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Avalanche Forecast

Feb 28th, 2012–Feb 29th, 2012
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
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
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Sea To Sky.

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Wednesday: Snow amounts up to 15 cm arriving by the am. Light snow near 5 cm before noon. Ridgetop winds 30km/hr from the South. Treeline temperatures near -11. Thursday: Snow amounts 5-10 cm. Ridgetop winds moderate from the West. Treeline temperatures near -8. Possible solar influence in the afternoon if clouds break. Friday: A strong westerly flow brings light snow amounts. Strong ridgetop winds from the West. Freezing levels at valley bottom.

Avalanche Summary

Reports of natural activity seemed to dwindle on Monday. One natural size 2 occurred on a SW aspect @2400m. The crown was 40-50 cm deep, 40 m wide, and ran 300 m in length. Few, small size 1 skier triggered, and explosive triggered avalanches were reported on steeper, convex terrain features, and gully features. With forecast snow and wind, I suspect avalanche conditions will remain touchy, and susceptible to rider triggers through the forecast period.

Snowpack Summary

Due to switching winds, wind slabs can be found mainly on N-NE aspects and S-SW aspects in the alpine on exposed slopes at treeline. Reports indicate the new wind slabs are not bonding well to the southerly scoured, sun crust surfaces. The total settled storm snow is near 60cm and sits over a variety of old surfaces. These include melt-freeze crusts at lower elevations and spotty areas of surface hoar in sheltered treeline areas. Where they exist, they may act as sliding layers. Easy shears persist in the new storm snow down 25-40 cm with sudden planar results. The mid and lower snowpack is well bonded and strong.

Avalanche Problems

Wind Slabs

New snow and moderate SW winds may form new wind slabs Tuesday night though Wednesday on Northerly aspects.

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

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1 - 5

Storm Slabs

The region may receive 15 cm of new snow overnight. This will add to the current storm slab instabilities; especially in areas where they overlie buried crusts, facetted snow, and/or sheltered areas with buried surface hoar.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 5