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Avalanche Forecast

Feb 27th, 2012–Feb 28th, 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
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
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
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Sea To Sky.

Confidence

Good

Weather Forecast

Tuesday: An approaching Pacific frontal system from the North may bring cloudy skies with light snow amounts through the day. Ridgetop winds from the South @45km/hr. Treeline temperatures near -9. Wednesday brings mainly unsettled conditions with lsnow amounts near 10cm. Ridgetop winds moderate from the SW. Thursday: Cloudy, few flurries. Treeline temperatures near -8. Ridgetop winds light-moderate from the NW.

Avalanche Summary

Fairly widespread natural cycle up to size 2.5 occurred through the weekend. Most elevations and aspects seemed to be ripe. Several heli remotes occurred during an operational bombing mission yesterday, up to size 2. These were on NE-SW-W aspects above 2200m. Crown depths 10-25cm, within the recent storm snow. Skier triggered avalanches up to size 2 have also been reported on northerly aspects. I suspect the natural activity will start to taper off, with the exemption of possible solar effect on southerly aspects. I do think avalanche conditions will remain touchy, and susceptible to rider triggers through the forecast period.

Snowpack Summary

The recent total settled storm snow is near 60cm. This storm was initially accompanied by moderate to locally strong south and west winds, creating intense slab production on North through East facing terrain at treeline and in the alpine. Wind slab releases on north facing terrain have been as deep as 100cm. At the end of the storm winds turned northerly, and intense reverse loading occurred on southerly aspects. Reports indicate the new wind slabs are not bonding well to the southerly scoured, sun crust surfaces. All this new snow sits on a variety of old surfaces. These include melt-freeze crusts at lower elevations and spotty areas of surface hoar in sheltered areas. Steep south aspects in the alpine also host a buried sun crust. Easy shears persist in the new storm snow (decomposing fragments down 25cm) and at the deeper interface (down 60cm). Below this, the mid and lower snowpack is well bonded and strong.

Avalanche Problems

Wind Slabs

Recent wind shift (from southwest to north) has exacerbated the wind slab problem.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 5

Storm Slabs

Storm slabs linger as an avalanche problem in areas where they overlie buried crusts, facetted snow, and/or sheltered areas with buried surface hoar.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4