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Avalanche Forecast

Mar 13th, 2013–Mar 14th, 2013
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
4: High
The avalanche danger rating in the alpine will be high
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: South Rockies.

More heavy precipitation in the forecast is keeping avalanche danger high.

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Wednesday night and Thursday: Another wave associated with the frontal system should bring some light precipitation quantities (10 mm until Thursday evening) and with strong W winds easing off a bit Thursday but staying in the moderate to strong speeds.  Freezing levels rising to 2000 m.Friday: Precipitation should start tapering off as the westerly flow weakens. Temperatures and freezing level are expected to remain high. Winds are also looking similar in the moderate to strong from the W. Saturday: Some light precipitation is expected but not as significant as before. Light SW winds and freezing levels staying at a similar height as Friday but starting to drop.

Avalanche Summary

There was a widespread natural avalanche cycle in the Lizard Range region up to size 3 on all aspects and all elevations. Some natural loose and slab avalanche activity was also observed in the South Rockies up to size 2.5 also at all elevations some of which are suspected to have been triggered by cornice fall.

Snowpack Summary

The warm storm has already added a significant load onto the snowpack (around 30 mm of water equivalent in the higher snowfall areas). Another pulse of precipitation will add weight onto the storm slab and the already moist/wet snowpack below the freezing line (around 2000 m.).  In the alpine and at treeline, the new snow sits on a hard wind slabs lee of N, SW and W winds in alpine and treeline features, a well developed surface hoar in shaded areas above 1700 m., a melt-freeze crust below that elevation and a 3 cm sun crust on solar aspects at all elevations. At lower elevations, the wet precipitation will keep soaking up the snowpack possibly weakening it especially where there is a good buried sliding surface like a crust.

Avalanche Problems

Storm Slabs

Warm and wet storm has created and is going to keep developing storm slabs, new wind slabs lee of strong SW winds in the alpine, loose dry avalanches above 2000 m. and possibly wet slab and loose avalanches below that level.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Avoid exposure to overhead avalanche terrain, as large avalanches may reach the end of runout zones.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 6