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Avalanche Forecast

Feb 10th, 2012–Feb 11th, 2012
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
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: Sea To Sky.

Confidence

Fair - Forecast snowfall amounts are uncertain on Sunday

Weather Forecast

Saturday: Flurries possible with light southerly winds. Freezing level around 1400 m. Sunday: Light precipitation starting late in the day, with amounts of around 5 mm expected. Freezing level around 1300m, winds light southerly. Monday: A ridge of high pressure builds brining a dry day with sunshine. Freezing level around 1200 m.

Avalanche Summary

The last avalanche reported from this region occurred on Wednesday, when a natural cornice fall occurred. This large trigger pulled out a size 3 slab avalanche from the slope below on a north aspect at 1800 m.

Snowpack Summary

Light amounts of new snow (5-10 cm) has buried an assortment of old snow surfaces comprising, depending on location, crusts, old wind slab, surface hoar and surface facets. The crusts formed on all aspects at lower elevations and on steep solar aspects higher up. Old wind slabs were on a variety of aspects behind exposed terrain features. The surface hoar (5-10mm) was most prominent at and above the recent cloud associated with inversion conditions. Surface facets have grown particularly on northern aspects where colder temperatures have persisted. In general the snowpack is now well bonded in most locations. A mid-pack layer of concern is a rain crust (buried on Feb 1st) now down 10-40 cm, which exists up to about 2000 m. This may have potential to become reactive with additional snow load in areas where additional crusts do not lie above it, such as north aspects at treeline. Lower layers include a mid-January crust (down 50-100 cm), and a mid-December crust (down up to 200 cm); these now only present concerns in shallow snowpack areas. The average snowpack depth at 1650m is around 240cm.

Avalanche Problems

Wind Slabs

Fresh snow with moderate SE winds have formed wind slabs in the immediate lee below ridgelines and behind terrain features.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Cornices

Cornice fall may trigger slabs on the slopes below. Give cornices a wide berth when traveling on ridgetop, or on slopes below.

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 2 - 5