clearing weather pattern sets in for the rest weekend.

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

SATURDAY: 5-10cm overnight Friday into Saturday then a mix of sun and cloud / Light west wind / Alpine temperature -15 SUNDAY: Mix of sun and cloud / Light northwest wind / Alpine temperature -10 MONDAY:  Mix of sun and cloud / Light west wind / Alpine temperature -5

Avalanche Summary

Recent reports show continue to show numerous human triggered and natural loose dry avalanches to size 1 in steep, sheltered terrain. Expect continued potential for triggering loose dry avalanches in steep terrain and consider the potential to trigger persistent slabs as the load continues to increase on top of the mid December persistent weak layer.

Snowpack Summary

20-30cm of low density new snow has buried a recently formed layer of weak feathery surface hoar and/or sugary facets. A layer buried mid-December that consists of surface hoar, sun crust and/or sugary facets is now down approximately 40-60cm.The bond at this old snow interface is of critical importance in areas where the overlying snow has consolidated into a slab. The most concerning areas are those that saw pronounced surface hoar development before the storm, such as sheltered areas at and below treeline, sheltered northerly aspects in the alpine, or anywhere the surface hoar formed on top of a sun crust. Recent snowpack tests show wide ranging reactivity on this weak layer but suggest that it may be most reactive on northerly aspects. A rain crust that formed in late November is now buried 80-110cm deep. Recent reports from the southwest end of this region suggests it may be reactive in steep, variably loaded terrain features in the alpine.

Avalanche Problems

Wind Slabs

Recent northwest, west and southwest winds have created wind slabs in the lee of terrain features.
Use ridges or ribs to avoid pockets of wind loaded snow.Be cautious as you transition into wind affected terrain.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Persistent Slabs

A weak layer of surface hoar buried 30-50 cm deep has potential to be reactive in areas where the overlying snow has settled into a cohesive slab.
Sluffs may trigger deeper instabilities.Watch for signs of slab formation, such as whumpfing and shooting cracksApproach steep open slopes cautiously at and below treeline where buried surface hoar may exist.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1 - 2